Category: Inverters

What is a micro-inverter?

What is a micro-inverter?

What is a micro-inverter?

A micro-inverter is device that connects to a single solar panel, converting DC (direct current) from the panel into AC (alternating current), which can power household appliances or be sent into the grid for energy credits. Unlike string inverters, micro-inverters control the output of a single panel. This article outlines the pros and cons of using micro-inverters in your solar power system.

In solar power systems, the inverter is like the brain of the system. It takes the DC (direct current) electricity produced by solar panels and converts it into AC (alternating current), a format that can be used to power your appliances and sent into the utility grid.

Traditional inverters, called string inverters, are designed to manage groups (or series strings) of panels plugged into an input on the inverter. For example, you might wire 24 solar panels into an SMA Sunny Boy inverter in two strings.

But micro-inverters are different. In a micro-inverter system, each micro-inverter is paired to its own panel. So in the same 24-panel system, you would have 24 micro-inverters installed—one on each panel.

On a per-panel basis, micro-inverters like the Enphase IQ7+ cost a bit more than basic string inverters. But micro-inverters come with features that can optimize the overall output of your system, providing a boost in efficiency that offsets the higher up-front cost.

In this article, we’ll explain what a micro-inverter is, then outline the pros and cons of micro-inverters to help you decide whether you should consider them for your solar project.

What is a micro-inverter?

In simple terms, a micro-inverter is an inverter that controls the output of a single solar panel. Each micro-inverter that is paired with a solar panel essentially creates a self-contained solar energy system. 

Mount it to the back of the panel, plug it in, and you’ve got a system that produces energy, regardless of whether you’ve installed 1 panel or 100.

Advantages of Micro-Inverters

Due to the way they’re configured, micro-inverters have a few key advantages compared to string inverters that justify the higher price tag.

Power Optimization

In order to explain the problem micro-inverters are built to solve, we first need a bit of background context about how string inverters work.

With a traditional string inverter, groups of panels are wired in series. If you have 8 panels in a string, all 8 panels are part of the same circuit, which means they are subject to the same electrical characteristics. 

If the output of a single panel drops, the whole circuit drops to match the reduced output of the under-performing panel. You might have a string of 350W panels, but if one panel falls to 300W output, every panel in the string is restricted to that 300W mark.

Using string inverters, a drop in production from one panel drags down the output of the rest of the array.

With micro-inverters, each panel is isolated from the rest of the array. One shaded panel may drop to 300W, but the rest of the panels remain unaffected and continue to produce at its 350W capacity.

With micro-inverters, a drop in production from one panel doesn't affect the rest of the array.

The net result is that micro-inverters allow you to produce more power out of the same panels. In areas where trees or other obstructions will cast shade on your panels, micro-inverters are well worth the investment. 

Isolated Equipment Failure

Similar to the above point, if a piece of equipment fails completely, the rest of the array won’t be affected. 

Let’s say a panel malfunctions due to faulty wiring and stops producing power. With micro-inverters, that panel is isolated, so the rest of the array keeps producing power. The other panels will continue to work, so you are not stuck without a working system while you file a warranty claim and get it replaced.

With a traditional string inverter like the SMA Sunny Boy, the entire string could be affected to the point where the inverter wouldn’t produce power. You could potentially be left in the dark until you replace the faulty panel.

Ease of Installation

Micro-inverters use standard AC wiring, similar to what is used throughout your house. They are also plug-and-play, with each unit plugging into the next. 

As a result, micro-inverters are extremely easy to install and connect because they use standard AC wiring and it only takes a few seconds to plug in each unit. 

Expandable Design

What if you want to start small and expand your system later? Maybe you don’t have the budget to offset 100% of your energy usage, but you want to get into a smaller system so you can start reaping the benefits of solar. Or maybe you want a self-contained array to power your shed as a “test run” to see if it makes sense to power the rest of your home with solar.

Due to their 1-to-1 nature, systems with micro-inverters can essentially be as small or as large as you want them. If you want, you can start with a single panel+micro-inverter pairing. Adding more panels later isn’t a problem, because none of the existing equipment needs to be moved or re-wired to facilitate the addition.

The same isn’t possible with string inverters, which have minimum string size requirements because the panels need to supply enough voltage to the inverter to power it on. In the linked example, the system is limited to 7-10 panels per string. Outside that range, the inverter may not function properly.

Which means that if you have any future plans for expansion, micro-inverters are the way to go. You can start with a small system now and add on to it later without hassle.

Flexible Array Layout

Panels produce the most energy when they face South (directly at the sun), while East- and West-facing panels will lag behind. 

With string inverters, you typically want all panels in a string to face the same direction. If you mix South- and East-facing panels on the same string, the panels facing East will drag the rest of the string down.

Micro-inverters give you more flexibility with the layout of your array. Depending on your roof configuration, you may need to design a system to distribute panels across multiple sections of your roof. With micro-inverters, the output of each panel is isolated, so you can distribute them however you want without sacrificing output.

Suniva 340 watt solar panel array
These panels have been split across different sections of the roof to take advantage of the limited space available.

Meets Module-Level Rapid Shutdown Requirements

Lastly, the IQ7+ is designed to meet Rapid Shutdown requirements outlined in the latest version of the National Electric Code without the need for any additional equipment.

In short, solar systems need to be able to “de-energize” quickly in case of emergency. If a house were to catch fire, the firefighters may need to climb on the roof and cut a hole to ventilate the smoke. In doing so, they could cut through the solar wiring, which is often routed into the attic to run alongside the roof rafters.

As a safety measure, roof-mounted systems need a way to quickly release the live current running through the wires, to prevent the risk of shock for first responders.

The IQ7+ meets Rapid Shutdown requirements by default. For the SMA Sunny Boy, you’d have to add something like the FireRaptor Rapid Shutdown Unit at an additional cost to meet the regulations.

It’s worth noting that this section only applies to roof-mount systems. Ground-mounted systems won’t interfere with first responders who need to work on your roof, so they’re exempt from the Rapid Shutdown requirements.

Disadvantages of Micro-Inverters

More Expensive Up Front

Of course, the flexibility and added features of micro-inverters make them more expensive than traditional string inverters. A system with Enphase IQ7+s will cost around 15-20% more per panel than an equivalent SMA Sunny Boy system.

That higher initial investment is well worth it if you live in harsh climates, where inclement weather can put a damper on production. It also makes sense if your site is shaded by trees or other obstructions. In these cases, micro-inverters will salvage production that would have otherwise been lost, easily offsetting their higher price tag.

But if your system will be built in a location with full sun exposure, a standard string inverter is a perfectly good option. If shading isn’t a concern, the SMA Sunny Boy will perform comparably to a micro-inverter system at a much lower price point.

Higher Odds of Equipment Failure

In the “pros” section, we mentioned that adding a micro-inverter to each panel can isolate equipment failures. Even if a panel malfunctions, the output from the rest of the array won’t be affected.

The flip side is that micro-inverters introduce more potential failure points. If your system has 24 micro-inverters, the odds that a piece of equipment will malfunction go up compared to a system with a single string inverter.

Another point is that micro-inverters may be more challenging to replace for rooftop installations. Since they are attached to your panels, it may be a pain to climb on the roof and replace one in the middle of an array. By comparison, string inverters are always installed at ground level, making them much easier to replace if necessary.

When Are Micro-Inverters the Right Choice?

Micro-inverters are the best option if you need to build your system under less-than-ideal circumstances. If your panels will be shaded, or part of the array will face East/West due to the configuration of your roof, micro-inverters ensure your system produces as much power as possible.

If you have plenty of space to build your array in full exposure to sunlight, a traditional string inverter may be the better bet, as it can perform the same job for 15-20% less money up front.

For more info, check out our reviews of a few inverters we carry:

You can also grab a free copy of our Solar Inverter Guide by clicking below.

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SolarEdge HD-Wave Review: Pros & Cons, Pricing, Specs (2019 Edition)

SolarEdge HD-Wave Review: Pros & Cons, Pricing, Specs (2019 Edition)

The SolarEdge HD-Wave is our most popular inverter. While it’s not the least expensive option on the market (a title held by the SMA Sunny Boy), the HD-Wave’s power optimizers put in a ton of legwork to ensure your system always produces at maximum efficiency.

Most people run into some hurdles and challenges during the system design process. Maybe their roof design prevents them from facing every panel in the same direction. Or they might realize that trees, chimneys or other obstructions will cast shade on the area where they plan to build their array.

In these cases, a classic string inverter won’t cut it, because production drop from a single panel translates to the entire string—meaning shade on a single panel can tank your system’s output. Power optimizers like the ones included with the HD-Wave become a necessity to isolate the affected panel and maximize the production from the rest of the panels in the string.

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This HD-Wave review will cover basic specs, pricing, and pros and cons of the product, as well as explain when you might choose the HD-Wave over other inverters to power your solar electric system.

SolarEdge HD-Wave Pricing

SolarEdge offers a range of HD-Wave models from 3.8 kW to 11.4 kW for residential grid-tie systems. Please note that the prices published here are current as of 3/14/19, but are subject to change in the future. Click the product links to view current pricing in our shop.

ModelPriceCost Per Watt
HD-Wave 3.8 kW$1,12530 cents/watt
HD-Wave 5 kW$1,39928 cents/watt
HD-Wave 6 kW$1,42524 cents/watt
HD-Wave 7.6 kW$1,57521 cents/watt
HD-Wave 10 kW$2,17521 cents/watt
HD-Wave 11.4 kW$2,37521 cents/watt

HD-Wave SE7600 Specs

  • Model: SolarEdge HD-Wave 7.6 kW
  • Wattage: 7600 watts
  • Peak Efficiency: 99.2%
  • Warranty: 12 years
  • Input voltage: 400V DC
  • Output voltage: 240V AC
  • String Inputs: 2

Ideal Application

The HD-Wave is one of three inverters we recommend with our grid-tie systems, alongside the SMA Sunny Boy and Enphase IQ7+ micro-inverters.

Both of the other options have specific use cases:

  • If your system won’t suffer shading or other production drop issues, the Sunny Boy is the most cost-effective option. Read our Sunny Boy review.
  • If you want to start small and expand your system later, or need to work around an unusual array layout with panels facing different directions, go for the IQ7+ micro-inverters. Read our IQ7+ review.

