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Why You Should Oversize Your PV Array By 10-20%

Why You Should Oversize Your PV Array By 10-20%

Why You Should Oversize Your PV Array For Your Inverter

When designing a solar system, it is often smart to size components so that the panels supply 10-20% more wattage than the rating of the inverter. In this article, we’ll explain how oversizing your PV array can maximize your system’s overall efficiency.

Welcome to our solar tech tips series! In this article, we’re going to take a look at a concept that can create a lot of confusion during the system design process: oversizing your PV array for your inverter.

First, the basics: solar panels and inverters both have a wattage rating. For example, a 315W solar panel produces 315 watts, and a 290W micro-inverter can put out a max of 290 watts of power, if it’s available.

When the panel produces more power than the inverter can handle, the excess wattage is “clipped.” Anything above the 290W rating can’t be processed by the inverter, so if the 315W panel is producing at its rated output, 25 watts are wasted by the input limitations of the inverter.

Knowing all this, you might make the reasonable assumption that the panel wattage shouldn’t exceed the inverter wattage, because wasting power is generally a bad idea…right?

But that’s not quite true.

When designing a solar electric system, you’ll get the most bang for your buck if you oversize your panels by 10-20% in relation to your inverter. 

It’s counter-intuitive, but it’s true. Here’s why.

Why You Should Oversize Your PV Array

In real-world conditions, the panel rarely produces at its rated output. There are two main reasons for that: 

  1. Efficiency Loss: real world factors like temperatures, shading and pollution affect the amount of light hitting your panel. This can cause the panel to produce below its rating.
  2. Production Curve: The array doesn’t produce a consistent amount of power throughout the day. Production is a curve, with less output during the morning and evening, and peak production at “solar noon.” During off-peak periods, the panel doesn’t produce as much as its wattage rating.

Let’s look at each of these points in more detail.

Standard Test Conditions vs. Real-World Conditions

When manufacturers test panels to give them a rating, they do so in ideal conditions:

  • Indoors, at a controlled temperature (about 77°F)
  • With a given amount of solar irradiance (1000 watts per square meter) 
  • At an ideal 90° angle of incidence (light shining directly on the panel)

These standard test conditions measure what the panel is capable in a perfect environment, but the real world rarely delivers these ideal conditions.

In reality, there are a number of factors that can reduce panel efficiency:

  • Hot temperatures
  • Tilt angle of the array
  • Time of day / sun’s position in the sky
  • Cloud cover and pollution

Under real-world conditions, a 315W panel rarely produces 315 watts of instantaneous power.

Our general rule of thumb is to ballpark 10% efficiency loss to account for real-world operating conditions. The true number changes based on your local environment, but 10% gives us a good baseline estimate.

Sun Hours & Peak Sunlight Window

For a solar panel to reach peak output, the sun has to be angled so it is directly perpendicular to the array, allowing it to absorb the maximum amount of light possible.

That only happens during a narrow window in the middle of the day. As the sun moves across the sky, the angle changes so that less light strikes the panels. This causes the panels to produce less power.

A map of average sun exposure across the United States.

We use the term sun hours to describe this concept. “Sun hours” refers to the amount of time the sun is in the right position in the sky so that the array can generate power. Sun hours are measured based on an irradiance of 1,000 watts per square meter—the same rating used to test panels under standard test conditions.

Most places in the US get between 4-6 sun hours per day on average, and all of the meaningful production from the panels comes within this short window. The production graph is a curve where production ramps up as the sun comes out, hits a peak when it is straight overhead, then falls off again into the evening.

The horizontal line represents the input limit of the inverter. Any production above the line (the light orange area) is clipped, or wasted.

The blue area below the line represents untapped potential production. In these periods, the inverter is capable of more throughput, but the panel is not supplying enough wattage to make full use of the inverter’s potential.

Our goal with system design is to balance out clipped production with “lost” potential production. On the graph, notice how the area of clipped production and lost production are roughly equal. 

By oversizing the array, you will make better use of your inverter’s capacity, producing more power overall. You want to find the “sweet spot” where you get the most overall production possible per dollar spent on your system – even if that means clipping a bit more power.

There’s another benefit to oversizing that takes advantage of this principle. Most electrical service panels can handle up to 7.6 kW input from solar. Anything larger makes the install more complicated, as you have to either derate the main breaker, or tap into the utility line side.

If you don’t want to tackle a complex install, it might be smarter to oversize your array on a 7.6kW inverter to extend the production window, so that you generate more power in the mornings and evenings, squeezing out that extra bit of production to bring you up to 100% energy offset for your property.

Guidelines for Oversizing Inverters

When designing your system, a good rule of thumb is that your solar panels should be 10-20% larger than your inverter. In hot climates, that can be extended up to 30%, due to greater efficiency losses from heat.

Two real-world examples:

For micro-inverters, we usually pair the 290W Enphase IQ7+ with a solar panel in the 320W-350W range.

For string inverters, the SolarEdge HDWave 7.6kW inverter can be paired with a 8360W-9120W solar array. For example, you could use 3 strings of 335W panels, with 9 panels in each string, for a total of 9,045 watts on a 7,600-watt inverter.

Note that the manufacturers recommend a much broader range in both cases—Enphase suggests 235W-440W panels for the IQ7+, and SolarEdge specs a max of 11,800 watts on their 7.6kW HD-Wave. These guidelines spec what the inverters can safely handle, but we recommend the narrower ranges above to help people maximize their production per dollar spent on their system. Keep in mind that this will vary depending on your climate and other factors that affect production.

Need help with the design process? Request a free consultation with our team. We’ve designed more than 10,000 systems since we came online in 2002, and we can help you navigate challenges like array oversizing to design the best possible system for your needs.

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With the 30% Solar Investment Tax Credit Stepping Down After 2019, Now Is The Time To Go Solar

With the 30% Solar Investment Tax Credit Stepping Down After 2019, Now Is The Time To Go Solar

2019 Solar Investment Tax Deadline: What You Need To Know

  • The 30% investment tax credit for going solar drops in value after 2019.
  • It’s not enough to buy the system before the end of the year. To claim the credit, your system must be fully installed.
  • Solar systems take weeks to design, ship and install – so now is the time to start if you want to meet the deadline.

2019 is the last year to claim the full 30% investment tax credit for going solar.

The tax credit is a major incentive that puts money back in your pocket when you file your taxes. If you install the system before the end of 2019, you should be eligible to claim the full credit. 

But if you wait until after 2019, you’ll get less money back from the credit, which ultimately means you’ll spend more money when you do decide to go solar. 

To help you get as much value as possible out of your switch to solar, we put together a quick update on the tax credit changes to tell you exactly what you need to do to complete your project before the deadline hits. 

