Category: Solar Panels

Bifacial Solar Panels Aren’t Quite Ready For Primetime

Bifacial Solar Panels Aren’t Quite Ready For Primetime

Over the past few years, there have been some interesting developments in the solar industry focused on getting the most production possible out of solar panels. One such development is bifacial solar panels.

Since solar panels come in standardized sizes (either 60-cell or 72-cell), manufacturers are looking for creative ways to increase a panel’s efficiency without increasing its size. With bifacial solar panels, manufacturers have developed solar cells that absorb sunlight on both sides to maximize production from light that reflects on the back of the panels.

Bifacial panels are a creative idea, however they are not as appealing as they first sound. In this article, we’ll explain why we think it’ll be at least a few more years before they catch up to traditional solar panels and start to make sense for more solar projects.

What are bifacial solar panels?

Let’s start with the basics.

Traditional solar panels can only absorb light that hits the front of the panel. Bifacial solar panels produce power from light that hits both sides of the panel.

Using dual-sided solar cells gives bifacial panels more surface area to absorb sunlight, and therefore, higher efficiency in the same form factor.

Why would you use bifacial solar panels?

When sunlight hits the face of the panel, not all of it is absorbed on the first pass. Even the most efficient panels only have an efficiency rating of 20-23%, which means around 80% of the potential energy is “lost” as it passes through the PV cells.

Bifacial solar panels seek to solve this problem. By installing the panels over a reflective surface, the light can bounce back through the panel a second time, giving the cells on the backside of the panel a second chance to capture and convert energy.

Since the panel has a second opportunity to reabsorb sunlight, bifacial panels enjoy increased efficiency over their traditional counterparts. Given that bifacial panels provide higher output from the same form factor, it’s easy to see why the solar industry is excited about them.

BUT… (yes, there is a “but”).

Why aren’t bifacial solar panels a good idea (yet)?

Bifacial solar panels are designed to improve efficiency and output more power, but they come at a higher cost—not only for the panels, but for associated materials to mount them properly.

For bifacial panels to work properly, the back of the panel must remain unobstructed. That means you’ll pay a bit more to build a racking system that gives enough clearance from the ground or roof surface where they’re mounted. The materials for these mounts will cost more than a standard roof mount system like the IronRidge XR100.

In addition, you’ll need to create a reflective surface behind the array, either by using reflective white rocks, a shiny coat of white paint, or a layer of reflective material like a TPO roof membrane

The extra costs associated with properly mounting bifacial panels negates any money you might have saved from the slight efficiency bump. Bifacial panels really only make economic sense for large (utility-scale) solar projects. Right now, for residential and small-scale commercial projects, it’s more cost-effective to simply buy a few more panels if you need to squeeze a bit more efficiency from your array. 

The verdict: bifacial solar panels aren’t quite ready

Bifacial solar panels are a great idea, and as they have time to improve with more research and development, we think it will make sense to stock them at some point.

But as of right now, they are not quite ready for primetime. Without the right racking setup, there is no guarantee you will get the efficiency boost from the backside of the panel. And the extra mounting costs to meet those requirements don’t justify the modest efficiency boost for small-scale installations.

We will need to see some combination of improved efficiency, lower price, and/or less restrictive mounting requirements for us to feel comfortable recommending bifacial solar panels for residential installs.

Bifacial panels may make some sense for large-scale commercial installs. Trackers are more economical to install on a large scale, and they allow for more dense PV systems, which helps make the most of the space available. The land-use efficiency can be beneficial for larger projects, since utility-scale systems are often designed to maximize production from the limited space available for the installation.

Need help picking the right solar panels for your project? Learn which panels are best for you with our free Solar Panel Buyer’s 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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Mission Solar Panel Review: Pricing, Specs, Pros & Cons

Mission Solar Panel Review: Pricing, Specs, Pros & Cons

Mission Solar Panel Review: Quick Summary

Mission Solar produces high-efficiency solar panels out of San Antonio, TX. While there are more cost-effective imported panels on the market, Mission’s panels are extremely competitive with other American-made options at 68-71 cents per watt. Read on for more pros & cons and pricing info.

Looking to go solar and support American goods in the process? Texas-based Mission Solar is our preferred manufacturer of American-made solar panels.

Mission’s panels are among the most efficient on the market, and their pricing is competitive given the higher costs associated with American manufacturing.