For all other systems, we turn toward the HD-Wave as our go-to recommendation. The power optimizers mitigate shade and other production drop issues better than the Sunny Boy, and it’s more cost-effective than buying IQ7+ micro-inverters for every panel (especially on a large scale).

The HD-Wave is our “one-size-fits-all” inverter that strikes a balance between budget and efficiency. The optimizers ensure you are getting as much production as possible from your panels, making it versatile enough to work with almost any system. And for systems that are 6-8 panels or larger, the HD-Wave costs less than an IQ7+ micro-inverter system.

Pros of the HD-Wave

Power Optimization

The main selling point for the HD-Wave is that the power optimizers allow the inverter to monitor and optimize the output of each panel independently.

Classic string inverters like the Sunny Boy have a major limitation: if the output of one panel in a string drops, every panel in the string drops to match the reduced output.

You may own a string of ten 330W panels, but if shade falls on one panel and drops the output to 250W, all ten panels in the string will produce 250W apiece. An issue with a single panel causes a 25% production drop across the array.

The HD-Wave’s power optimizers solve this problem.

By attaching an optimizer to each panel, your inverter will monitor each panel separately and make any adjustments necessary to keep the system producing at an optimal level.

Panels that underperform (due to factors like shade, poor orientation, or equipment malfunction) are isolated thanks to the optimizers. Reduced output from one panel doesn’t translate to the rest of the string.

In addition, the HD-Wave can call on the optimizers to boost the voltage coming from other panels to compensate for the underperforming panel. This keeps the inverter in a voltage range that allows it to operate at peak efficiency.

Safety Measures

Optimizers make the HD-Wave compliant with the rapid shutdown requirements outlined in the latest National Electric Code (NEC 2017 690.12). This is a safety measure that automatically shuts down your array in the event of a power outage.

The code is in place to ensure the safety of emergency responders—for example, firefighters would not have to worry about shutting down the array before putting out a fire on the property.

An HD-Wave with the rapid shutdown safety feature.

The HD-Wave has some other great safety features as well. The optimizers prevent your panels from producing more than 1 volt of power until everything is hooked into the inverter and the system has been tested and commissioned.

Essentially, the inverter will verify it has been wired correctly before it starts to produce power. There’s no shock risk because the wires aren’t electrified until the system runs checks to ensure it is set up properly.

This failsafe makes installation way less scary and more approachable for someone looking to DIY install.

Monitoring

SolarEdge offers a full-featured monitoring portal to help you view and manage the production from your system, as well as each individual panel.

The monitoring provides fault detection and active alerts about the health of your system. It also provides interactive charts and reports to help you visualize production and energy consumption over the life of the system.

It’s the most robust monitoring portal we’ve found, and it’s completely free for the first 25 years of system ownership (the standard warrantied life of a solar panel).

Temperature Rating

SolarEdge is in the process of rolling out product updates to the entire HD-Wave line. The newest models benefit from a wider temperature range.

Previously, the standard SolarEdge inverters were rated to -13°F / -25°C. The new models are rated for -40°F / -40°C. The increased cold tolerance will be especially useful for installations in the midwest and north-eastern United States, where temperatures can fall well below zero.

If you live in a particularly harsh, cold climate, look for the new SetApp HD-Wave inverters to help keep your system operational during winter. (We should point out that there have been mixed reactions to the new design—we will go over those changes in the Cons section.)

Access to Support

SolarEdge has a great support network available to the end user. Their products are well-documented and if you run into a problem, you’ll likely find a technical article in SolarEdge’s resource center to help you solve it.

They also have a community-driven knowledge base and even offer live support through online chat, a rarity in the industry. It’s clear SolarEdge puts a priority on their customers being well-informed and well-supported.

Cons of the HD-Wave

Won’t Work Without Optimizers

The HD-Wave was built from the ground up to monitor and control the production from each individual panel in your system.

As a result, the power optimizers are mandatory—your HD-Wave simply won’t work without them (unlike the SMA Sunny Boy, which works with or without optimizers).

Power optimizers are a mandatory part of the HD-Wave package.

This can be a good thing or a bad thing depending on the nature of your solar project.

If you can build your system in full sunlight and face the panels in the same direction, you won’t run into many production drop issues. That would make the HD-Wave’s mandatory power optimizers an unnecessary expense. In these cases, you’d be better off with the Sunny Boy, which can do the same job for 15-25% less money.

However, if you think you’ll encounter shading issues, the HD-Wave is the better choice. It is more efficient, has smarter power optimization tools and more detailed reports in its monitoring portal. If you know you’ll need production drop mitigation from the start, the purpose-built HD-Wave is better equipped for the job.

Frequent Design Changes

We’ve sold SolarEdge products for a while, and one thing we’ve noticed is that they make frequent updates to their product design. It seems like the form factor changes every generation, with ports being moved and internal components reorganized.

That makes their products harder to support because there’s not a lot of consistency between models. When troubleshooting, much of the advice you find becomes obsolete as the product design changes with each new product update.

Speaking of this…

Will Soon Require Smartphone to Commission & Monitor

SolarEdge has announced a major update to the HD-Wave which entirely removes the display screen from the inverter unit.

Functions that could previously be performed on the built-in display screen, like initial system setup and status checks, will now be handled through a smartphone app called SetApp instead.

New HD-Wave models will require a smartphone to commission.

The 10 kW HD-Wave has already been updated to the SetApp model. SolarEdge is in the process of upgrading every model with these features, so we expect this major change to roll out to the rest of the HD-Wave product line in short order.

We have mixed feelings about this change. The design has been streamlined, but it comes at the expense of some basic functionality. The buttons and display were helpful for quick tasks like checking production and system health at a glance.

But the real downside is that you must commission your system through the SetApp smartphone app, which means that if you don’t have a smartphone, you won’t be able to turn your system on.

Repeated for emphasis: if you do not have a smartphone you cannot install a new SetApp HD-Wave inverter.

Moving basic functionality to an app makes the HD-Wave less accessible for people who don’t own smartphones, but we can see the decision has some inherent advantages as well.

The main benefit is ease of installation. SetApp will apply firmware updates, pair optimizers to panels, and commission the system automatically. It’s a much easier interface than performing setup manually on a tiny screen.

The end result is that system setup is more streamlined for most people, but will cause headaches for those who don’t own a smartphone or have access to Wi-Fi.

SolarEdge HD-Wave Review: The Verdict

The HD-Wave inverter is our best-selling inverter for a reason. Our other recommended options only make sense in specific scenarios:

  • The Sunny Boy is a better value if you can build in full sunlight and can face your panel strings the same direction, bypassing the need for need power optimizers.
  • IQ7+ micro-inverters are more flexible if you need something that is easy to install and expand, with no restrictions on system size or array layout.

For anything else, we recommend the HD-Wave as an all-purpose inverter that’s fit to handle just about any grid-tie solar project. Even if you can’t face your panels directly South, or the array will be partially shaded, the power optimizers will keep the system running as close to its rated output as possible.

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SMA Sunny Boy Review: Pricing, Specs, Pros and Cons (2019 Edition)

SMA Sunny Boy Review: Pricing, Specs, Pros and Cons (2019 Edition)

SMA Sunny Boy Review: Quick Summary

The SMA Sunny Boy costs less than other grid-tie inverters, but it only works if you build your system in full sunlight and face all your panels in the same direction.

The Sunny Boy is our preferred choice if you don’t need panel-level power optimization. But if you face issues with panel layout or shading, you’ll be better served by the SolarEdge HD-Wave or Enphase micro-inverters.

SMA has long been regarded as one of the most reliable string inverter manufacturers in the solar industry. In this article, we’ll review the SMA Sunny Boy, our pick for best inverter for “standard” grid-tied solar systems.

The Sunny Boy shines in systems that won’t be affected by shading, panel orientation, or other concerns that would impact production from your panels.

It’s not the most versatile, high-tech inverter around. But if you’re building a typical fixed-mount system that will receive full sunlight year-round, the Sunny Boy gives you more bang for your buck than any other grid-tied inverter on the market.

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SMA Sunny Boy Pricing

SMA offers a range of Sunny Boy models from 3 kW to 7.7 kW for residential grid-tie systems. Please note that the prices published here are current as of 3/11/19, but are subject to change in the future. Click the product links to view current pricing in our shop.

ModelPriceCost Per Watt
Sunny Boy 3.0kW$1,22541 cents/watt
Sunny Boy 3.8kW$1,25032 cents/watt
Sunny Boy 5.0kW$1,32526 cents/watt
Sunny Boy 6.0kW$1,42524 cents/watt
Sunny Boy 7.0kW$1,67524 cents/watt
Sunny Boy 7.7kW$1,72522 cents/watt

SMA Sunny Boy 7.7 kW Specs

Here’s a quick look at the specs for our most popular Sunny Boy model, the 7.7 kW configuration. It’s worth noting that the 3.0 and 3.8 kW models have 2 string inputs (instead of 3), but other specs like efficiency, warranty and voltages are the same for all the residential models listed in the table above.

  • Model: Sunny Boy 7.7 kW
  • Wattage: 7700 watts
  • Peak Efficiency: 97.5%
  • Warranty: 10 years
  • Input voltage: 600V DC
  • Output voltage: 240V AC
  • String Inputs: 3

Ideal Application For The SMA Sunny Boy

It’s important to understand the limitations of string inverters to help decide whether they are the right choice for your project.

A panel string is a group of panels that is wired into a single input on the inverter. Because the panels are wired in series, the production of every panel in the string is linked together.

If one panel suffers a drop in production, every panel in the string drops to match the output of the weakest panel.

Panel string diagram
Panel strings are wired in series. Production drop from one panel translates across the entire string.

You may own a string of 330W panels, but if a single panel in the string falls to 250W production, every panel in that string is going to produce 250W of power. That’s an 800W production loss over a 10-panel string—nearly a 25% loss in output.

For this reason, the Sunny Boy only makes sense when you can build your panels in a location that is fully exposed to sunlight year-round.

If trees, chimneys or other obstructions throw shade on a panel, it will cripple the production of a string, which affects your entire system.