As you’ll see, going solar is a long and involved process. You’ll need to leave enough time to design your system, file a permit, ship the equipment, and build the system—all before the December 31st deadline. 

If you’re looking to take advantage of the full 30% credit, we urge you to get started now so the project doesn’t drag on and cause you to miss the cutoff date.

This article assumes you’ve been considering going solar and are generally familiar with the solar tax credit. If this is all new to you, check out our simple introduction to the topic:

2019 Deadline To Claim the Federal Tax Credit

The deadline to claim the full 30% solar tax credit is December 31st, 2019.

But what needs to be done before the deadline to be eligible?

It turns out the requirements are slightly different for residential and commercial installations.

Residential systems must be fully installed by the deadline to be eligible. To claim the tax credit on your return, you must complete your installation before the end of the 2019 calendar year.

For commercial systems, you just need to start installing before the end of 2019. The equipment needs to be shipped and you have to break ground on the project before the deadline—but unlike residential projects, it doesn’t need to be finished to be claimed on your return.

What You Need To Do To Make the 2019 Solar ITC Deadline

Designing and building a solar system isn’t a project that happens overnight.

Between planning, design, permitting, shipping, installation, and final inspection, it can take weeks—if not months—to make it through the whole process.

We can tell you from experience that December is our craziest time of year. We always get a surge of people who scramble to build their system before the end of the year so they can claim the credit on their next tax return.

But oftentimes they procrastinate and miss the deadline, because they underestimate how long the process takes.

So if you want to hit the 2019 deadline and claim the full 30% tax credit, we recommend getting started ASAP. Here’s our overview of how long you can expect each step in the process to take:

Research & Planning: 1-2 weeks

First you need to decide whether solar is right for you. In this phase, you’ll research some basic questions like:

These are a few of the most common questions people have about solar power, but it is certainly not a complete list. You’ll likely spend a decent amount of time doing this preliminary research before you’re ready to talk to a design technician.

Everybody goes through the research phase at their own pace. But if you want to move things along in time to claim the full 30% tax credit, we’d recommend you carve out 1-2 weeks for research. That’s enough time to answer common questions, do the math on ROI, and decide if going solar makes sense for you.

System Design: 1-2 weeks

In this step, you’ll connect with our design techs for a guided design consultation. We’ll look at factors like energy usage, local climate, and build site considerations. With this info in mind, we’ll design a system that is tailored to your energy usage and local sun exposure.

Once we have a design in place, our design tech will send you a quote. You can review this quote and request adjustments if necessary.

Plan to budget at least a week for this phase—more if the design goes through a round of revisions. It’s a collaborative process and there will be some back-and-forth communication between you and your design consultant.

Permitting: 2-4 weeks

Permitting is often the most time-consuming part of the process. Before you can build, you’ll need a permit approved by your local building authorities. 

This involves filing a permit request with product spec sheets and a wiring diagram attached. They may also require a site visit by certified inspectors before you can move forward.

The average timeframe here is about 2 weeks, but it can be longer depending on how responsive your local building departments are. We’ve seen permits stamped in just a few days, while others get delayed in the permitting process for several weeks.

Sourcing & shipping: 3+ weeks

We need time to pack and ship your equipment. Most components are stocked in our warehouse, while less common items are ordered on demand from the manufacturer, which extends the shipping time frame. 

Leave at least 3 weeks for distribution—more if we need more lead time to coordinate back orders with the manufacturer.

Installation: 1-2+ weeks

Depending on the complexity of the system, and your experience level with projects like these, it’s possible to completely install your system over the span of a weekend.

However, it’s more likely that DIYers take a bit more time to figure out the process and make sure they do each step correctly. After all, your system lasts for 25 years—it’s important to take time during installation to get it right.

DIY installs are typically completed over the span of a few weekends, so we would advise you to budget at least 2 weeks for this. It could be a bit faster if you hire an installer—just make sure to schedule them to install it when your shipment arrives, so the system isn’t gathering dust in your garage.

How Much the Investment Tax Credit Can Save You

Wondering what kind of impact the expiration of the tax credit will have on the cost of your system? Let’s look at a few real-world examples.

The average American household uses about 900 kWh of energy each month. Let’s see what it would cost to completely offset that usage, and how much you stand to get back from the 30% tax credit. 

This chart is broken out into grid-tied and off-grid systems, with the option to install it yourself or hire a contractor to do it for you at $1/watt. In all cases, we’ve assumed $1,000 for fees associated with shipping and permitting.

Ready to Go Solar?

If you want to claim the full 30% text credit before it reduces in value at the end of 2019, now is the time to get started on your project.

Fast-track your solar project by requesting a consultation with one of our experienced design technicians. We’ll evaluate your needs and connect you with a rep who can design your system and get your project moving forward.

If you want to get started ASAP, you can always give us a call at 1-800-472-1142.

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How to Add Battery Backup to an Existing Grid-Tied Solar System

How to Add Battery Backup to an Existing Grid-Tied Solar System

How to Equip a Grid-tied Solar System With Battery Backup

  • AC Coupling: Splice your AC wiring to add a storage-ready inverter and batteries
  • DC Coupling: Splice your DC wiring to add a storage-ready inverter and batteries
  • Inverter Replacement: Replace existing inverter with a storage-ready inverter

We’ve noticed a surge of calls lately from people looking to add battery backup to their existing grid-tie solar system. 

Many of these calls come from our home state of California, where PG&E has announced rolling blackouts to limit the impact of wildfires. With the prospect of scheduled blackouts looming, solar owners have been pushing to add battery backup to their systems to keep the lights on during grid outages.

Unfortunately, this process isn’t as easy as simply hooking up a new battery bank. Grid-tie inverters are designed to convert DC (direct current) from solar panels, but they are not designed to integrate with a battery bank. You’ll typically need to add new components to make your inverter work with your batteries.

This article will explore the 3 different approaches you can take to add energy storage to an existing grid-tied system:

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  1. AC Coupling
  2. DC Coupling
  3. Replace grid-tie inverter with storage-ready inverter

Method #1: AC Coupling

Grid-tied inverters need the power grid to operate—they constantly sense grid voltage and frequency and will shut off if it falls out of range. 

In an AC coupled system, the grid-tied inverter is paired to an off-grid inverter and battery bank. The off-grid inverter provides a second power source, which effectively tricks the grid-tied inverter into staying online. This allows you to charge your batteries and run essential appliances during a power outage.

The best option for AC coupling is the Outback Radian. The newest firmware supports frequency shift AC coupling, which will work with any inverter certified to UL 1741 SA standards. 