However, if you don’t mind buying imported panels, there are plenty of less expensive options available (with the trade-off that imported panels tend to be less efficient as well).

In this review, we’ll cover pricing, specs and pros & cons of Mission Solar panels. We’ll also compare their product line against some alternative options to help you find the best fit for your project.

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Mission Solar Panels: Pricing & Specs

  • Price: $219 (as of 4/24/19)
  • Wattage: 310W
  • Cost Per Watt: 71 cents/watt
  • Efficiency: 18.65%
  • Warranty: 25 years
  • Price: $225 (as of 4/24/19)
  • Wattage: 315W
  • Cost Per Watt: 71 cents/watt
  • Efficiency: 18.95%
  • Warranty: 25 years
  • Price: $255 (as of 4/24/19)
  • Wattage: 375W
  • Cost Per Watt: 68 cents/watt
  • Efficiency: 18.89%
  • Warranty: 25 years

Pros of Mission Solar Panels


Mission Solar is a “born and bred” American company. They were founded in San Antonio, TX, where they employ hundreds of people at their manufacturing plant.

This is a big sticking point for our customers. Locally produced panels cost 15-25% more than imported panels due to stricter manufacturing regulations and labor laws in America. But many prefer to pay that premium to support domestic job creation efforts and stimulate the local economy.

Mission Solar is our preferred all-American panel manufacturer, producing high-efficiency panels at a competitive price point.

High Efficiency

An array of black-on-black Mission Solar panels.

Mission Solar panels have higher efficiency than most other panels on the market, which translates to more power from a smaller array size.

Residential solar panels come in standardized sizes of 60 or 72 cells, but not all panels are created equal. 60-cell panels typically range from 275W to 325W, while 72-cell panels fall between 330W and 380W.

Mission Solar’s 315W 60-cell panels and 375W 72-cell panels land on the high end of these ranges.

More efficient panels mean you need to buy fewer overall panels to reach your target system size. For example, the production from this 24-panel Astronergy system and this 20-panel Mission Solar system are almost identical, but the Mission Solar system takes 4 fewer panels to achieve the same output.

That can be a game changer if you have limited build space for your array. Of the two systems linked above, the Mission Solar array will save about 72 square feet of space on your property.

High-efficiency Mission Solar panels allow you to get more output from a limited build space.

It’s worth noting that there are some super high-efficiency panels from the likes of LG and Panasonic, but the cost-per-watt is prohibitively high. LG’s 360W 60-cell panel ($1.33/watt) is almost twice as expensive as Mission’s 315W 60-cell panel ($0.71/watt). LG’s panels are extremely efficient, but you’ll see diminishing returns investing in cutting-edge technology.

PERC Cell Technology

Mission Solar’s panels use PERC (Passivated Emitter and Rear Cell) technology, which is more efficient than regular mono- and poly-crystalline cells that have traditionally been used in most panels.

In (relatively) simple terms, PERC cells add a layer on the bottom of the cell to reflect sunlight back through the Silicon layer, giving it a second opportunity to generate electrical current. It essentially exposes the panel to more sunlight, which leads to a bump in efficiency.

In addition to higher efficiency, PERC cells also perform better in low light and high temperatures. This article explains more about the benefits of PERC technology.

Cons of Mission Solar Panels

Higher Cost-Per-Watt

Mission Solar’s panels aren’t the cheapest option on the market. At 71 cents per watt, Mission’s place in the market is a nice mid-range option that is priced competitively against other American-made panels.

But if your primary goal is getting the most out of your budget, imported solar panels tend to be a better value.

Jinko Solar (51 cents/watt) and Astronergy (54 cents/watt) are the most cost-effective panels we offer right now. Both options are about 25% cheaper than Mission Solar 315W panels.

Provided you have enough space to use the lower-wattage panels, Jinko and Astronergy will give you more output per dollar spent on your system.

Mission Solar Panels: The Verdict

Mission Solar is our preferred manufacturer of American-made solar panels. They employ the latest cell technology to offer high-performance panels that strike a balance between efficiency and price.

They’ll never be as cost-effective as imported panels, which are cheaper to manufacture due to regulations and labor laws. If you want to make the most of your budget, you will be better served with Jinko Solar or Astronergy panels. But if you prefer to support American-made goods, Mission Solar panels are the most appealing option on the market.