It’s also not ideal if your panels face different directions—if you need to spread them across an unusually-shaped roof, for example. Panels work best when they face directly into the sun (ideally, you want to point them toward the Equator, which means a South-facing array is ideal for systems built in the US).

If some panels in a string face South and some panels face East, the East-facing panels will produce less power because they don’t point directly into the sun. The entire string will drop to match the output of the East-facing panels, sacrificing the extra output from those that face South.

Different strings can have different orientations, but all panels in a string should face the same direction.

To mitigate these issues, you would be better served by an inverter system with panel-level optimization like the SolarEdge HD-Wave or Enphase IQ7+ micro-inverters.

However, if you don’t need to worry about shade or panel orientation, Sunny Boy systems are extremely reliable and efficient at a price that is 15-25% less than alternative options. It’s the best value you can find on an inverter, assuming you meet these ideal build requirements.

Compare your options with our video review of the best grid-tie inverters on the market:

Pros of the SMA Sunny Boy

Best Value Inverter on the Market (In Ideal Conditions)

The Sunny Boy is the most cost-effective grid-tied inverter you can buy, provided your system meets a few criteria:

  • Built in full sunlight (not blocked by trees, chimneys or other obstructions)
  • Panels face the same direction
  • Large enough to meet minimum string sizing requirements (at least 4-6 panels depending on the panel and inverter models you choose)

Let’s compare two systems that would produce 906 kWh per month, enough to offset the national average energy usage for American households. (Prices are current as of 3/7/19.)

The systems are identical aside from the inverter equipment, and the Sunny Boy system costs nearly $1,600 less than the HD-Wave. You can save quite a bit of money if your system is built in full sunlight and you don’t need the power optimizers featured in the HD-Wave system.

Secure Power Supply

A feature unique to SMA inverters is the Secure Power Supply (SPS). The SPS provides a source of backup power in case of emergencies.

If your power goes out, you can plug into the SPS, a 2000-watt power source that draws backup power from your panels even if the grid is down. This is a nice failsafe to power critical appliances during an outage.

One caveat is that your panels must be exposed to sunlight and producing power for this to work, since the SPS draws electricity in real-time from the panels to make this feature work. At night or during heavy storms, the SPS is not a reliable substitute for a fully-equipped grid-tie system with energy storage.

Optimizers Are Optional

The SolarEdge HD-Wave comes with mandatory power optimizers—the system won’t work without them. With the Sunny Boy, the optimizers are an optional add-on.

This gives you the flexibility to start with the base Sunny Boy package, then retrofit optimizers on to the panels if you think they’re necessary.

For example, your system might be fully exposed to sunlight in the summer, but then you find that your house casts a longer shadow in the winter and covers part of your array. You can go back and add optimizers to the shaded panels to bring their production back up to par.

There is a trade-off, though. When you add optimizers, the Sunny Boy loses its Secure Power Supply functionality. This is a design oversight that we hope to see corrected in future models.

Nevertheless, it’s nice to have the flexibility to retrofit your panels with power optimizers should the need arise.

Great Customer Support

SMA has some of the best customer support in the industry. Their customer-facing tech team is knowledgeable and has great response time via phone and email. They also produce detailed product documentation to help people install, program and troubleshoot their equipment.

As a distributor, we’ve found them to be fair and responsive working with us to troubleshoot faulty equipment and process return claims.

In an ideal world, great support should come standard, but unfortunately that’s not always the case. Some solar manufacturers don’t even offer direct-to-consumer support, instead forcing the distributor to mediate technical issues and return claims.

Not SMA, though: their support team is one of the most accessible and competent in the business.

Cons of the SMA Sunny Boy

System Design Limitations

As mentioned above, the Sunny Boy works best if all your panel strings face the same direction and you can build your array in full sunlight.

If you don’t meet these requirements, production will drop fairly dramatically, and the Sunny Boy is no longer the most cost-effective option.

While the Sunny Boy shines in its wheelhouse, it’s not the most versatile inverter on the market. The SolarEdge HD-Wave is more fully-featured and tends to be the better pick when you need panel-level power optimization.

Rapid Shutdown Limitations

The newest electrical codes (NEC 2017) require rapid shutdown for PV systems installed on buildings.

For Sunny Boy systems, that requires adding optimizers, which means you lose the SPS feature—and the cost advantage over other inverters. A Sunny Boy with optimizers costs about the same as a SolarEdge HD-Wave system.

If you know you need optimizer technology from the start, you’re better off with a SolarEdge or Enphase system, which are built from the ground up for that purpose. SMA’s optimizers are an add-on to the Sunny Boy, which wasn’t originally designed with power optimization in mind.

Rapid shutdown requirements only apply in certain areas, and only when the system is installed on a building. Roof-mount systems often require optimizers to comply, but in many cases ground-mount systems are exempt.

Harder to Install

The Sunny Boy is larger and heavier than other inverters, making them a bit more challenging to install, especially for a DIYer working alone.

Larger Sunny Boy models weigh 57 pounds. They can be pretty hard to manage when you’re trying to lift and mount the inverter on your wall.

(Believe it or not, older models were heavier because they ran on transformers, while the latest Sunny Boy line is transformerless. Still, the Sunny Boy 7700 weighs more than twice as much as the 26.2-pound HD-Wave 7600).

It’s the largest and heaviest inverter we stock, and can be a bit challenging to mount if you are installing your own system without any outside help.

Short Warranty

The standard 10-year warranty is shorter than SolarEdge’s 12-year warranty on the HD-Wave, and much shorter than the 25-year warranty on Enphase IQ7+ micro-inverters.

You should expect to replace your Sunny Boy at least once, and possibly twice, over the life of your system.

SMA does offer an extended warranty plan that allows you to stretch the product warranty up to 20 years. Whether you buy the extended warranty up front or replace the inverter out of pocket later, you’ll incur some additional costs for a replacement at some point. Those costs should be factored into the lifetime ownership cost for your system.

SMA Sunny Boy: The Verdict

Our evaluation of the Sunny Boy is pretty simple. If you can build in full sunlight and don’t have any complicated layout requirements, the Sunny Boy is the best all-around value you can find.

If you need more advanced power optimization for individual panels, are working with an unusual array layout, or simply want a system that is easier to install, the SolarEdge HD-Wave or Enphase IQ7+ micro-inverters are going to be better options.

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Enphase IQ7+ Review: Pricing, Specs, Pros and Cons (2019 Edition)

Enphase IQ7+ Review: Pricing, Specs, Pros and Cons (2019 Edition)

The latest addition to Enphase’s line of micro-inverters is here: the Enphase IQ7+. The IQ7+ has been upgraded to a higher 290W output (up from 280W), which allows you to pair it with slightly larger panels than the previous model allowed.

The Enphase IQ line remains our go-to micro-inverter pick for grid-tie systems thanks to their ease of installation, shade tolerance, and flexible array design. The latest generation features an increase in capacity to the IQ7+ model and introduces the new IQ7X, which is compatible with 96-cell modules.

Keep reading for our complete Enphase IQ7+ review. We’ll go over pricing, specs, ideal application, and pros and cons of the IQ7+.

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IQ7+ Price and Specs

  • Price: $142 apiece (plus $16 apiece for mandatory Q Cable connectors, totaling $158 per unit)
  • Wattage: 290 watts
  • Peak Efficiency: 97.6%
  • Warranty: 25 years
  • Input voltage: 16-60V DC
  • Output voltage: 240V AC
  • Works with: 60-cell and 72-cell modules

Price

Please note that prices are current as of 3/5/19. Prices are subject to change; visit the Enphase IQ7+ listing in our shop for current pricing.

The IQ7+ package costs $158 per panel, which is great if you want to start small and ease your way into solar. Once you grow beyond about 10 panels, the scales start to tip in favor of SolarEdge HD-Wave systems as the more cost-effective option.

The price difference is minor for a system this size—$1.45/watt for the IQ7+ system vs. $1.42/watt for the HD-Wave system—and the ease of installation for the IQ7+s often justifies the higher price tag.

However, as systems grow in size, the price difference gets more pronounced. You don’t see too many larger systems (10kW+) built on micro-inverters because they are less cost-effective at a larger scale.

Learn more about which inverter is right for your system:

Power Output

The IQ7+ is sized to output 290 watts of power. Realistically, you can (and should) pair them with slightly larger panels, up to the 325-335W range. This is to account for natural efficiency losses in the system. As a rule of thumb, you’ll lose about 10% of the panel wattage due to inefficiencies caused by factors like temperature.

You also want to oversize panels to stay closer to 290 watts of output during sub-optimal production conditions. This could occur to shading or other obstructions, but it also keeps you closer to max wattage during off-peak times of day (when the sun isn’t directly overhead).

However, you don’t want to go too large with your panels, because you’ll waste any overhead production during peak periods. The Enphase spec sheet suggests the IQ7+ is compatible with panels up to 440W, but that’s overkill given any power generated above the 290W cap is wasted. We’ve found that 335W is a good upper limit for the rated output of the IQ7+.

Why use micro-inverters?

To answer this question, let’s look at the limitations of string inverters.

String inverters set restrictions on your panel string size—the number of panels that can be wired together and plugged into a single inverter input.

Panel strings typically contain 6-10 panels, which helps the inverter operate at peak efficiency. Too many panels (or too few) and your inverter won’t work properly.

The other major limitation is that panels in a string are linked together. When one panel in the string suffers reduced output (due to shading or technical malfunction), every panel in the string drops to match that reduced output.

You may own a string of 330W panels, but if a single panel in the string falls to 250W production, every panel in that string is going to produce 250W of power. That’s an 800W production loss over a 10-panel string.

Systems with power optimizers (like the SolarEdge HD-Wave) mitigate this issue somewhat by enabling each panel to produce independently. But the HD-Wave is still restricted by minimum string size requirements, and shading across the string can still cause it to fall below the minimum input voltage.

Micro-inverters are designed to work around these limitations.

Pairing a micro-inverter with a panel essentially creates a self-contained, single-panel solar system. It doesn’t matter how many panels you buy—each panel in the system functions independently.

Start with a single panel hooked into an IQ7+ if you want. This allows you to start small and offset a portion of your utility bill as soon as possible, then expand the system as budget allows.