This feature causes the off-grid inverter to shift its frequency to control the output of the grid-tied inverter. The Radian limits the power coming in from the solar array when needed to prevent overcharging the batteries.

Here are the basic sizing guidelines for picking an inverter:

  • The Radian should have at least 25% higher nameplate capacity than the grid-tied inverter.
  • The GS8048A can AC couple with grid-tied inverters rated up to 6 kW (5 kW max for Fronius inverters)
  • The GS4048A can AC couple with grid-tied inverters rated up to 3 kW (2.5kW max for Fronius inverters)
  • Requires MATE3s remote with updated firmware for both the inverter and remote

See the Outback site for more info on using AC coupling to add battery backup to an existing gid-tied system.

Pros of AC Coupling

This is the easiest way to retrofit your system, especially a microinverter system. The battery bank connects to the Radian, which is installed between the grid-tied inverter and your load panels. The existing grid-tied inverter does not need to be removed.

Cons of AC Coupling

Strict guidelines for inverter and battery size make the process of sizing the addition a challenge. The system will perform poorly or not work at all if the inverter or battery bank are undersized. In addition, if the existing grid-tied inverter is large, an AC coupled system can get very expensive.

Compatible With:

  • Most grid-tied inverters on the market (anything listed to UL 1741 SA)

Method #2: DC Coupling

In a DC-coupled system, the solar array is connected directly to the battery bank using a charge controller. 

This is how off-grid systems work, and it could be done to a grid-tied system if they are using a 600-volt string inverter. This works with the SMA Sunny Boys, many Fronius inverters, or any other 600-volt string inverter.

This Morningstar 600-volt charge controller is designed to retrofit grid-tied systems with batteries. It can be combined with any one of our pre-wired power centers that doesn’t have a charge controller.

The 600V charge controller would be installed between the existing PV array and your grid-tied inverter. It includes a manual switch to switch between grid-tie and off-grid modes. The downside of this method is it can’t be programmed—the switch has to be physically turned to start charging the batteries.

The battery-based inverter can still automatically turn on and power your critical appliances, but the PV array won’t charge the batteries until the switch is turned. So you have to remember and be on site to turn on the solar charging. Otherwise, you might find your batteries are drained and you won’t be able to recharge from solar.

Pros of DC Coupling

In comparison to AC coupling, DC coupling works with a broader range of off-grid inverters and battery bank sizes. 

Cons of DC Coupling

The manual transfer switch means you have to be available to initiate the PV charging. If you forget or aren’t there, your system will still provide backup power, but the battery bank won’t recharge from solar until someone manually flips the switch on the controller.

Compatible With:

  • Most residential string inverters rated for 600 Volt max input

Replace Your Grid-Tie Inverter With a Storage-Ready Inverter

The last option is usually the most expensive: you can remove your existing grid-tie inverter and replace it with a storage-ready inverter instead.

This approach is going to be the most flexible option—it works for all existing grid-tie systems. There are a handful of inverters on the market designed specifically to accommodate energy storage for grid-tie systems:

  • The Outback Skybox can replace many SMA, Fronius and other 600V string inverters
  • The StorEdge can replace standard SolarEdge inverters (comes in 3.8kW and 7.6kW models)
  • Microinverters would need to be removed and replaced with any storage-ready system

Ideally, you want to replace your existing inverter with one that is about the same size and can use the same array wiring.

In many cases, this solution is preferable to adapting your existing system with AC or DC coupling because these inverters are designed from the ground up with energy storage in mind. They include some cool features, like storing energy and selling it back to the utility during peak time-of-use (TOU) periods to take full advantage of your local net metering policy.

This approach is tough with micro-inverters because it takes more work to rip out the old ones and retrofit every panel with a replacement. The labor is a bit more expensive and time-consuming, so an AC-coupled solution is often a better alternative for microinverter systems.

Pros of Replacing Your Inverter

  • Works for any system
  • Storage-ready inverters come with additional features

Cons of Replacing Your Inverter

  • Most costly option, especially for microinverters

Compatible With:

  • All systems

Wrapping Up

Retrofitting solar systems with new equipment can be tricky because of all the different equipment options and various methods for incorporating energy storage. New equipment can change the electrical characteristics for the entire system, and that could introduce faults if the components are not designed to work with each other properly.

If you need help picking the right products to add battery storage to your existing grid-tied system, drop us a line. We have been designing solar since 2002 and have more than 10,000 systems under our belt. Call us up at 1-800-472-1142 or fill out this form to request a free consultation with a member of our design team. We’re happy to help you work out the details.

If you’d rather go at your own pace, no problem! Click the image below to grab a free copy of our Solar Battery Guide.

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Solar Panel Size Guide: How Big Is A Solar Panel?

Solar Panel Size Guide: How Big Is A Solar Panel?

Standard Solar Panel Sizes

Traditional solar panels come in two common configurations: 60-cell and 72-cell. The standard dimensions for each option are:

  • 60-cell panels: 39″ x 66″ (3.25 feet x 5.5 feet)
  • 72-cell panels: 39″ x 77″ (3.25 feet x 6.42 feet)

One of the first questions people ask when they go solar is: “where am I going to build my system?” Solar arrays take up quite a bit of space, and not every property has room for them.

This quick guide will cover standard solar panel sizes and explain how to figure out how many panels you need in your system. From there, you can work out the total array size to see how much space the system will take up on your property.

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Standard Solar Panel Dimensions

Standard solar panels come in two common configurations: 60-cell and 72-cell.

An individual solar cell is a 6” x 6” square. 60-cell panels are laid out in a 6×10 grid. 72-cell panels are laid out in a 6×12 grid, making them about a foot taller.

  • 60-cell panels: 39″ x 66″ (3.25 feet x 5.5 feet)
  • 72-cell panels: 39″ x 77″ (3.25 feet x 6.42 feet)

These are the standard solar panel sizes for most residential and commercial installations, give or take an inch on either side. (There’s going to be a bit of variation because manufacturers use different frame sizes.)

Standard Solar Panel Sizes

There are other panel size configurations on the market, but they are much less common. For example, Panasonic offers 96-cell panels which measure 41.5” x 62.6”. 

However, the standard 60-cell and 72-cell panel sizes are by far the most common in the industry.

Solar Panel Size Chart

How Big Is the Average Solar Array?

The average American uses 867 kWh of electricity each month. It would take a 6.5 kW solar array to offset 100% of that usage.

The 60-cell solar panels we currently stock range from 285W to 315W, and our stock of 72-cell panels ranges from 335W to 375W. We can figure out approximately how many panels it would take to build a 6.5 kW (6500-watt) system:

  • 6500W / 285W = 22.8 (23 panels)
  • 6500W / 315W = 20.6 (21 panels)
  • 6500W / 340W = 19.1 (20 panels)
  • 6500W / 375W = 17.3 (18 panels)

An average-sized solar system will contain 18-23 panels depending on the efficiency of the panels you use. 