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Astronergy Solar Panel Review: Pros & Cons, Price & Specs (2019 Update)

Astronergy Solar Panel Review: Pros & Cons, Price & Specs (2019 Update)

Review: Astronergy 280W Solar Panels

Astronergy’s solar panels are among the most cost-effective on the market. In this review, we’ll cover pros & cons, pricing and specs of Astronergy’s 280W panel, as well as pick out some alternatives for those who prefer higher-efficiency, locally made options.

Astronergy’s 280W solar panels offer the best value on the market right now. If maximizing your budget is your primary goal, Astronergy’s pricing is among the most competitive of all Tier 1 solar panel manufacturers.

In this article, we’ll review the Astronergy 280W solar panel and go over its ideal use case. We’ll also cover some alternatives in case you prefer locally-made products, or need panels that are a little more efficient.

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Astronergy 280W Panel – Price & Specs

Let’s start with a quick breakdown of some key specs for Astronergy’s 280-watt offering:

  • Price: $150 (as of 4/15/19)
  • Wattage: 280W
  • Cost Per Watt: 54 cents/watt
  • Efficiency: 17.2%
  • Warranty: 25 years, backed by third party

Astronergy Solar Panels: The Pros


The main appeal of Astronergy panels is their low cost-per-watt. If you have plenty of space to build your system, Astronergy’s 280W panels are the most cost-effective option on the market. At 54 cents per watt, you won’t find a better value from any other Tier 1 manufacturer.

(“Tier 1” refers to a list published by Bloomberg that ranks solar panel manufacturers by financial stability, longevity and production volume. Companies on this list are mainstays of the solar industry.)

Astronergy 280W panels use polycrystalline cells, which are not the most efficient option available. For example, our Mission Solar 315W panel packs an extra 35 watts of production into the same frame size, which comes down to more efficient cell technology.

But higher efficiency often equates to higher cost-per-watt. While Astronergy’s panels are less efficient, they represent the best value around. Your array will take up more space, but the tradeoff is higher overall output per dollar spent.

Reinsured Warranty

Tier 1 solar panels are warrantied for 25 years. A lot can change in that time, and unfortunately, we’ve seen our fair share of solar panel manufacturers come and go due to the competitive nature of the manufacturing market.

When a manufacturer folds, customers can get stuck holding a useless warranty, because there’s no way to file a claim once the company goes bankrupt.

Astronergy offers protection against that scenario with a third-party backed warranty. Should Astronergy ever go out of business, the warranty is backed by a third-party reinsurance company called Munich RE.

Astronergy is also a part of the Chint Group, one of the largest electronics manufacturers in China. They were ranked the 4th largest company in China by Forbes in 2013. Their size and staying power offers an extra layer of protection for the warranty.

That kind of third-party backing is a nice bit of assurance that your system will be covered for the long haul.

Astronergy Solar Panels: The Cons

Overseas Manufacturing

Astronergy is headquartered in China, with manufacturing plants in a variety of countries overseas. This is a drawback for our customers who prefer to invest in American-made products.

Locally-made panels cost a bit more than imported products due to higher wages and stricter manufacturing standards. But for many people, the extra costs are a fair tradeoff to stimulate the local economy and support job creation in the US.

If you’d prefer to buy American-made goods, we’d point you toward the Mission Solar line, which are assembled in San Antonio, TX. At 71 cents per watt, you’ll pay a 25-30% premium to support American-made products.

The upside of the Mission Solar panels is that they come with higher wattage than Astronergy panels, making them a bit more efficient (which leads to our next point).

Low Efficiency

Most solar panels for residential use come in two standardized sizes: 60-cell and 72-cell. But these panels come in varying wattages, depending on the manufacturing process and the efficiency of the cell technology in use.

For example, Astronergy 280W panels are the same size as Mission Solar’s 315W panels. Both are 60 cells, but the Missions employ more efficient cell technology.

Higher efficiency panels take up less space on your property, because you need to buy fewer panels to hit your energy production target. Astronergy’s 280W panels are on the low end of this efficiency scale, so make sure you have plenty of room to build.

There are also super high-efficiency panels from the likes of LG, but they tend to have a prohibitively high cost-per-watt compared to other options using more established technology. The table below shows the trade-off between panel efficiency and cost-per-watt.