Micro-inverters are also the most shade-tolerant option. Shade on one panel will never impact the rest of your system. You don’t have to worry about a group of panels meeting a minimum string voltage, because each one functions as a self-contained system.

Finally, micro-inverters are easier to install. Simply chain each Q cable from one unit to the next, with the final wire terminating in a junction box. They’re easier to install than string inverters because micro-inverters utilize common household AC wiring, which is readily available and simple to install.

Read more: Micro-Inverters vs. String Inverters

Pros of the Enphase IQ7+

No String Sizing Requirements

With micro-inverters, you don’t have to worry about how many panels you group together. This means they are less impacted by shading. They are also easier to expand. Start with one panel and one IQ7+ if you want. This allows you to offset a portion of your utility bill as soon as possible, then expand the system as budget allows.

Easy Installation

One thing we really like about the IQ7+ is how extremely easy they are to install. There’s an input for your panels and an output to chain the Q cables from unit to unit, with the last one plugging into your junction box.

From the junction box to your breaker panel, you’ll install standard household AC wiring, which is much easier and cheaper to install compared to the DC wiring used with string inverters and optimizers. This can save you a lot of time, money and hassle messing around in your attic.

It’s also dead simple to tell at a glance whether your system is functioning properly, thanks to a light on the unit that changes color based on its status:

  • Green: Everything is working.
  • Yellow: Micro-inverter works, but is not communicating with IQ Envoy monitoring system.
  • Red: Micro-inverter is not working and panel is not producing power.

The simplicity of the IQ7+ streamlines the wiring process, making it ideal for DIY installs.

Compatible with 60-cell and 72-cell panels

Standard solar panels contain either 60 or 72 cells. Since there’s no difference in performance or cost-per-watt between the two options, it’s nice to have access to both when designing your system. The IQ7+ is configured to work with both options.

The standard IQ7 only works with 60-cell panels due to its lower voltage and wattage. The IQ7X pairs with 96-cell panels on the market from the likes of Panasonic.

With the IQ7+, you can choose to work with 72-cell panels if you want. For example, this 72-cell 335W Astronergy panel and this 60-cell 310W Mission Solar panel are both compatible with the IQ7+, but the 72-cell option helps you squeeze a bit more wattage out of every panel.

Since 72-cell panels are physically larger, you’ll be installing fewer panels and micro-inverters. That means less racking material, fewer holes in the roof, and fewer connections to hook up, which makes installation quicker and easier on the whole.

25-year warranty

This is a big one. The 25-year warranty on the IQ7+ far surpasses the SMA Sunny Boy (10 years) or SolarEdge HD-Wave (12 years). That’s important because it matches the 25-year warranty that comes standard on Tier 1 solar panels in today’s market.

With string inverters, you’ll need to budget for at least one inverter replacement over the life of the system. You’ll have to choose whether to pay more up front for an extended warranty, or cover the replacement out of pocket when the time comes.

The IQ7+ comes with a standard 25-year warranty. If one of your micro-inverters ever malfunctions at any point in your system’s lifetime, you’re covered for a free replacement. No maintenance fees or hidden ownership costs to worry about.

Compliant With Rapid Shutdown Codes And Smart Inverter Regulations

In the event of an emergency at your home, first responders must be able to quickly and safely turn off your system to negate the risk of electrical shock from live DC circuits coming from the array. The IQ7+ is fully compliant with the most recent national rapid disconnect codes (NEC 2017 690.12).

It also meets the definition of a “smart inverter” under California’s Rule 21. Smart inverters interface with the utility grid to control when and how your system feeds electricity to the grid. This helps the utility smooth the demand curve and deliver more reliable power during peak usage periods.

The IQ7+ is code-compliant and cleared for installation in all 50 states (unlike the Magnum MicroGT, which cannot be used in California or Hawaii because it does not meet local code requirements).

Cons of the IQ7+

Monitoring Not Included

While we like the IQ7+’s simpler design and ease of installation compared to its predecessors, we’d like to see the monitoring system become a streamlined part of the package.

Right now, you have to buy the Enphase IQ Envoy to be able to monitor your system’s output. The IQ Envoy is a separate unit that requires extra work during installation and commissioning, which only adds more labor to the installation process.

What’s more, the SMA Sunny Boy and SolarEdge HD-Wave come with monitoring platforms built into the inverter at no additional charge. In that context, it’s hard to swallow the idea of paying an extra $500 to add functionality that comes standard with other systems.

More Parts = More Failure Points

The more parts there are in your system, the greater the chances one of them will fail. If you have 20 micro-inverters doing the job of one string inverter, it’s 20x more likely something in your system malfunctions and needs to be replaced.

Even though the IQ7+ is warrantied for 25 years, it still takes time and energy to make a claim and replace it if it fails. Most people just want their system to work without ever thinking about it.

Distributed micro-inverter systems introduce more potential failure points and a higher likelihood of maintenance somewhere down the line. It’s especially important to keep this in mind for roof-mounted systems, which are more difficult (and expensive) to access for repairs.

But the distributed nature of micro-inverters is a double-edged sword. If a string inverter fails, the entire system stops producing. A failed micro-inverter only takes a single panel out of commission.

So while micro-inverters make replacements more likely, they also isolate failure, allowing the majority of your panels to continue producing energy while you replace the defective unit.

Higher Cost Per Watt

Of all the inverter configurations, micro-inverters are the most expensive from a cost-per-watt perspective. As of the time this article was published (3/4/19), here’s how much it would cost to route 20 Mission Solar 310W panels into three different inverter setups:

For full-scale systems, string inverters are more cost-effective option. If you can build in full sunlight, the Sunny Boy costs about 20% less than a micro-inverter system.

Even the HD-Wave, with built-in monitoring and individual optimizers that give you panel-level control, costs less than an IQ7+ setup.

Enphase IQ7+: The Verdict

We recommend the IQ7+ in the following scenarios:

  • You want to start small and expand later
  • You want a system that is easier to install
  • You need a system that is highly shade-tolerant

For a more cost-effective option, especially for larger scale systems, you would be better served with the SMA Sunny Boy or the SolarEdge HD-Wave.

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String Inverters vs. Micro-Inverters vs. Optimizers: Comparing Types of Inverters

String Inverters vs. Micro-Inverters vs. Optimizers: Comparing Types of Inverters

What is an inverter?

A solar inverter converts DC (direct current) into AC (alternating current). Solar panels generate direct current from the sun, but most home appliances run on alternating current. The inverter’s role in your system is to convert DC to AC so that the energy generated by your panels can be used to power your appliances.

This article will break down the three main types of inverters used for solar: string inverters vs. micro-inverters vs. optimizers. Our goal is to provide an entry-level primer that compares pricing, pros and cons, and ideal applications for each type of solar inverter.

String Inverters

What is a string inverter?

SMA Sunny Boy String Inverters, which control the array from a centralized location.

A string inverter is a central inverter with inputs for ‘strings’ of panels to be run into a single unit. Panels are wired together in series, and the end of the chain plugs into the inverter.

String inverters can feature multiple inputs. For example, you might have 3 strings of 8 panels each plugged into the three inputs on an SMA Sunny Boy 7700W string inverter. That would allow you to build a 24-panel system on a single inverter unit.

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Pros and Cons of String Inverters

String inverters are the most cost-effective option available, assuming you meet certain conditions to allow them to work optimally.

You’ve probably heard the saying “a chain is only as strong as its weakest link.” That principle applies to panel strings. When one panel in the string suffers reduced output, every panel in the string drops to that reduced output.

You may have 330W panels, but if a single panel in the string falls to 250W production, every panel in that string is going to produce 250W of power.

Some factors that can cause this drop in production:

Shade. Your panel will produce less energy when it’s shaded, and shading on one panel will impact the entire string.

Panel Facing. Panels produce the most energy when they face directly at the sun. In the US, panels should face South for optimal production. If you split a string of panels on your roof so that half face South and half face East, the South-facing panels will drop to the lower output of the panels that face to the East.

Equipment Malfunction. If one of your panels stops working, your entire string stops working until you repair or replace the defective panel.

For these reasons, we only recommend using string inverters if your system will receive full sunlight year-round and all panels will face the same direction. This tends to work best when you have lots of space on your property and can build a fixed ground mount clear of any obstacles.

Assuming you meet these conditions, string inverters are a fantastic option to help you save some money on your solar project.

What’s the Best String Inverter on the Market?

We like the SMA Sunny Boy line. There are a number of sizes available for residential projects:

One nice feature unique to the Sunny Boy is the Secure Power Supply (SPS), a plug which can output 2000W of emergency power in case of grid outages. The SPS functionality is limited to times when the sun is still shining (as it still draws power from your panels, merely bypassing the grid interconnection). But it’s still a nice backup plan in a pinch.

The SMA can also be retrofitted with optimizers to mitigate production drop (more on this in the next section). However, adding optimizers comes with the trade-off of losing the SPS functionality.

Read more about the Sunny Boy in our review of the best grid-tied solar inverters on the market in 2019.

String Inverters With Power Optimizers

What is a power optimizer?

SolarEdge HD-Wave optimizers on the back of an array of solar panels.

Optimizers can be attached to your solar panels, which enables you to control each panel’s output independently from the rest of the string. This solves the limitations of string inverters. If a single panel under-produces due to shade or malfunction, optimizers ensure the other panels in the string are not affected.

Pros and Cons of String Inverters With Power Optimizers

Adding optimizers gives you much more flexibility with your system design. You can build your array in a partially shaded area or split strings across the usable space on your roof. Optimizers ensure you get the most production out of each panel in your system.

Of course, the tradeoff is the additional functionality comes at a higher cost. A SolarEdge HD-Wave inverter with optimizers costs roughly twice as much per watt as the SMA Sunny Boy string inverter.

But you should keep in mind these cost-per-watt figures assume each panel is working at max efficiency. If you build a string inverter in a shaded location and don’t put optimizers on your panels, your system will never produce at its rated output.

Another benefit of optimizers is individual panel monitoring. You’ll be able to track the production from each individual panel, which can help you spot defects and shading issues on a panel-by-panel basis.

What’s the Best Inverter + Optimizer on the Market?