Here’s how that translates to physical system size. Let’s compare the least efficient panels (285W / 60-cell) to the most efficient (375W / 72 cell) to get a sense for how much space the array might take up:

375W 72-cell panels (9×2 array)

29.25 ft. x 12.83 ft. = 375.38 sq. ft.

285W 60-cell panels (8×3 array)

26 ft. x 16.5 ft. = 429 sq. ft.

The average size of a solar array, based on national average energy consumption in the US

In total, an average-sized solar system will take up 375 – 429 square feet. That system can be mounted on your roof, or on a ground mount somewhere on your property. The exact size will depend on panel wattage and the layout of the array.

How Big Are Portable / RV Solar Panels?

The other use case to look at is small panels for mobile / remote use. These are the panels used for RVs, boats, and remote applications like solar-powered streetlights.

Unlike traditional 60 and 72-cell panels, which are standardized across the industry, smaller panels come in a wide range of sizes. Tiny 5-watt panels take up less than 1 square foot of space, while our Solarland SLP190 (a popular choice for remote off-grid applications) approaches a full-size panel at 32” x 62”.

Picking the right panels for your boat or RV comes down to making the most out of the limited space available to you. Though full-sized panels can certainly work on the road, you often won’t have the space to mount them, so most people with RVs or boats need a smaller option. Typically these panels come in standard 12-volt or 24-volt output.

If you’re looking for panels for your RV or boat, we’ve covered several good options in our article highlighting the best portable solar panels for remote/mobile use.

How Much Do Solar Panels Weigh?

In addition to physical size, people often ask us how much solar panels weigh. Panels can be quite heavy and it can be a challenge to lift them on to your roof, especially if you are working alone.

As a rule of thumb, we tell people that full-sized panels weigh between 40-60 pounds. It varies a bit based on the products used by the manufacturer. Here’s a chart that shows the weight for full-sized panels we currently stock:

The real challenge with lifting panels is not so much their weight, but the fact that their physical size makes them awkward to carry. 

One person can manage a 60-cell panel, but it’s generally safer to enlist two people to carry 72-cell panels because they are over 6 feet tall. They can easily sway and cause you to lose balance, especially in windy conditions, so we advise everyone to err on the side of caution.

If you need help lifting panels on to your roof, you can also build scaffolding and/or use a mechanical lift to support the weight of the panels.

Still Stuck? Get Custom Design Help

Still have questions about system design? Call us up at 1-800-472-1142 or fill out this form to request a free consultation. We’ll walk you through system sizing, layout, and other considerations to help you navigate the design process.

If you’d rather do the research on your own time, grab a free copy of our Solar Panel Buyer’s Guide, which tells you everything you need to know about picking the right solar panels for your project.

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Install of the Month – July 2019

Install of the Month – July 2019

Every month, we highlight our favorite customer projects in our Install of the Month feature. These galleries give our visitors an idea of what to expect from the DIY solar process.

Worked with us to build a system and want to show it off? Submit your install for a chance to have your system featured on our blog! We’ll send a WSS care package your way if we feature your project.


This month’s featured project comes from Jonathan B. and family, who installed a 6.6 kW roof-mount system on their home in Missouri. Jonathan started out with a quote from a local solar installer, but soon realized he had the DIY background to do most of the work himself, which would save quite a bit of money if he was willing to put in the legwork.

Jonathan turned to online guides and YouTube videos to teach him what he needed to know about managing his own solar installation. He was meticulous about researching every aspect of his project to make sure he had all the details planned out before taking the leap with his purchase.

That planning paid off in a big way. Jonathan saved thousands on his project by doing most of the work between himself and his friends, only hiring an electrician at the end to inspect the wiring and approve the system for interconnection.

Here’s what he had to say about tackling his DIY solar installation:

What solar system type did you Install?

Grid-Tied

Did you have any previous DIY experience?

My friend and I remodeled my basement putting in an egress window and I did a lot of the electrical myself watching youtube and learning from an electrician friend of mine.

What was the most difficult part of the installation?

The paperwork was most certainly the most difficult part. If I had it to do over again I would have hired a company to do that for me. I overcame it by just continuing to tackle it in small size pieces until it was done.

How many helpers did you have?

I had a friend with general construction experience that helped me throughout. Then the day we hung panels we hired two more friends from work to lift the panels. Then I also had an electrician to check everything when I was done.

Did you hire a contractor?

Just my friend with the carpentry experience and the electrician at the end

Were there any unforeseen additional parts or tools you needed?

Yes- though mostly it was because I was just trying to get my head around the project. I ended up taking back $400+ of materials moral of the story Wil Burlin knows best and just do what he says and you’ll be fine.

How long was the full installation process?

4 days + waiting on our utility and city to inspect and turn on.

How did it feel to get your solar project finished?

Amazing! We are so excited. Our first bill was $8!! So exciting to be producing our own electricity!

Who else did you consider before choosing Wholesale Solar?

We were in contract with a local installer but then I got sense knocked in to me as I considered how long it was going to take to pay off. Then we remembered Wil and Wholesale and reached out to him. We picked up where we had left off a few years ago and now here we are!

What was your total solar install costs? (Ball Park)

$12,796.45

How much did you save on your taxes?

$3,838.94. I also got a utility rebate of $3,307.50 so you could subtract that directly from the install costs.

Components in Jonathan’s system:

Jonathan's Solar Breakdown:

  • System Cost: $12,796 including installation
  • Yearly System Output: 9,623 kWh per year
  • Federal Tax Incentive: Qualifies for $3,838 U.S. Federal Tax Credit
  • Utility Rates: 10.9 cents/kWh

It’s Your Turn

Thinking about making the switch to solar? Download our Getting Started Guide. We’ll walk you through everything you need to know about buying a solar energy system that covers your needs.

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Monocrystalline vs. Polycrystalline Solar Panels: Understanding Solar Cell Technology

Monocrystalline vs. Polycrystalline Solar Panels: Understanding Solar Cell Technology

Mono vs. Poly Solar Cells: Quick Facts

  • Monocrystalline solar cells are more efficient because they are cut from a single source of silicon.
  • Polycrystalline solar cells are blended from multiple silicon sources and are slightly less efficient.
  • Thin-film technology costs less than mono or poly panels, but is also less efficient. It is mainly used in large-scale commercial applications.
  • N-Type cells are more resistant to light-induced degradation than P-Type cells.
  • PERC Cells add a reflective layer to give the cell a second oppportunity to absorb light.
  • Half-cut cells improve solar cell efficiency by using smaller ribbons to transport electrical current, which reduces resistance in the circuit.
  • Bifacial solar panels absorb light on both sides of the panel.