Ideal Application For Astronergy Solar Panels

Astronergy solar panels are best suited for residential applications without any space limitations.

If you have plenty of room to build your system, there’s no real downside to choosing less efficient panels. Your array may take up 10-20% more space, but you will enjoy more production at a lower overall cost.

We would not recommend the Astronergy 280W panels for commercial installs. Commercial systems rarely offset 100% of a property’s energy needs, so the goal is often to squeeze as much production as possible out of the available space.

These builds are more concerned with maximizing wattage per square foot than sticking to the least expensive option. They also tend to use 72-cell modules because there are fewer components to install and maintain.

Residential roof mount systems have similar restrictions. Compare the production of this 24-panel Astronergy system to this 20-panel Mission Solar system. The output is almost identical, but the Mission Solar array will take up roughly 71 square feet less space, which can often determine whether or not the array will fit on your roof.

In short: Astronergy makes the most cost-effective panels, but you need a bit more room to make them fit on your property.

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Do Solar Panels Work in Winter? Your Guide To Snow & Solar Panels

Do Solar Panels Work in Winter? Your Guide To Snow & Solar Panels

Do Solar Panels Work in Winter?

  • Panels must be exposed to light to produce. Keep snow clear from the face of your panels.
  • Colder temperatures increase voltage, which means your system is more efficient when it’s cold & sunny.
  • However, there are fewer sun hours during the day in the winter, leading to an overall drop in production.
  • Take steps to conserve energy to get the most out of your system in the winter.

Wondering if you can still go solar in cold climates? Good news: snow and solar panels are not mutually exclusive.

This is a question we commonly hear from people who live in colder climates that get heavy snow in the winter. Do solar panels work in winter? Does heavy snow on solar panels affect their output?

It’s a reasonable question since solar panels capture their energy from the sun, and there’s less sunlight to go around in the winter…

But the answer to this question is fairly simple: yes, solar panels work in the winter. You just have to take precautions not to let snow build up on the panels.

It’s true that there are fewer sun hours in the day during winter, which means a shorter window for production.

But that drawback is somewhat offset by the fact that your system gets more efficient in the winter. As temperatures fall, panel voltage increases, which leads to higher production in colder temperatures. If it’s cold and sunny, your system works at extremely high efficiency.

If snow builds up on panels and blocks light from reaching the cells, that will prevent those cells from producing. But the easy fix is to simply remove snow from the panels.

All things considered, we estimate your system’s production will drop around 15-45% below its average output in the dead of winter. The production gap gets wider the further you are from the Equator. Plug your ZIP code into the PVWatts calculator to get monthly production estimates for your location.

With that in mind, here are a few quick tips to get the most out of your solar panels in the winter months.

Pole Mounts Help With Snow Removal

We recommend fixed roof or ground mounts for most standard solar builds because they are the most cost-effective solutions.

However, if heavy snow is a concern in your area, you might want to look at a pole mount for your panels.

Recommended product: General Specialties Pole Mount

A pole mount is exactly what it sounds like: a tall pole that you can mount your panels on. They’re designed to allow you to adjust the tilt of your panels as you see fit.

Pole mounts accomplish two important things.

The first benefit of pole mounts is that they lift your array higher off the ground. When it snows, there’s room under your array for the snow bank to build up without obstructing the panels. With a fixed ground mount setup, the bottom of your array could potentially get buried in snow buildup.

The second benefit is that pole mounts are usually set at a steeper tilt angle. If enough snow builds up on the panels, gravity takes over and the snow slides off under its own weight. You may get temporary buildup, but pole mounts are designed to shed snow and keep your panels clear.

Pole mounts are a great option for snowy climates, but they do cost a bit more than fixed mounts. It’s not necessary to buy a pole mount for your array, especially if you don’t mind doing a bit of maintenance during the winter.

Maintenance Tips For Getting the Most Out Of Your Solar Panels in the Winter

1. Clear snow off your panels

If you don’t have a pole mount (or even if you do), it’s wise to brush excess snow off your panels so that it doesn’t block the solar cells and limit production.

If possible, opt for a broom or brush with soft bristles. The face of your panels is made out of glass. They’re going to be fairly sturdy, but you don’t want to use abrasive materials that could scratch the glass.