Our preferred pick is the SolarEdge HD-Wave series, with the HD-Wave 7.6 kW model being our best-seller. The standard line features a broad range of options from 3.8 kW to 11.4 kW for residential systems, so you can scale the inverter to the size of your system.

The HD-Wave is small and lightweight, making it easier to install than other options in this category. It also boasts an industry-best 99% CEC weighted efficiency rating, so almost no power that flows through the system is wasted.

Read more about the HD-Wave in our review of the best grid-tied solar inverters on the market in 2019.

Micro-Inverters

What is a micro-inverter?

Enphase micro-inverters mounted on the back of solar panels.

A micro-inverter is an inverter that pairs with a single solar panel to manage the DC-to-AC power inversion for that individual panel. In micro-inverter systems, there is no centralized inverter. Instead, each panel is hooked up to its own micro-inverter.

Pros and Cons of Micro-Inverters

Each panel and micro-inverter pairing is essentially a self-contained single-panel solar electric system. This means that panels can be built in any configuration or orientation, and micro-inverter systems can be as small or as large as you need them to be.

Micro-inverters are similar to optimizers in that they isolate the output of each individual panel and enable panel-level monitoring. But they also provide an added benefit: the ability to start with a small-scale system that matches your budget, then expand down the road.

Let’s say you live in the average American household, which uses roughly 900 kilowatt-hours of electricity per month. What if you want to go solar, but only have the budget to offset a smaller portion of that usage up front?

With an initial budget of $2,000, you could start with five Enphase IQ7+ micro-inverters paired with five Astronergy 335W panels. That would allow you to offset about 25% of that energy usage.

You’ll start saving money immediately, since solar is cheaper than buying power from the utility, and you’ll be negating a portion of your bill. Later down the line, you can scale the system up to offset 100% of your household energy usage.

The tradeoff for this convenience is that micro-inverters are the most expensive option on a cost-per-watt basis. Once you scale into larger-scale systems, string inverters (with or without optimizers) are more cost-effective than micro-inverter systems.

Once you eclipse a certain system size (say 6-8 full-sized panels), we typically recommend switching over to a string inverter design as it will be the most cost-effective option.

What’s the Best Micro-Inverter on the Market?

Our go-to pick is the Enphase IQ7+ micro-inverter. It’s a 290W micro-inverter that is configured to work with either 60-cell or 72-cell panels (the two most common panel configurations). The 25-year warranty on the IQ7+ matches the industry-standard 25-year warranty on solar panels, so they’ll likely last for the entire life of your system.

Read more about the IQ7+ in our review of the best grid-tied solar inverters on the market in 2019.

How Do I Pick the Best Inverter For My System?

Your choice will likely be dictated by the constraints of your project. Pick a string inverter if you can build your system in full sunlight, or use micro-inverters if you need to start small and expand later. In most other scenarios, a string inverter with power optimizers is going to be your best bet to strike the right balance between price and efficiency.

For more info, grab our free solar inverter guide or call us up at 1-800-472-1142 to consult with our experienced solar design techs.

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String Sizing Guide: How Many Solar Panels Can I String Into My Inverter?

String Sizing Guide: How Many Solar Panels Can I String Into My Inverter?

Designing a solar electric system is a complex process. We’ve written guides on how to size a grid-tied system, as well as sizing a battery bank for off-grid systems, which give you a pretty good idea of how much solar energy you need to produce to offset your energy consumption.

But they don’t dive too deep into more complex sizing concepts, like picking compatible parts for your system and wiring the components together properly.

One common point of confusion is the concept of string sizing—how many panels you can wire into a single input on your inverter.

I wanted to write this article to explain the concept of string sizing, and break down the string sizing calculations we do to ensure your panel strings are the proper size to keep you running at maximum efficiency.

It’s worth noting that the grid-tied and off-grid systems we sell already take string sizing into account, so you won’t have to worry about this if you work with one of our designers.

However, we know that many of our readers are heavily inclined toward the DIY approach. Our goal is to equip you with accurate information to make informed decisions during your research and design process.

What Is String Sizing?

A panel string is a group of panels that are wired into a single input on your power inverter. String sizing describes the calculations we make to determine how many panels we should plug into one input for optimal efficiency.

A panel string is a group of panels wired into a single input on your inverter.

For example, this grid-tied system contains 24 Mission Solar 360W panels and one SMA Sunny Boy 7700W inverter. The inverter (appropriately called a string inverter) has three string inputs.

This system is designed to connect three strings of 8 panels each into those inputs (totaling 24 panels).

Why Does String Sizing Matter?

Inverters operate within a specific input voltage range, called the operating range. Your panel strings must output a voltage that falls within that range.

If the panels don’t supply enough voltage, the inverter won’t have enough power to turn on.

If too much voltage is supplied, you can damage your inverter and void the warranty.

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The operating range is simply the range in which your inverter will properly function. In this range, your inverter will turn on and deliver power to your appliances.

However, falling within the operating range just means the inverter is working — it doesn’t guarantee you’re getting the most power you possibly can out of it.

To really optimize output, you want to fall within a more narrow voltage range called the maximum power point (MPP) range. This is the sweet spot in which your inverter runs at the peak efficiency listed on its spec sheet.

Your goal is to size your panel strings to supply a voltage that falls within this maximum power point range.

Let’s look at how we calculate string size to achieve this goal.

How To Calculate String Size

String sizing calculations depend on the specific voltage of your panels and inverter, as well as outside factors like temperature.

Each panel has an output voltage. This is the voltage the panel sends to the inverter. We’ll need to look at a few different figures:

Open circuit voltage (Voc): The voltage supplied when the circuit is open—that is, when current isn’t passing through the circuit. This state occurs when the inverter isn’t powered on.

Max Power voltage (Vmp): The voltage of the panel after it is turned on and operating normally under load (current is flowing through the circuit).

Find these numbers on the panel spec sheet. It’s different for every panel.

On the inverter spec sheet, look for the rated MPP voltage range. This is the sweet spot for ideal operation that I mentioned in the last section.

Also take note of the max DC input voltage. We’re especially concerned about this, because if you exceed the max operating voltage, you’ll overload the inverter and potentially fry the equipment. (We’ve seen it, unfortunately.) Going over the max operating voltage will void the warranty on your inverter.

There is also a minimum DC voltage and a startup voltage requirement that needs to be met in order to turn on the inverter. Typically this won’t be an issue, since we want our strings to operate well above the minimum, up in the MPP range where it works at higher efficiency.

Alright, we’ve got our figures and it’s time to do some math. Let’s use that 8.64 kW grid-tied system I linked earlier as an example.

Mission Solar 360W panels have a Vmp of 39.28 and a Voc of 48.08, as listed on the spec sheet:

Open circuit voltage and max power voltage for Mission Solar 360W panels.

The SMA Sunny Boy 7700W inverter has a rated MPP voltage range of 270-480 volts. The operating range is 100-600 volts (look for minimum and maximum DC voltage on the spec sheet):

Operating range and maximum power point values for the Sunny Boy 7.7 kW string inverter.

Step 1: Find your minimum string size

First we want to calculate the minimum number of panels we should put in a string.

For that, take the low end of the MPP range (in this case 270V) and divide by the Vmp of the panel (39.28).

270V ÷ 39.28V = 6.87

The result is 6.87, which needs to be rounded up to the next whole number (since you can’t put a fraction of a panel on a string). So your minimum string size is 7 panels before temperature compensation.

Step 2: Find maximum string size that doesn’t exceed operating voltage

For maximum string size, we want to calculate against the max DC input voltage to make sure we don’t overload the inverter.

For this calculation, take the max DC input (600V) and divide by the Voc of the panel (48.08).

600V ÷ 48.08V = 12.48

This time we need to round the result down, since we’re trying to stay below a maximum threshold. So we come to 12 panels.

Again, this number is not final because we haven’t corrected for temperature yet.

Step 3: Check that max string size falls within MPP range

In step 2 we calculated that maximum string size to keep the inverter operational. We want to double check that this falls within our peak efficiency range as well.

For that, take the max string size calculated in step 2 (12 panels) and multiply by the Vmp of the panel (39.28).

12 ∗ 39.28 = 471.36V

We are checking that this falls under the top end of the MPP range (in this example, 480V). Since 471V is below our target 480V, everything checks out here.

If we had arrived at a number above the MPP range in this step, we would knock the max string size down by 1 and recalculate until we successfully fall within the MPP range.

Based on these calculations, we have a string size of 7-12 panels. But this doesn’t take temperature into account, which can have a significant impact on our figures (colder temperatures lead to a rise in voltages and hotter temperatures will lower voltage).

Step 4: Account for temperature in your location

We now want to ask the question: “would extreme temperatures cause us to fall outside a safe operating range?”

To do this, I go to Weather Channel’s site, weather.com, and enter the location where the system will be built.

Let’s say we’re in Boise, ID. Search for the location in the search bar:

Use the dropdown to set your units to Celsius. This will match the units on the panel spec sheet.

Then navigate to the Almanac with records and average temps in this location. I want to find the coldest ever day on record (to account for the absolute worst-case scenario). That’s the gray bar:

We use the coldest day on record to account for the worst case scenario in our string sizing calculations.

We find that the absolute coldest day on record in Boise is -33.3° C.

Now we need to go back to the solar panel spec sheet and look for the temperature coefficient of Voc, which measures the change in voltage per degree Celsius away from the Normal Operating Cell Temperature (NOCT).

These coefficients show how the voltage coming from our Mission Solar 360W panels changes as temperatures move further away from standard test conditions.

NOCT measures the panel’s voltage at a given temperature, when it’s tested in a climate-controlled environment.

For the Mission Solar 360W panels in our example, the NOCT is 44° C. We take the difference between the NOCT and the coldest day on record (-33.3° C) for a value of 77.3° C below the standard conditions.

The temperature coefficient on these panels is 0.280%/°C. This means that for each degree Celsius away from the NOCT, the panel will produce .28% more voltage.