Solar manufacturers are constantly testing new technologies to make their panels more efficient.

As a result, solar manufacturing has branched into a wide range of cell technologies. It can be confusing to try to figure out why you should pick one option over the other.

Ever wondered about the difference between monocrystalline vs. polycrystalline solar panels? Or N-type vs. P-type cells? You’re in the right place. This article will give a high-level overview of the major solar cell technologies in play and explain the pros and cons of each.

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Monocrystalline vs. Polycrystalline vs. Thin-Film Solar Panels

The first set of terms describes how solar cells are formed out of raw materials.

Traditional solar cells are made from silicon, a conductive material. The manufacturer shapes raw silicon wafers into uniformly-sized silicon cells.

Solar cells can either be monocrystalline (cut from a single silicon source) or polycrystalline (from multiple sources). Let’s look at the differences between the two options.

Solar cell technology comparison

Monocrystalline Solar Panels

Monocrystalline solar panels contain cells that are cut from a single crystalline silicon ingot. The composition of these cells is purer because each cell is made from a single piece of silicon.

As a result, mono panels are slightly more efficient than poly panels. They also perform better in high heat and lower light environments, which means they will produce closer to their rated output in less than ideal conditions.

However, they cost more to produce and that higher cost is passed on to the buyer. Mono panels are a bit more expensive than poly panels of the same wattage.

The manufacturing process for mono panels is also more wasteful than the alternative. Mono panels are cut from square silicon wafers and the corners are shaved off to make the distinct cell shape shown in the picture below. 

Monocrystalline solar panels have a dark, uniform look.

Lastly, mono panels have a uniform black look because the cells are made from a single piece of silicon. I personally think these look better than poly panels, but obviously, that is just a matter of preference.

Polycrystalline Solar Panels

Polycrystalline solar cells are blended together from multiple pieces of silicon. Smaller bits of silicon are molded and treated to create the solar cell. This process is less wasteful because hardly any raw material is thrown out during manufacturing.

The blended makeup of the cells gives poly panels their iconic blue color. If you look at them up close, you’ll see the texture and color is uneven due to the way the cells are made.

Polycrystalline solar panels are blended from multiple pieces of silicon.

Poly solar panels are slightly less efficient than mono panels due to imperfections in the surface of the solar cells. Of course, they’re cheaper to manufacture which means they cost less for the end user.

Thin Film Solar Panels

The majority of solar panels deployed today are made from either monocrystalline or polycrystalline solar cells.

There is a third type of solar technology, called thin film panels, which are usually deployed for large-scale utility projects and some specialty applications. Thin film panels are created by depositing a thin layer of conductive material onto a backing plate made of glass or plastic.

Thin film panels typically don’t see use in residential installs because they’re much less efficient than mono or poly panels. With roof space at a premium, residential customers go with more traditional crystalline silicon panels to maximize production from the space available to them.

However, thin film technology is less expensive to manufacture, and it becomes a more cost-effective option at a larger scale. For commercial and industrial projects without any space restrictions, the lower efficiency of thin film technology doesn’t really matter. Thin film panels often end up being the most cost-effective option in these situations.

In addition, if you’ve ever seen flexible solar panels on an RV or boat, thin film technology is what makes those possible. 

Because they are (as the name implies) much thinner than a traditional silicon wafer, the thin film can be deposited onto plastic to create flexible solar panels. These panels are especially nice for RVs and mobile use when you might not have a flat surface to mount the panel.

N-Type vs. P-Type Solar Cells

The previous section covers the process by which raw material is formed into silicon wafers.

This section has to do with the process by which those wafers are treated to turn them into a functioning solar cell that can generate an electrical current.

What are P-Type Solar Cells?

P-type cells are usually built with a silicon wafer doped with boron. Since boron has one less electron than silicon, it produces a positively charged cell. 

P-Type Solar Cells

P-type cells are affected by light-induced degradation, which causes an initial drop in output due to light exposure. This has historically been the most common treatment method for solar cells.

What are N-Type Solar Cells?

N-type cells are doped with phosphorus, which has one more electron than silicon, making the cell negatively charged. 

N-Type Solar Cells

N-type cells are immune to boron-oxygen defects, and as a result, they are not affected by light-induced degradation (LID). As you might expect, these are positioned as a premium option because they degrade less over the life of the panel.

Here are a few examples of N-type panels:

Most of the panels we sell use P-type cells, which can degrade a little faster, but still perform well for 30+ years. 

When you consider the lower cost of P-type cells, it typically pays to go with a cheaper module that degrades a little more, as opposed to a substantially more expensive panel with slightly less degradation. But that assessment may change as N-type technology advances and costs drop over time.

Other Differences in Solar Cell Technology

PERC Cells

PERC stands for Passivated Emitter and Rear Cell technology. PERC cells are distinguished by an extra layer of material on the backside of the solar panel, called the passivation layer.

PERC Solar cells

Think of the passivation layer like a mirror. It reflects light that passes through the panel, giving it a second chance to be absorbed by the solar cell. More solar radiation is absorbed by the cell, which results in a higher efficiency panel.

PERC cell technology is gaining traction because the inclusion of the passivation layer doesn’t add huge manufacturing delays or expenses. The efficiency boost more than justifies the extra step in the manufacturing process.

Aleo Solar has a good article that gives more context on the history of PERC technology as well as more technical info about how it works.

Half-Cut Cells

Half-cut cells are exactly what they sound like: solar cells cut in half.

The smaller size of half-cut cells gives them some inherent advantages, mainly (you guessed it) improved efficiency over traditional cells. 

Solar cells transport electrical current through ribbons that connect neighboring cells in a panel. Some of this current is lost due to resistance during transport.

Because half-cut cells are half the size of a traditional cell, they generate half the electrical current. Lower current between cells means less resistance, which ultimately makes the cell more efficient.

In addition, half-cut cells can be more shade-tolerant. When shade falls on a solar cell, it not only reduces the production from that cell, but every other cell connected to it in series as well. 

A traditional solar panel may have 60 solar cells, wired in series. If shade falls on one series of cells, you can lose one-third of that panel’s production.

In contrast, a panel made of half-cut cells would have 120 half-cut cells, wired in series/parallel with two strings of 60 cells. Shade that falls on one string would not affect the output of the other, which minimizes production loss caused by shading issues.

Bifacial Solar Panels

Bifacial solar panels are panels that are treated with conductive material on both sides. They’re designed to take advantage of reflected sunlight that hits the back side of the panel.