Be careful climbing on to your roof to clean your panels if you have a roof-mounted system. The ice buildup combined with the slope of the roof presents hazardous conditions. If you attempt to clear snow off your roof-mounted array, please take the necessary safety precautions, like wearing heavy-grip shoes and a secure harness.

If you live in an area where it snows regularly, we strongly recommend opting for a ground mount system. They are much more accessible and safer to maintain because you don’t have to climb on your roof to access your panels.

2. If Possible, Adjust Your Array’s Tilt Angle

Solar panels produce the most energy when they face directly into the sun. The position of the sun in the sky changes throughout the year, and it takes a much lower path during winter months.

Fixed mounts can’t be adjusted, but if you opt for a pole mount, you can adjust to a more optimal angle during the winter.

Read our article on finding the optimal solar panel tilt angle for advice on setting your panels in the right position to get the most production out of them.

3. Take Steps to Conserve Energy

Less daylight means less solar production, so it helps to reduce energy consumption in your home to account for this. Some quick tips:

Turn off lights and other appliances when not in use.

Replace high-wattage light bulbs with energy-efficient ones. You can go from 60W to 15W bulbs and save 75% of consumption.

Unplug appliances from your wall if possible. Plugged-in appliances still draw a small amount of power even when they are not turned on. These are called “ghost loads.” TVs, laptops, phone chargers, microwaves, stereos, and so on—these can all be unplugged to save energy when not in use.

Consider adding more insulation and sealing leaks around your doors/windows to retain more heat in your home. You can also insulate your water heater to retain heat.

Set the thermostat to a cooler temperature and use blankets and/or layers to keep warm. A smart thermostat can help you schedule temperature changes to keep your home cooler while you’re out and warm it up by the time you come home.

These are just a few ideas. Check out our article on lowering energy use and conserving energy for more tips!

Battery Maintenance Tips For Off-Grid Systems

If you live off the grid, properly maintaining your battery bank is crucial to keeping the lights on.

Extreme cold temperatures can be very hard on your deep cycle batteries, so it’s important to take care of them properly.

Make sure your batteries are installed indoors. If they are outdoors, make sure that the compartment is properly insulated.

Lead-acid batteries freeze at below-zero temperatures, which will permanently destroy them. Lithium-ion batteries have a specific temperature operating range and often can’t be operated at extremely cold temperatures.

Always keep diagnostic tools at your disposal. This includes a digital multimeter and a handheld battery refractometer.

If continuous power supply is crucial, make sure that you have a backup generator ready and tested for functionality in advance. Generators must be regularly exercised to keep them tuned up and functioning properly.

In the winter, the exercise cycle needs to be longer to melt any snow or ice that has blown into the engine. For example, the Kohler generators we sell need be exercised weekly for 20 minutes in the summer and 30 minutes in the winter.

Recommended Product: Kohler 14kW Generator

For flooded lead-acid battery banks, keep a stock of distilled water for your batteries. The battery electrolyte level should be checked regularly. Check the battery manual to determine the appropriate fill level. Add distilled water to keep the fluid levels where they need to be.

Battery capacity is impacted by cold temperatures, because the chemical reaction inside the batteries slows down. Lead acid batteries are going to lose a significant amount of their capacity as temperatures drop.

Flooded lead-acid batteries should receive an equalize battery charge from a high capacity battery charger about once every 3-4 months to keep the plates free of sulfate buildup.

Most batteries do not fail instantaneously, but degrade over time. That degradation is accelerated if you don’t take proper care of your battery bank. Set a regular battery maintenance schedule and adhere to it diligently to ensure they work properly throughout the winter.

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Best Portable Solar Panels For RVs, Boats & Mobile Use (2019 Edition)

Best Portable Solar Panels For RVs, Boats & Mobile Use (2019 Edition)

Best Portable Solar Panels For RVs, Boats and Mobile Use

  • Solarland’s portable solar panels are ideal for RVs since they are warrantied for vibration.
  • Sunpower’s lightweight, flexible solar panels are great for camping.
  • Mission Solar makes the best solar panels for boats—they are rated to protect against corrosion from salt mist.

A big part of the appeal of going solar is the ability to generate electricity in places without access to power lines. This is especially important if you live your life on the road in an RV, boat, conversion van or tiny home.