We first need to multiply the Voc of the panel (48.08) by the temperature coefficient of Voc (.28%). Since the temperature coefficient is a percentage, move the decimal 2 places to the left to account for this in the equation:

48.08 ∗ 0.0028 = 0.134624

This gives the voltage change per degree Celsius, so we need to multiply by the temperature difference we found above (77.3°C):

0.134624 ∗ 77.3 = 10.406V

On a record-cold day in Boise, each panel will produce about 10.406 volts above its rated Voc of 48.08. We need to add those values together to get the true panel voltage on a record cold day:

48.08V + 10.406V = 58.486V

From here, multiply the true panel voltage by the max number of panels in the string (12) we calculated in step 2:

58.486 ∗ 12 = 701.83V

The total voltage of the array can peak at 701.83V on a record cold day! This is well above the max operating voltage of 600V, which means cold temps can push your array into territory that will cause damage to your inverter.

That’s obviously not ideal (did we mention you could fry your system?), so we need to make adjustments to max string size to bring this down to an acceptable level.

You want to start subtracting panels off the string until you fall within the operating range. Take the array voltage (701.83V) and subtract the true panel voltage (58.486V):

701.83V – 58.486V = 643.346V

Not good enough: it’s still above the 600V limit. We need to subtract one more panel:

643.346V – 58.486V = 584.86V

Perfect. We’re under the 600V max input threshold after accounting for the temperature extremes the array could reasonably be exposed to. Since we’ve removed 2 panels from our starting point, we arrive at a final max string size of 10 panels.

This is the magic number. Under these conditions, your string size should be capped at 10 panels. Any larger has the potential to permanently damage your array in extreme temperatures.

Right about now, hawk-eyed readers may be asking…

“This accounts for cold temperatures…what about excessively hot temperatures above the NOCT?”

NOCT tends to be measured at 44-46°C which is around 111-115° Fahrenheit. Most places don’t peak above this, although it certainly happens in some areas, especially close to the Equator.

Regardless, warm temps aren’t as much of a concern because they decrease voltage. Again, our primary concern is staying below the max input voltage so we don’t damage the inverter. Voltage drop due to warm temps just brings us further under the “danger zone.”

Extreme heat will affect minimum string size, though, and you may want to check that your minimum string size still falls within the MPP range for optimal efficiency. To do that, you follow the same calculations as above, but you need to use different values:

  • Use the panel Vmp in place of Voc.
  • Use the panel Temperature Coefficient of Pmax in place of Temperature Coefficient of Voc.
  • When it comes to calculating the true voltage of the panel, subtract the voltage compensation from the panel Vmp (instead of adding it to the panel Voc).

For example, the record high in Death Valley, CA is 56.7°C, which is 12.7°C above the NOCT. The Vmp is 39.28V and the Pmax temperature coefficient is -0.377. Here’s how the math would look in this scenario:

Vmp temp coefficient of Pmax = voltage change per ° Celsius

39.28 ∗ 0.00377 = 0.148

Total voltage difference for 12.7° C above NOCT

0.148 ∗ 12.7 = 1.8796V

Subtract from Vmp to arrive at true panel voltage on record-hot day

39.28 – 1.8796 = 37.4004

Multiply by minimum string size for total input voltage

37.4004 ∗ 7 = 261.8028

Way back in Step 1, we cited the low end of the MPP range as 270V and you can see 261.8V falls slightly below that range. The ideal would be to bump the minimum string size up to 8 panels.

However…this is accounting for the absolute hottest day on record in Death Valley, which is a sweltering 134°F! And the consequence here isn’t inverter damage, just a system that operates slightly below peak efficiency in extreme circumstances.

So really, you can see the concern here is pretty much non-existent. 8 panels is technically ideal for minimum string size, but 7 panels is not going to give you any trouble.

Wrapping Up

Whew…we made it! That’s our exhaustive guide to string sizing, for all you folks who love to get hands-on with your projects.

Remember, our complete system packages are built with proper string size in mind, which takes these complex calculations out of your hands. For help building a system that fits your needs, request a free consultation with our experienced system design team.

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Review: SolarEdge HD-Wave Inverter with Integrated Electric Vehicle Charger

Review: SolarEdge HD-Wave Inverter with Integrated Electric Vehicle Charger

Today we’re going to take a quick look at a new offering in our product line: the SolarEdge HD-Wave 7.6K inverter with an integrated electric vehicle (EV) charger.

SolarEdge is our default inverter choice for most grid-tied solar systems, and the 7.6 kW size is our best-selling model. You can read more about why we like SolarEdge in our review of the best grid-tied inverters on the market.

The model we’re looking at today has the exact same features as that best-selling model, with one addition: an integrated port to charge your electric vehicle. Check out the video to see how it works:

All of the guts for the electric vehicle charger are right in the box. There is no extra work involved to install the EV Charger. Just mount the inverter on the wall, plug in the charging cable and you’re good to go.

The best part about this inverter is that it’s flexible. The car charger works even if you don’t have solar installed. The inverter works even if you don’t need to charge an electric vehicle. Neither function depends on the other to work properly.

You can start with one purchase (either the solar system or the electric vehicle), then add the other down the line. There’s no extra wiring or circuit breakers to install, and you don’t need to fear incompatible equipment.

The charge cable is sold separately and can be added any time you purchase an electric vehicle.

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SolarEdge also plans to launch a 3.8 kW inverter with an EV charger. We stock the 7.6kW version in our warehouse, and the smaller configuration is stocked at SolarEdge and ready to ship on demand.

The 3.8 kW will be your choice if you want to get into a smaller system or just plan to add a few panels to your existing array.

With either option, the most interesting application we’ve seen for this product so far is building a solar power carport.

The basic idea: build the carport for shelter where you park, then mount the solar panels on top to start generating energy. The carport should be sturdy enough to double as a foundation for your system.

You can build the structure with your own design, or get a custom order from SunModo, a company that designs custom carports for solar applications.

Mount the HD-Wave with EV charger somewhere on the carport, and voila! You’ve got a nice little place to park, generate solar power and charge your electric vehicle.

It’s a simple but brilliant solution if you’re considering solar, and already have (or plan to buy) an electric vehicle. And it’s pretty easy to install as a DIY project, even by yourself.

Where traditional inverters can weigh 65 to 75 pounds, the new HD-Wave inverters only weigh about 25 pounds. The car charging cable (sold separately) only weighs about 12 pounds, and you simply latch it on when you’re ready to use it. One person can set up the whole system.

This is a fairly new product, but we’ve already seen some really interesting builds with these new hybrid units. We can’t wait to see what you come up with!

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Best Solar Inverters for Grid-Tie Systems (2019 Edition)

Best Solar Inverters for Grid-Tie Systems (2019 Edition)

What are the best solar inverters in 2019?

We recently published our recommendations of our favorite off-grid inverters you can buy for solar applications.

It quickly became one of the most popular articles on our site. So now we’re back with its counterpart: a review of the best solar inverters you can buy for grid-tie systems in 2019.

These are the inverters you would use in a traditional home or office system – any property that has access to power lines and can connect to the utility grid.

We put together a video to highlight our picks. You can also keep reading for more detailed analysis, current prices and key product specs.

Here’s our review of the best grid-tied solar inverters you can buy on the market in 2019:

Best Grid-Tied Microinverter

Best String Inverter with Optimizers

Best Grid-Tied String Inverter

Best Storage-Ready Grid-Tied Inverter

Why Do I Need an Inverter?

If you’re just getting into solar, let me quickly explain what an inverter does.

The inverter is like the brain of your solar system. It manages the flow of power throughout your system.

When panels collect energy from the sun, they generate DC (Direct Current). But home appliances use AC (Alternating Current).

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At its core, the inverter has a simple job: it converts captured DC power into usable AC power.

Beyond that basic functionality, some inverters have extra features that make them more suitable for specialty applications. Let’s take a look:

Best Microinverters for Grid-Tied Systems: Enphase IQ7+

  • Price: $158 apiece, which includes a mandatory Q cable for each panel. Total cost comes to 54 cents/watt.
  • Wattage: 290W
  • Peak Efficiency: 97.6%
  • Individual Panel Monitoring? Yes
  • Best for: starting with a small system and expanding in the future. Also great if you have multiple places to build on your roof and want to split the system into sub-arrays.

The concept of microinverters is simple: pair an inverter with every panel.

The benefits are fairly easy to understand as well. There are two cases where you should use microinverters:

  1. You want to start with a small system and be able to expand down the road.
  2. You want to monitor each panel independently.

In some ways, when you pair a microinverter with a panel, you’re creating a self-contained single-panel solar energy system. Each will produce power regardless of how many panels you have.

We recommend the Enphase IQ7+ Microinverter for these applications. As of the time of publication (January 2019), these are $142 apiece. You also need a mandatory Q Cable for each microinverter, which adds $16 per panel.

You would pair them with a panel ranging up to 300 watts, which will cost you another $150-$225 or more depending on panel selection.

Each inverter and panel pairing works out to around $350 (fluctuating by ~$50 depending on which products you pick). This does not include the cost of mounting or wiring the system.

Recommended Panel Pairings For The IQ7+:

Astronergy 335W or Mission Solar 310W

So how does the math look when you’re trying to build a full-sized system?

Let’s say it would take a $10,000 system to completely offset your energy bill, but right now, your budget is only $3,000.

If you want to cancel out a portion of that bill right away, you might get about 8-10 panels with microinverters on them. You’d start saving money on electric bills right away, and you can easily add on to it a few years down the road until you hit your target of 100% energy offset.

The ease of installation is another nice side benefit. Microinverters use standard AC wiring, which is cheaper and easier to work with.

In all, microinverters make it possible to get started with solar and build out your system at your own pace. But that scalability comes at a slightly higher price than other options.

If you have the budget to build a complete system from the start, we’d recommend going with a more cost-effective option: a string inverter.

Best String Inverter: SMA Sunny Boy

  • Price: $1725 (22 cents/watt)
  • Wattage: 7700W
  • Peak Efficiency: 97.5%
  • Individual Panel Monitoring? Not by default (you can add optimizers for extra cost, but you lose the Secure Power Supply feature by doing so.)
  • Best for: complete grid-tied systems in full sunlight.

A string inverter is a single unit that hooks into a string of solar panels. Our recommendation in this category, the SMA Sunny Boy, is sized to support strings in the range of 6-14 panels.

String inverters are your least expensive option, and they thrive in the right conditions.