Bifacial solar panels

In theory, this sounds like a great idea because you are doubling the conductive surface area of the panel. But in practice, bifacial panels call for a much more expensive mounting setup to get any real benefits from the technology.

The system needs to be mounted in an elevated position so that there is clearance below the array. It also calls for the right reflective material beneath your array, like white rocks below a ground mount or a white roof.

Bifacial panels are significantly more expensive to install, and at this point, the minor efficiency gains don’t do enough to recoup the extra installation costs. Bifacial panels aren’t quite ready for the limelight, though that may change as the technology develops further.

Which Panels Should I Choose For My Project?

You might be feeling some information overload right now. It’s nice to understand the nuances of the manufacturing process, but ultimately there’s one question on everyone’s mind: “which one should I buy?”

Our advice is always this: look at cost-per-watt and go from there.

To make a fair comparison between products, divide the panel cost by its rated wattage. The result tells you how much power you will generate per dollar you spend. For example:

Going with Mission Solar would mean fewer panels in your array, but the overall system will cost more due to the higher cost-per-watt on the panels. (Both of these are mono solar panels. In this case, the price difference is because Mission Solar panels are made in America and Astronergy is imported from overseas.)

Once you evaluate pricing on a level playing field, then consider whether other factors (like cell technology or country of origin) play a factor in your decision.

For more info, check out our free solar panel buying guide linked below.

Download our free solar panel buying guide!

Install of the Month – June 2019 (Part 2)

Install of the Month – June 2019 (Part 2)

Every month, we highlight our favorite customer projects in our Install of the Month feature. These galleries give our visitors an idea of what to expect from the DIY solar process.

Worked with us to build a system and want to show it off? Submit your install for a chance to have your system featured on our blog! We’ll send a WSS care package your way if we feature your project.

We featured an Install of the Month winner earlier this June, but this system built by Jerry R. was too good to pass up. So we’re back for round two!

Jerry’s project stands out thanks to knowledge and commitment to the DIY approach. He’s done quite a bit of DIY work in the past and was eager to tackle this solar build as his next project.

Along the way, he even built a trolley to help him lift panels on to the roof—a solution he custom designed and built exclusively for this project. Alden, his design consultant, was impressed by his ingenuity and enthusiasm throughout the process. So were the inspectors, who gave Jerry high marks for his professional craftsmanship when they signed off on the build.

Jerry was eager to share his experience going solar, so we’ll let him take it from here!

What solar system type did you install?

Grid-Tied

Did you have any previous DIY experience?

I have a ton of DIY experience. I have installed a 16 KW Generac Standby generator, a complete 16 zone 70 head underground sprinkler system, a complete kitchen addition from the ground (I mean foundation) up, an On-Demand Water heater, zoned HVAC control, a Smart Home system and an electric car charging station to name a few. I have completed all of these projects 99% by myself… electrical, plumbing, framing, sheetrock, you name it, I’ve done it. Even with all that, this is the first time I was up on my roof for an extended period of time… and I am not great with heights.

What was the most difficult part of the installation?

Getting the first rail just right. The roofer had done a really lousy job of installing the shingles so there was not a straight line to be had. This made installing the FlashFoot 2 a challenge. I devised a means of determining distance and square to overcome this. I took about 4 hours to install the first 42 foot rail and only about 1.5 hours once I got to the fourth 42 foot rail. I chose to do all of the splicing in place. You can’t carry a 42 foot rail by yourself and not break something.

The other difficult part was panel lifting and installation. For this I designed and built a trolley (see pictures). The trolley was designed to work with a standard extension ladder. I used a double pulley system and casters that would ride on the ladder sides to reduce friction. One person could easily lift a 40 lb panel to as high as the ladder will go. With this trolley and the help of two neighborhood kids we were able to install 31 panels in about 6 hours.

How many helpers did you have?

I did all of the work myself except for the actual panel installation. I had two helpers for that… one on the ground using the self designed trolley to move and lift the panels, and one on the roof with me to install the panels. That worked very well. The first one took us about 45 minutes to get the process right. The last 5 took us only 8 minutes each. I guess we learned something…

Did you hire a contractor?

No!!!

Were there any unforeseen additional parts or tools you needed?

Safety harness, shingle lifter, trolley parts, knee pads.

How long was the full installation process?

I did everything myself so I took my time.
  • Permitting: 5 days
  • Material Receipt Panels May 2, 2019
  • Material Receipt Remainder: May 6, 2019
  • Combiner 3 and Disconnect installation: 16 hours
  • Line side taps and Transfer Switch panel work: 6 hours
  • 1″ Main Trunk (75′) and wire pull (8 #10 plus ground): 24 hours
  • Garage roof rails: 10 hours
  • Main roof rails: 21 hours
  • Four #10 branch circuits: 40 hours
  • 31 Microinverter installation: 3 hours
  • 31 Solar Panel installation: 6 hours
  • Commissioning: 3 hours (including Enphase setup)
  • Inspections: 3 hours
  • Project Complete: May 30, 2019

How did it feel to get your solar project finished?

Well, I was very happy… first that it was done and second, how nice it looked. All of the inspectors commented on the quality of the workmanship. Now I am looking forward to many years of clean, reliable solar power.

Who else did you consider before choosing Wholesale Solar?

I considered a number of turn-key installers but felt I could do this myself. I found Wholesale Solar on-line. I was skeptical but Alden Silber was my rock. He was with me through the whole process and I am very grateful for his guidance and assistance.

What were your total solar install costs? (Your best ballpark estimate)

$28,952

How much did you save on your taxes?

I hope to save about $9,000 this year on my taxes.

Components in Jerry’s system:

Jerry's Solar Breakdown:

  • System Cost: $28,952 including installation
  • Yearly System Output: 13,455 kWh per year
  • Federal Tax Incentive: Qualifies for $8,685 U.S. Federal Tax Credit
  • Utility Rates: 14.9 cents/kWh

It’s Your Turn

Thinking about making the switch to solar? Download our Getting Started Guide. We’ll walk you through everything you need to know about buying a solar energy system that covers your needs.

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“Free Solar Panels” Are a Bad Deal. Here’s Why.

“Free Solar Panels” Are a Bad Deal. Here’s Why.

Ever seen a solar company promote an offer for “free solar panels?”

The offer sounds too good to be true…and unfortunately, it is.

Yes, there are (legitimate) installers that will put free solar panels for your home. But the catch is that they require you to enter into a solar lease or power purchasing agreement (PPA).

These offers entice people with a no-cost way to go solar. But when you examine the contracts, they heavily favor the solar installer over the 25-year life of the system.