Portable solar panels are often less cumbersome and easier to use than generators, which can be heavy, noisy, dirty, and need to be refueled regularly. Solar is often the most convenient solution for people who live in RVs, boats or tiny homes (or love to take road trips / travel frequently).

I’ve been in the solar industry since 1998 and have designed hundreds of mobile-ready solar electric systems in that time. More people seem to be taking to the mobile lifestyle lately, so I wanted to put together my assessment of the best portable solar panels for RVs, campers, boats and tiny homes.

If you’re building a system that needs to withstand the elements and survive life on the move, this guide is for you.

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What to consider when picking solar panels for mobile use


First things first: there’s really no reason you can’t use traditional solar panels for mobile use.

By “traditional,” I mean the full-sized panels you would install on the roof of a typical home or office. These are the most cost-effective option, and l would still recommend looking into them so long as you have the space to mount them.

The snag is that these panels are quite large: about 3.5 feet wide and 5.5 to 6.5 feet tall (depending on whether you choose 60-cell or 72-cell panels). These work great for tiny homes, but they don’t really fit on the top of a van, for example.

They also may not be warranted for use in a mobile application. Specifically, the warranty would not protect against damage from vibration, which could occur if you drive with panels mounted to your roof.

And let’s say you go camping and want to haul your system from the parking lot to leave it by your tent. Traditional full-sized panels are going to be a huge burden to lug around. I would strongly recommend opting for smaller, more portable solar panels in these cases.

Mounting Options

Panels should be built to handle high wind load, since you will likely be moving down the highway at high speeds.

Be sure to consider the space and structure available for mounting panels. Solarland offers a range of mounting brackets for this type of application, including simple Z-brackets for bolting a panel onto a flat surface, and specialty marine mounts that are designed for boats.

Marine Applications

Marine systems should be built in a dry space. Ideally, your panels should be mounted as far away from the water as possible.

Your battery bank enclosure needs to be built in a dry space. Enclosures aren’t water-tight (since the batteries need to be ventilated), so you should place it somewhere that will protect water from coming in contact with the electronic equipment.

If you plan to take your boat out in saltwater, look for panels that are IEC 61701 certified to prevent corrosion from salt mist.

Mobile-Ready Inverters & Power Centers

It is also crucial that the rest of your system components are mobile-ready. A major component is picking an inverter that is built for mobile use.

The key feature of mobile-ready inverters is neutral ground switching capability. This means that the inverter can plug into shore power and automatically switch so it is safely grounded.

This safety feature keeps your system grounded while on the road. But it can also remain properly grounded when you plug in your RV at a campsite, for example.

Magnum, Cotek and Outback sell inverters that are tailored for mobile use. We also sell pre-wired power centers that are configured in-house for use in mobile and marine applications:

3. Best Portable Solar Panels For RVs / Campers / Mobile Homes

Some RV customers like to use our large solar panels. This way they have a high voltage and high wattage output in a single panel. This is also the most cost-effective solution.

Standard solar panels with a traditional aluminum frame come in many sizes, ranging from 20 watts up to 360 watts. These gain wattage every year, and I would not be surprised to see a 375-watt solar panel by the end of 2019.

However, remember that these panels are usually not warrantied for protection against vibration, which might occur if you are driving down the highway at high speeds.

Instead, look to something like the Solarland 12V and 24V panels, which have a robust frame and are warrantied for mobile applications.

If you don’t need a large solar array, you might enjoy our flexible solar panels. We recommend the SunPower 50W and 100W flexible panels. These are very lightweight, and designed to be stored while driving and deployed once you arrive at your campsite.

I keep mine paired with a 50’ cable so that I can move it around the campsite and get it into the sun, while keeping my camper in the shade. These also fit nicely across my windshield, so I can collect solar energy while blocking the sun from heating up my camper.

My trusty SunPower 100W flexible solar panel in the windshield of my camper.

The flexible solar panels are limited to about 100 watts, so they are intended for portable and smaller uses. They have grommets in the corners so that you can quickly secure them using bungee cords or other appropriate tie downs.

Best Portable Solar Panels For Your Boat

Boats are more likely to use the larger framed type panels, as they have plenty of room to mount them. You can see this concept in action on the River Otter Waterway Cleanup Project (featured below), a marine system we designed for a client which utilizes full-sized panels.

Many of my customers that just boat around for a few hours a day like the flexible panels. They are just smaller, more portable, and get the small jobs taken care of with a lighter solar panel.