The main issue with string inverters is that when shade falls on one panel, the efficiency drop translates to the other panels in the string. So if you have 10 panels in a string, and one gets shade, all 10 will drop to the reduced output of the shaded panel.

But what if you have space to build a system that will never fall under shade?

If you have land with plenty of unobstructed space, this is going to be the cheapest and most effective inverter for most systems.

If you live on a city block with buildings or trees casting shadows on your panels…not so much. You’d never get close to the expected output from your system.

But if you’re sure you have enough room to build away from obstructions, go with the SMA Sunny Boy inverter. It’s a reliable string inverter that is far cheaper than other options assuming you meet the requirements.

Depending on the model, the Sunny Boy inverters have either 2 or 3 inputs, which means you’ll have either 2 or 3 strings of panels wired to your inverter.

The SMA Sunny Boy also comes with a neat feature: a 2000 watt Secure Power System (SPS). The SPS is a feature unique to the SMA brand.

The SPS acts like a small backup power source in case of outages. While it’s not a long-term solution, the SPS powers a dedicated 120v outlet that can power up to 2000 watts during the day if there is solar power available.

You can also buy optimizers and pair them with the inverter. This will help mitigate the shade problem, but as a tradeoff, you lose the SPS functionality.

It makes sense to add the optimizer if you previously built an SMA system, then needed to retrofit the array due to new obstructions. Adding optimizers onto the panels would be easier and more effective than ripping out and replacing your whole inverter.

However, if your goal from the start is to get the most output from a partially-shaded array, we would recommend a different inverter for that purpose.

Best String Inverter w/Optimizer: SolarEdge HD-Wave

  • Price: $1875, plus mandatory P400 optimizers at $67 per panel. Works out to 42 cents/watt for a 24-panel system.
  • Wattage: 7600W
  • Peak Efficiency: 99%
  • Individual Panel Monitoring? Yes
  • Best for: a broad variety of grid-tied solar applications. You get the convenience of centralized design, paired the flexibility of panel-level monitoring. It’s the best mix of features and price.

Our best-selling residential grid-tied inverter is the SolarEdge HD-Wave line, a string inverter with optimizers. The classic HD-Wave line received a major update in 2019 with the introduction of the SetApp feature, which allows you to program and monitor your system from a phone app (rather than on the LCD screen).

This is our go-to grid-tied inverter option because it offers the best of both worlds. You get the lower cost of a central string inverter combined with the individual panel monitoring offered by microinverters.

For that reason, it works in a broad range of applications. In most cases, it’s simply the best combination of features and cost you can find in a grid-tied inverter.

The system is shade-tolerant thanks to the optimizers attached to each panel. And it’s cheaper than microinverters once you scale to at least 8 panels (the minimum string size compatible with SolarEdge inverters).

In the end, SMA and Enphase are tailored to a specific application. The SMA Sunny Boy needs full sunlight, and Enphase microinverters are more appropriate if you start with a small system.

For other grid-tied applications, our default recommendation is the SolarEdge line. It’s the workhorse of the industry: nothing too flashy about it, just versatile, reliable and easy to use.

Our most popular size is the SolarEdge 7.6 kW HD-Wave inverter, but they come in a range of 3.0 kW to 11.4 kW options for residential systems, with higher capacity options available for commercial use.

Best Grid-Tied Inverter With Storage Capacity: Outback Skybox

  • Price: $6,445
  • Wattage: 5000W
  • Peak Efficiency: 97%
  • Best for: grid-tied systems with energy storage, which protects against power outages and allows you to store power and use it later.

If you want to add battery backup to the mix, you’ll need a storage-ready inverter to manage your system.

Aside from protecting against emergency outages, energy storage has another purpose. You can take control of your power, storing it for later or sending it into the grid.

This is used in areas where the utility bills have time of use (TOU) charges or residential demand charges. Energy storage allows you to store and consume the power your generate. You can even sell excess energy back to the utility for a profit.

Our recommendation in this category is the Outback Skybox. It’s our favorite battery backup option because it checks all the boxes:

Ease of Installation

All components (inverter, remote control, breakers/load center and PV inputs) are included in one unit. Since all connectors for the PV array, the utility grid, and a backup generator are present in the main console, you only have to mount a single unit during installation.

This makes it far easier to install than other systems, which require you to mount and wire anywhere from 3-6 different components together for interconnection. The ease of installation is one of the Skybox’s key selling points.

Battery Flexibility

It works with any standard 48V battery bank. It’s more flexible than the competing StorEdge option from SolarEdge, which is only compatible with a single battery (the LG Chem).

Backup Generator Input

It has an input for a backup generator, in case you need to build a hybrid generator + solar system.

Works Without Batteries As a Standard Grid-Tie Inverter

It allows you to start as a pure grid-tie system and add batteries later without any additional parts or configuration changes. Other products don’t have this flexibility. Outback’s own Radian system requires you start with batteries, and the Magnum MicroGT will require additional components if you choose to expand into energy storage.

The Skybox’s versatility makes it our preferred pick for energy storage systems.

An Alternate Energy Storage Pick: Magnum MicroGT

Another good pick for storage-ready inverters is the Magnum MicroGT. It provides backup power like the Skybox does, but in micro-inverter form.

However, the MicroGT lacks the functionality to offset time-of-use charges and sell energy back to the grid. It also does not comply with the new smart inverter requirements in California and Hawaii.

These drawbacks prevent us from recommending the MicroGT all situations. The Skybox is simply a more complete and versatile product.

This article was updated on 2/13/2019. For our most current prices, take a look at the inverters page in our shop.

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What’s the Best Off-Grid Solar Inverter? (2019 Edition)

What’s the Best Off-Grid Solar Inverter? (2019 Edition)

What are the best off-grid solar inverters you can buy in 2019?

If you’ve spent any time researching solar energy, by now you’ve heard of an inverter.

The inverter is like your solar system’s brain. It manages your power flow, controlling two kinds of power.

DC—or direct current—power is the kind stored in batteries. It’s also the kind produced by solar panels.

But you can’t use DC power (directly) to power anything in your home. That’s where your inverter comes in.

Everything in your home uses AC—or alternating current—power. And an inverter takes DC power from your panels (or from batteries) and turns it into AC so it can be used for your fridge, lights, TV, and other household appliances.

Simple, right?

How is an off-grid inverter different from a grid-tied inverter?

A grid-tied inverter takes DC power from solar panels, turns it into AC, and sends it into the grid for credit.

Grid-tied inverters are simpler and easier to wire since there are usually only two main components—the inverter itself and your solar panels. (Some grid-tied systems are starting to incorporate energy storage, but most don’t have any batteries at all.)

But an off-grid inverter needs a battery bank to function.

How a grid-tied solar inverter works
How an off-grid solar inverter works

Here’s how it works: your solar panels feed DC power into the batteries. Then your inverter takes that power and “inverts” it, creating AC power for your home. This works essentially like a miniature power grid.

(In case you’re curious, no, your inverter won’t deplete your batteries provided your system is set up and designed right. The battery bank gets recharged by your solar panels and a charge controller, and by a backup generator in the winter months.)

As you might imagine, off-grid systems are more complicated, thanks to additional components like the charge controller, battery monitor, and additional AC and DC circuit breakers. All of these things tend to make off-grid systems more difficult to wire and install.

It can also be a challenge to buy off-grid equipment because there are a lot of associated accessories: remote controls, battery monitor, breakers and enclosures, surge suppressors, and so on.

Picking the right parts can be confusing enough—but there’s no more critical decision than buying the right inverter.

How to Pick the Best Off-Grid Inverter

Think About Size

The first thing to think about is how much power you need.

Fortunately, sizing off-grid inverters is straightforward if you know what appliances you’re going to use.

Add up the wattage of all your lights and appliances to calculate the number of watts you’d need if everything was used all at once. (No, you’re not likely going to use everything, but this is an easy way to be safe.)

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Don’t forget to consider the voltage—although most appliances run on 120Vac, some appliances, such as well pumps, require 240Vac. Example: Let’s say you need 1,000 watts for your fridge, 500 watts for lights, and 200 watts for your phone & TV. That adds up to 1,700 watts. In this case, we’d suggest a minimum inverter size of at least 2,000 watts to give you a little extra headroom. (After all, you may add appliances in the future.)

What’s the most popular size we sell? 4kW followed by 8kW. Different models and brands are available in various sizes and most of them can be stacked together for higher power output.

Consider Pure Sine Wave Instead of Modified Sine Wave

You may hear some manufacturers talk about pure sine wave inverters. You don’t need to understand exactly how these work—it’s enough to know that the power that’s put out by a pure sine wave inverter is “cleaner” than what you’d get from a modified sine wave inverter.

Pure sine wave inverters deliver higher quality power output, similar to (or better than) our power grid. Modified sine wave inverters are cheaper, but they deliver lower-quality power output.

For this reason, modified sine wave inverters can cause issues with certain appliances. Motors, pumps and compressors run hotter and wear out more quickly. Certain sensitive appliances like computers can be damaged, or they may not work at all. These inverters also typically cause background noise on a stereo, and reduced video and audio quality for certain TVs.

That’s why we don’t recommend modified sine wave inverters for most applications; most of our off-grid customers are use pure sine wave inverters to avoid these potential issues.

Need a quick way to tell the difference? Look at your inverter’s total harmonic distortion (THD) rating. THD is an indicator of power quality output and will be listed on the spec sheet of any decent inverter.Rule of ThumbTo avoid running into trouble, choose a pure sign wave inverter with THD of 5% or less.

Look at the Technical Specs

Here are some other technical specs to consider:

  • Efficiency. This is a measure of how much power from the batteries your inverter delivers to your home when it’s operating in perfect conditions. A good peak efficiency rating is around 94% to 96%.
  • Self-consumption, or no-load current draw. How much power will your inverter consume just sitting there? Obviously you want this to be as low as possible.
  • Surge capacity. How much short-term overload can the inverter handle before it “trips?” Some appliances, like pumps or fridges, need as much as 2x–3x their running power to start up.
  • Battery charger output. Many off-grid inverters include a battery charger, which is used to recharge your batteries during the winter months with a backup generator. The battery charger will have a rating, usually measured in amps. Most decent off-grid inverters will have a battery charger in the range of 50-100 amps DC.
  • Temperature range. Inverters are sensitive to extreme heat. Pay careful attention to the temperature range if you plan on installing your system in your garage or anywhere it could be exposed to temperature extremes.
  • Warranty. Warranties start at 1 year and typically range from 3-5 years, with a few manufacturers offering a 10 year warranty extension option.