This article explains the economics behind leases and PPAs to show how the offer of “free solar panels” ultimately costs the end user money in the long run.

What are Solar Leases / Solar PPAs?

Solar leases and PPAs offer people a way to go solar with no up-front cost.

Under a solar lease, the installer builds a system on your property and charges you a monthly fee to lease the equipment from them. You pay a flat monthly fee and get to use 100% of your system’s production.

Power purchasing agreements (solar PPAs) are similar, except instead of renting the equipment for a set fee each month, you buy power from the installer at a flat rate per kWh. So if you use less power than your system produces, you don’t have to pay for any excess generation.

Drawbacks of Solar Leases & Solar PPAs: “Free Solar Panels” Aren’t Free

Under both agreements, the main drawback is that you don’t own your system. The installer owns it.

They structure it this way so that they can claim the Federal Tax Credit and any local incentives for going solar. As of 2019, that represents a 30% credit on your total costs to go solar.

A system that costs $10k rewards a $3k tax credit to the system owner. Under leases and PPAs, it is the installer—not you—who gets to pocket this credit. You miss out on the largest financial incentive for supporting renewable energy.

solar guide

Free Federal Tax Credit Guide

Learn More »

Yes, they’ll put free solar panels on your roof, but they also reap most of the long-term value from owning the system. They make more than enough profit over the life of the system to recoup the cost of equipment—savings that should end up in your pocket.

A Better Way To Finance Your System

Of course, we understand why leases and PPAs are appealing. You get the benefits of going solar immediately, like making a positive impact on the environment and locking in a flat electric rate for the next 25 years.

Leases and PPAs let you enjoy the benefits of going solar without the up-front cost. But there’s another financing option that gives you a much better return on investment: a personal loan from your bank or another 3rd-party lender.

Solar leases and PPAs are essentially high-interest-rate loans from a solar installer. You tend to get better rates and terms from your bank, especially if you’ve been a long-time customer.

But the major distinction is that by taking out a personal loan, you are the owner of your system. This allows you to claim the 30% tax credit for going solar—which can immediately be applied to your loan balance to accelerate the payback schedule, if you so choose. (Check out the video below if you want to know more about how the tax credit works.)

The Hidden Cost of “Free Solar Panels”

So how does buying solar stack up to leases and PPAs?

We did some math to figure out the return on investment into solar under four different payment plans:

  • cash purchase
  • personal loan
  • solar lease
  • solar PPA

Our math is based on the cost to own this 5.2 kW system under each of the four payment plans. We assume the cost of electricity starts at $0.16/kWh and raises by 3% each year for 25 years (the length of a solar panel warranty).

For the purchase and personal loan options, the value of the 30% tax credit is included because you own your system. We also factor in a $1/watt installation charge for these options.

For leases and PPAs, we did not add the installation charge because it is included as part of the package. We also leave out the tax credit, because that belongs to the solar company that owns the system.

See how all four payment plans stack up over 25 years:

As you can see, buying your system outright represents the best value over 25 years, even though the cash payment puts you in the red up front.

The next best option is taking out a personal loan. The initial cost is $0, but interest payments eat into energy savings for the first 7 years until the loan is paid off. It quickly rebounds after year 7 when the owner starts to keep 100% of the energy savings from their system.

After that, we come to solar leases and solar PPAs. Though they don’t cost you anything up front, the value is dampened by the solar company taking a cut of the savings each month. By the end of the warranty period, leases and PPAs have chewed up more than half the potential energy savings as profits for the solar installer.

This is why we strongly recommend choosing a personal loan over a solar lease or PPA If the option is available to you. An offer of “free solar panels” may be tempting, but it could potentially cost you $25K in energy savings over the life of the system.

We want everyone to go solar—but we also want them to fully reap the benefits. If you need to finance your system, personal loans are by far the superior option to solar leases or PPAs.

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Net Metering Guide: How the Utility Credits You For Solar Power

Net Metering Guide: How the Utility Credits You For Solar Power

Net Metering: A Quick Summary

Grid-tie solar system owners receive credit for sending electricity into the public utility grid. They use those credits to offset their energy bill. This agreement is outlined by your utility’s net metering policy, which sets the rates at which interconnected solar customers buy and sell electricity.

When you go solar, you need a way to store the energy generated by your panels. The easiest method is to hook into the utility grid to store energy and save it for later use.

But to do that, you’ll need to agree to terms with the utility company that outline how you are credited and billed for power. These policies are referred to as net metering (or net energy metering) agreements.

Under a net metering agreement, the grid acts as energy storage for the solar homeowner, banking the power they generate so they can use it later. The utility tracks your meter to record your net energy usage (energy consumed minus energy sent to the grid) so they can bill or credit your account based on overall usage.

Net metering agreements benefit both parties. The homeowner has a way to store solar power for later use, and the utility benefits because the extra supply of electricity smooths the power demand curve and prevents outages.

solar guide

Free Solar Permitting Guide

Learn More »

Each utility company has different terms and conditions, so it’s important to contact them before going solar to figure out how the connection process works. This article covers some of the most common agreements so you know what to expect.

Types of Net Metering Agreements

What is Net Metering?

In broad terms, net metering is an agreement with the utility company that allows you to get credit for solar energy sent into the grid. The utility gives you a credit for the solar electricity you generate, and you can use those credits at any time to draw power from the grid.

The utility monitors the meter on your property to track how much energy you use. If you withdraw more than you produce, you pay the utility for any extra usage.

If you produce more power than you use in a given month, any excess production is credited to your account and rolled over to future months. These credits can be “banked” for periods of low production, meaning credits you earn in August can be used in December when the days are shorter and the weather is worse.

Under most net metering agreements, the utility will reimburse you for excess generation, either through a check or energy credits toward your future bill. However, most utilities pay reimbursements at a wholesale rate (vs. awarding credits at retail rates), so most folks choose to take the credit.

What is a Feed-In Tariff?

Most net metering agreements use one meter to track net energy consumption (energy used minus energy generated from solar) and bill everything at a uniform rate.

Under a feed-in tariff, the utility installs two meters: one for the power you use, one for the power you generate. Each meter is billed at a different rate.

Feed-in Tariffs incentivize solar adoption by making the utility pay higher rates for solar energy sent into the grid.

Feed-in tariffs are typically implemented by local governments to incentivize people to switch to renewable energy sources; the utility pays a premium rate to encourage solar adoption. For example, you might buy power at $0.12/kWh, but sell excess power to the utility at $0.25/kWh.

What is Net Purchase and Sale?

This is essentially the opposite of the feed-in tariff structure. The utility still installs two meters, but they charge electricity at retail rates and buy it from you at reduced wholesale rates.