If you are going to be boating in salt water, you will want to choose a solar panel that is rated for salt air and corrosive environments.

We currently offer Mission Solar for these applications as their panels pass the IEC 61701 certification for protection against corrosion from salt mist.

When building a solar array on a boat, your choice of accessories matters more than the panels you choose.

This will primarily come into play when you are installing your power center—the enclosure that contains your charge controller, inverter and other necessary components.

These power centers need to be ventilated properly, meaning they aren’t water-resistant. They should be built in a place where they will remain dry at all times.

Hit the Road With Confidence

This should give you plenty to think about as you plan your mobile solar system. When you’re ready to finalize the design, give us a call at 1-800-472-1142 or request a consultation online.

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What are the Best Solar Panels? (Updated For 2019)

What are the Best Solar Panels? (Updated For 2019)

What are the best solar panels on the market in 2019?

How do you find the best solar panels for your system?

It’s not an exact science. “Best” will mean different things to different people.

You may care about efficiency and long lifespan. You might want to support American-made goods.

Or maybe you just want the most cost-effective option.

We’re going to put our two decades of system design experience to good use to bring you handpicked recommendations of the best solar panels on the market in 2019. And if you prefer your info in video form, we put one of those together too:

Before we go over our methodology, here’s a sneak peek at our picks. (Let’s be honest, you’re here for product recommendations, so we won’t make you scroll too far.)

Best Budget Panels:

Best American Panels:

Best Premium Panels:

Best RV/mobile Panels:

Best Panels for Remote Applications:

Best Panels for Industrial Use:

How to Pick the Best Solar Panels for Your Project

There are a handful of factors that influence how good panels are. Here are the main things you should look at when you research solar panels.

Cost per watt

For most people, budget is the primary factor influencing decisions during the design process.

Panels come in all different sizes. Full-sized panels typically fall in the range of 275-400 watts, though there are also smaller panels for specialty off-grid applications.

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The great equalizer is cost-per-watt. Divide the panel price by how many watts it outputs. You’ll get a “true” pricing number, which you can use to compare all panels on a level playing field.


There are two different warranty categories – performance and workmanship.

The performance warranty guarantees your panels will work above their rated efficiency for the duration of the warranty. Most manufacturers promise their panels will work at or above 80% efficiency after 25 years.

25 years is the industry standard, but a few manufacturers offer longer performance warranties of 30 years.

Then there’s the workmanship warranty. This protects against manufacturing defects and other physical problems with your panels.

The workmanship warranty is shorter than the performance warranty. A generous workmanship warranty gives a great indication that the manufacturer knows they are putting out a reliable product.

The industry standard workmanship warranty is 10 years, with some companies offering 20-year guarantees.


A solar panel’s efficiency rating refers to the amount of sunlight the panel can convert into usable energy. 14-22% is an acceptable efficiency range for panels produced by major manufacturers.

This relates directly to the output of a solar panel (in watts). For example, a SolarWorld 290W panel is 17.3% efficient, while their 300W module is 17.89% efficient.

Temperature Coefficient

Solar panels are tested in ideal conditions. When manufacturers measure panel output, they perform tests inside a climate-controlled factory.

Obviously, the real world is going to introduce less-than-ideal conditions. During those sweltering days in the dead of the California summer, your system will lag behind its rated efficiency.

The impact temperature has on true panel output is the temperature coefficient. The coefficient measures how much efficiency is lost for each degree above or below ideal test conditions.

We’ll give an example in Celsius, because that’s what most manufacturers measure: energy loss per 1°C temperature change.

For example, let’s say a panel was tested at 45° C, but its current temperature is 55° C. If the temperature coefficient is 0.4% Wp (Watt power), you can multiply that by the difference in temperature (10° C). That panel is operating 4% below its rated efficiency on that particular day.

There are separate temperature coefficients for voltage, amperage, and wattage. Certain types of solar panels like monocrystalline can perform slightly better at higher temperatures.

The temperature coefficient usually isn’t the most important variable to focus on unless you are in an area that gets extremely hot. This is because heat reduces the efficiency of your solar panels, making them operate at a reduced output.

Company History

The longevity and reputation of the panel manufacturer play a part in our recommendations. What good is a warranty if the company goes out of business before they get a chance to honor it?