You can normally find information on all these features on the product spec sheets. Check with your solar tech for help comparing and picking the right inverter.

Research Features

Your inverter may need special features. Look into these ones:

  • Battery charger. A charger allows your system to be charged from a backup AC generator. Most bigger inverters include this; these are called “inverter/chargers.”
  • Grid-tied capability. Some off-grid inverters have the added capability of feeding power into the grid, here are a few examples:
    • Outback FXR/VFXR
    • Outback Radian
    • Schneider XW+
    • SMA Sunny Island
    This capability is useful if the grid becomes available in the future, or if you are setting up a grid-tied system with battery backup.
  • Automatic generator start. Usually you’ll need an add-on accessory for this, although some inverters or charge controllers can take care of it.

Read Up on the Manufacturer

Knowing about the inverter manufacturer is also important. Check into their history and reputation. Off-grid inverters need to be on all day, 365 days a year, for several years at a time—so you’ll want to choose one from a manufacturer with a reputation for reliability.

In our experience, there are only a handful of companies making high quality inverters for this purpose:

Make Sure it Has UL Listings and Certifications

Off-grid inverters have a few different certifications required in the US, for safety and also to ensure code compliance.

Inverters for your home need to be UL 1741 listed. Mobile inverters for boats and RVs should carry a UL 458 certification. There are a few other requirements for different applications such as UL 1778 for uninterruptible power supplies and KKK-A-1822E standard for emergency services, such as ambulances.

There are other standards required outside of the US such as CSA 107.1 in Canada and IEEE 1547 used internationally outside of North America.

Don’t Forget Price!

You also need to look at the price of the inverter system (including all required components)—as well as the features you get for that price.

Make sure to compare the price of all required components, including the remote control, circuit breakers, mounting plate, and anything else required to install the system.

Another Good Option: Using a Pre-Wired Power Center

A power center is a pre-wired off-grid inverter system that includes everything you need: an inverter, charge controller, remote control, and circuit breakers.

Most of the power centers we sell also include some additional components for monitoring and protection, including a battery monitor, and surge suppressors.

We assemble power centers with all of these components, and then wire them up and test on our workbench to make sure the system is wired correctly and working.

Buyers, especially those looking to DIY, love power centers because you can add them to a solar installation by making only a few final connections. (We even label the connection points to help make it even easier.)

The Best Off-Grid Inverters in 2019

Your choice of inverter really depends on your size requirements and the application, but here are some of our favorites:

Our Pick For: Best Small Off-Grid Inverter

Best inverter for self-contained micro-systems: Morningstar SureSine

Morningstar SureSine

  • 300 watts 120Vac output
  • 12Vdc battery bank

This inverter is small. At just 300 watts of output power, it can handle lights, charging phones and tablets, and an efficient TV—and that’s about it.

But the SureSine is renowned for being extremely durable. It’s also used for industrial applications, powering remote equipment in harsh conditions all over the world.

It’s efficient, with very low self-consumption, which makes it ideal for smaller systems like a hunting cabin.

It’s also perfect for industrial remote power systems that require a small amount of 120Vac power.

Our Pick For: Best Off-Grid Inverter for Cabins & Small Homes

Best off-grid inverter for small cabins: Magnum MS-PAE

Magnum Energy MS-PAE

  • Two models: MS4024PAE and MS4448PAE
  • 4kW-4.4kW 120/240Vac output
  • 24-volt or 48-volt battery bank

The MS-PAE inverter series comes in two sizes: 4kW 24-volt, or 4.4kW 48-volt.

Magnum Energy inverters are fairly easy to set up and use. They have good surge capability and powerful battery chargers. They also have a nice Magnum Panel system that includes a back plate and breaker panel (to make a complete power center).

Installing these inverters on a Magnum Panel bumps up the standard warranty from three years to five.

There are accessories available, including a battery monitor, automatic generator start (AGS) and MagWeb kit for remote monitoring.
MS-PAE Magnum Power centers have been our best selling power centers for years, both for off-grid cabins and for small homes.

Multiple MS-PAE inverters can be stacked together—up to 4 inverters, or 17.6kW total—which makes this inverter also suitable for bigger off-grid homes.

The 4kW 24-volt model can work with smaller battery banks and solar arrays; that’s ideal for cabins.

Magnum inverters are available in a wide range of sizes, and they are relatively affordable and easy to set up, which makes them a great choice for off-grid cabins and homes.

Our Pick For: Best Large Off-Grid Inverter

Best off-grid inverter for large-scale applications: Schneider Conext XW+

Schneider Conext XW+

  • Two models: XW+ 5548 and XW+ 6848
  • 5.5-6.8kW 120/240V output
  • 48-volt battery bank

The XW+ inverter comes in two sizes: 5.5kW or 6.8kW output power. Both work with a 48-volt battery bank.

Multiple inverters can be stacked together, and groups of three can be combined for three-phase power systems.

Schneider offers several accessories including a power distribution panel, automatic generator start, and battery monitor. The Schneider XW+ system really excels with bigger, multi-inverter systems.

Schneider supports multiple clusters of inverters for large industrial and commercial applications, up to 102kW output power. They also support Lithium batteries.

All of these features, plus the ability to stack clusters of inverters, make the XW+ our choice for large off-grid power requirements.

BONUS PICK! Best Inverter for Grid-Tied Systems with Battery Backup

Best off-grid inverter that can convert to grid-tie battery backup systems: Outback Radian

Outback Power Radian

The Outback Radian is an off-grid inverter that can also tie into the grid to sell your excess power.

This is the ideal option if you want the combination of battery backup and grid-tied solar, or if you’re off-grid but you think access to the grid will become available in the future.

The Radian inverter system includes advanced software, called Optics RE, for remote monitoring and control, allowing you to monitor your system, get alerts about any faults, and change settings remotely. It can also control generators for basic automatic start and stop.

Currently this is the only battery-based inverter approved for grid-tied interconnection throughout the US. It’s also the only grid-tied battery backup inverter available that complies with the newest standards in CA and HI for connecting grid-tied systems.

It’s available in two sizes, 4kW or 8kW, and multiple inverters can be stacked together for up to 80kW of power.

This is our best selling inverter for grid-tied with battery backup; most customers opt for either one or two of the 8kW inverters (either 8kW or 16kW.)

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Say Hello to the Next Generation of Grid-Tied Solar Power Inverters

Say Hello to the Next Generation of Grid-Tied Solar Power Inverters

Every grid-tied solar power system needs an inverter, and there are a lot of different ones on the market. Today we’ll help you narrow down your choice, because we’re focusing on the best of the bunch: the HD Wave Inverter from SolarEdge.

The SolarEdge HD Wave is one of the most innovative grid-tied inverters on the market today: 50% smaller than most inverters and with an efficiency rating of 99%. It sports a number of improvements over traditional inverters, and SolarEdge spent a lot of time developing it to be the next leap forward in the industry – likened to the jump from “fat-backed” televisions to flat-screen plasma displays: it’s a huge innovation.

But before we dive into the details of the HD Wave and what makes it so great; let’s take a look at why the inverter plays such an important role in a Solar System setup.

Why do we need an inverter anyways?

The inverter is the “brain” of your solar system. It manages your power flow, taking the DC power produced by the solar panels and “inverting” its current into AC power for your appliances and home electricity.

DC power is “unidirectional,” meaning it flows in one direction. This is what your solar panels produce when they convert the sun’s heat and light into electricity.

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AC power “alternates” by changing the direction of the power flow periodically. This is the type of energy your home uses to power its appliances and devices.  

The more efficient your inverter is, the more you can take advantage of the sun’s energy, and the HD Wave Inverter is currently the most efficient grid-tied inverter on the market.

what-an-inverter-does

SolarEdge Leads the Pack for Innovation

This revolutionary new grid-tied inverter doesn’t come without a fair share of competition. There are hundreds of other inverter manufacturers in the world, so SolarEdge had to truly change the game in order for their design to come out on top.

SolarEdge’s innovations proved so revolutionary, in fact, that they were awarded the Intersolar Award in 2016. This prestigious award is granted to companies deemed instrumental in driving forward progress in the solar industry.

The HD Wave Inverter is not only more efficient, but it’s also considered to be one of the most reliable systems on the market. SolarEdge stands by their new technology by providing lifetime system monitoring services and a 12-year standard warranty.

comparison

6 Reasons Why the HD Wave is the New Gold Standard for Inverters:

  1. Smaller and lighter for easy installation. The small form factor of the HD Wave Inverter makes it easy for DIY installers. It weighs less than 25 lbs (regular inverters weigh much more, 50-100 lbs!).  
  2. Rated at 99% efficiency by the California Energy Commission (CEC). Most traditional inverters, when converting DC to AC, will lose 3-5% efficiency. But the HD Wave Inverter only loses 1%—allowing your system to produce more energy on average. Improvements include:
    • New digital processing technology
    • 16x less magnetics than other inverters
    • Newly optimized capacitors that improve power output.
  3. The SafeDC System: Limits each panel’s output to 1 volt. (discharging capacitors and shutting down power optimizers). This makes it safe for installers, firefighters, and maintenance personnel who are working on or around your panels.
  4. Four-button touch panel interface on the front of the HD Wave allows for smooth operation. This allows for easy setup and adjustment of your system.
  5. 12-year standard warranty ensures the system holds up over time, and can be repaired or replaced. This can be upgraded to a 20 or 25 year warranty for added peace of mind.
  6. Lifetime system monitoring (household energy consumption & production app) – sign into your SolarEdge account and keep track of your system diagnostics, PV panel performance and power flow from your computer or phone. You can even track faults or issues that crop up in real time, so you can make repairs and adjustments as soon as possible.

The SolarEdge HD Wave Inverter is available for most solar systems, sized at 3.8kW5kW6kW, and 7.6kW Watt modules, with 10kW and 11.4kW sizes coming soon, allowing it to be used for most grid-tied solar power systems.

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