Under this billing structure, the utility only pays their “avoided cost” for anything you feed into the grid—the cost they would have paid to generate that electricity.

This is not as good a deal for the consumer as the regulated feed-in tariffs, but it’s still decent because you can receive payment for surplus generation.

What is Aggregate Net Metering?

Aggregate net metering allows for multiple meters on a property to be offset by a single solar system.

Let’s say you live on a ranch property with your home, a barn, and a workshop, each with separate meters. Under this agreement, all three meters are counted toward the total net energy use on the property.

This works the same as ‘standard’ net metering. The only difference is that it allows you to track more than one meter on a property.

What is Virtual Net Metering / Community Solar?

Aggregate net metering allows a single customer to offset multiple meters on his or her property.

Virtual net metering differs in that it allows multiple customers to participate in net metering with a shared solar energy system.

Under this policy, shared residences like apartment buildings can build a centralized solar system, with individual tenants metered and billed under their own account.

Similarly, neighborhood residents can build a community solar farm to supply power to multiple homes in the neighborhood. Those who choose to buy into the community solar program receive an ownership stake in the shared system. They would be entitled to credits and/or reimbursement in proportion to their ownership stake in the system.

What are Time-of-Use Rates?

Lastly, your net metering policy may be affected by time-of-use (TOU) rates. Under a TOU policy, the utility charges more for electricity during peak demand periods, when people are home from school and work in the evening.

Where applicable, net metering calculations are affected by TOU rates. Solar generates energy during off-peak hours (when the sun is out during the day), so that production is credited at a lower rate. When you flip on lights in the evening, you are billed a higher rate for usage during peak periods.

The result is that you can generate enough energy to cover your usage and still end up paying a bill, because you pay a higher rate to use energy in the evenings than the rate you are credited for producing during the day.

To counteract this, you can invest in an energy storage system that allows for TOU offset. A small battery bank can store daytime production for use during peak periods. By drawing power from your battery bank (instead of the grid) in the evening, you avoid paying higher rates during peak usage periods and maximize the value of your solar production.

Net Metering Caps and Restrictions

Some utilities have restrictions and caps on their net metering policies. These restrictions are in place to level out supply and demand, and to prevent people from taking advantage of the policies purely for profit motive (since you can make money by selling off surplus energy).

These restrictions may include:

  • System size caps: either a concrete limit (systems up to 1 MW) or a percentage (125% of consumption)
  • Technology restrictions: outdated or inefficient technologies may not be eligible
  • Credit rollover limits: credits can expire and be surrendered to the utility if not used within a certain timeframe
  • Property type: residential, commercial and industrial properties may have different policies
  • Renewable energy source: Aside from solar, net metering policies may apply to wind, hydro, fuel cells, biomass, geothermal, and other renewable energy sources.

Next Step: Understand Your Local Net Metering Policy

Thinking of going solar? Contact your local utility a call and ask about their net metering policies. Many have their policies published online.

They’ll explain how they credit you for solar energy produced, which is important to understand if you want to get the most out of your system.

For more help on permitting and interconnection with the utility, grab a copy of our free solar permitting guide!

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Install of the Month – June 2019

Install of the Month – June 2019

Every month, we highlight our favorite customer projects in our Install of the Month feature. These galleries give our visitors an idea of what to expect from the DIY solar process.

Worked with us to build a system and want to show it off? Submit your install for a chance to have your system featured on our blog! We’ll send a WSS care package your way if we feature your project.

This month’s winner is Michael from Davidson, NC. As a carpenter and engineer, taking on a DIY solar build was right in his wheelhouse. 

Although the heat delayed the installation somewhat, they still managed to wrap up the project in less than 10 days. When all was said and done, they built a system that will offset over $1,500 in electric bills every year.

We connected with Michael to ask some questions about how the project went. He was kind enough to pass along this time-lapse video of the entire project from start to finish, which gives a great snapshot of what to expect from the DIY solar process:

What solar system type did you install?

Grid-Tied

Did you have any previous DIY experience?

I am a carpenter, engineer and seasoned DIY’er.

Before moving back to NC we renovated a 90 year old Colonial in Hartford Connecticut including all new electrics. Installing a Solar System seemed to be much more fun than replacing knob and tube!

What was the most difficult part of the installation?

The installation itself was not difficult. It helped to prepare by watching the videos and the material available from WS and SolarEdge online. The heat, however, became a difficult factor limiting the work time on the roof to the mornings. I feel we maximized our time by working inside to install the inverter, wiring the switches and panel etc., when it got too hot on the roof.

The most difficult process overall was the permitting prior to installation. There were simply no clear directions on what the process is for a homeowner functioning as the general contractor. It was a “learn as you go” experience for us and with a few more clear directions a lot of time and resources could have been saved.

How many helpers did you have?

My father, an electrical engineer, joined me from Germany and was a great helper. My wonderful wife Alison made a lot of phone calls during the permitting. Our 3 daughters provided a lot of moral support and served Gatorade during the installation.

Did you hire a contractor?

NO -the only trade we had to contract was a structural engineering analysis of our roof structure, which was required for the permit.

Were there any unforeseen additional parts or tools you needed?

We decided during the preparation to buy some 2 by 4’s and OSB boards for scaffolding to make the installation easier and safer. This is due to our 45 degree roof angle.

How long was the full installation process?

It took 7 days to install the system. It took 1.5 days to build and remove the scaffolding.

How did it feel to get your solar project finished?

GREAT! It really all went very smoothly and better than expected. Seeing the first production number in the APP was amazing! Obviously we check it every day since.

One goal for this project was to show our children that the sun can produce our own energy, which can greatly impact the future of our planet. The fact that our 5 year old Josie now points out potential good solar roofs as we drive through our town is simply the feeling of great accomplishment!

Who else did you consider before choosing Wholesale Solar?

In preparation for this project we read some literature and checked out several online retailers. The fact that WS offers different pre-configured packages triggered the call to discuss our desired system in more detail.

After the first call with Wil there was no question that we wanted to work with WS. The very competitive pricing combined with the technical expertise and helpfulness was what we were looking for.

What were your total solar install costs? (Your best ballpark estimate)

$16,500

How much did you save on your taxes?

$4,950

Components in Michael’s system:

Michael's Solar Breakdown:

  • System Cost: $16,500 including installation
  • Yearly System Output: 14,722 kWh per year
  • Federal Tax Incentive: Qualifies for $4,950 U.S. Federal Tax Credit
  • Utility Rates: 10.24 cents/kWh

It’s Your Turn

Thinking about making the switch to solar? Download our Getting Started Guide. We’ll walk you through everything you need to know about buying a solar energy system that covers your needs.

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