For that reason, we look at companies with a stable track record in the solar industry. Every product on this list is produced by a major manufacturer that we don’t expect to disappear any time soon.

UL Listed

Underwriters Laboratories is an organization that has been around for over 100 years. UL sets standards and performs safety tests to ensure products are safe for public use.

Solar panels must be certified to UL 1703 standards if they are being installed on your home.

What are the best solar panels on the market in 2019?

Without further ado, here are the best solar panels you can buy in 2019 for a variety of applications. The info in this article is current as of 9/20/2019.

Best Value Solar Panels: Astronergy 345W

  • Cost: $225 (65 cents per watt)
  • Workmanship warranty: 10 years
  • Performance warranty: 25 years
  • Efficiency: 17.7%
  • Degradation: -0.7% / year
  • Temperature coefficient: -0.376% Wp
  • # of cells: 60
  • Cell type: Poly

Looking for panels that won’t break the bank? Astronergy makes the best solar panels you can get from a pure value perspective.

Of the major module producers, Astronergy has the lowest cost-per-watt panels we’ve found. Their 345W panel retails at $225 (at the time of publication), which shakes out to 65 cents per watt.

A few of our employees run their home systems on Astronergy panels, and we also picked them for the system that powers the Wholesale Solar flagship office.

Their 17.7% efficiency is very respectable at this price point, and the warranty is on par with industry standards.

Astronergy also sets their warranty program apart from other companies by offering third-party insurance. Should they ever go out of business, the warranty would still be valid from the third-party provider.

That’s more for peace of mind than anything. Astronergy is a part of one of China’s largest electronics manufacturers. We expect them to be around for a long time to come.

But the extra bit of insurance on the warranty coupled with the low price point makes these panels a popular choice.

Best American-Made Solar Panels: Mission Solar 375W

  • Cost: $275 (73 cents per watt)
  • Workmanship warranty: 10 years
  • Performance warranty: 25 years
  • Efficiency: 18.89%
  • Degradation: -0.7% / year
  • Temperature coefficient: -0.375% Wp
  • # of cells: 72
  • Cell type: Mono

Among the American solar panel manufacturers, Mission Solar is our top pick. They design and assemble high-efficiency panels in San Antonio, Texas.

With solar panels getting cheaper all the time, the price gap between imported and American panels has shrunk considerably. Imported 345W Astronergy panels now sell for 65 cents per watt, while American-based Mission Solar sells 375W panels at 73 cents per watt.

Compare that to the premium LG panels featured in the next section, which go for $1.38 per watt.

Looking at the price distribution, Mission Solar’s place in the market is clear. Their prices are competitive with imported panels, and they also give the high-efficiency models a run for their money on output (while blowing them out of the water on the price tag).

If you want to pick up some high-efficiency panels at a competitive price (and support American goods in the process), Mission Solar is the go-to choice. We recommend both their 315W (60-cell) and 375W (72-cell) panel.

Best Premium Solar Panels: LG 360W

  • Cost: $495 ($1.38 per watt)
  • Workmanship warranty: 25 years
  • Performance warranty: 87% efficiency after 25 years
  • Efficiency: 20.8%
  • Degradation: -0.4% / year
  • Temperature coefficient: -0.3% Wp
  • # of cells: 60
  • Cell type: Mono

LG doesn’t just make solar equipment; they’re one of the leading electronics manufacturers in the world.

We feature LG’s 360W panel in our premium packaged systems. They are super space-efficient, packing more output into a 60-cell panel than most 72-cell panels on the market are capable of producing.

Every solar project is different, and some people have the challenge of building a system in a compact space. For example, you may only have room for 10 panels on your roof. These LG panels will help you squeeze as much output as possible out of the limited space available to you.

They also have a long lifespan. At -0.4%/year, the degradation rate of these panels is 0.3% better than our featured Astronergy 335W panel.

That may not sound like a lot, but when you work the math out, it means LG panels will retain 7.5% more efficiency than Astronergy panels at the 25-year mark.

And LG’s solar panel warranties are a thing of beauty.

Where most companies aim for a 10-year workmanship warranty, LG covers the full 25 years.

On the performance warranty side, LG ensures their panels will still be 87% efficient after 25 years. That’s a stronger promise than the standard 80% after 25 years.

What are the best solar panels for off-grid systems?

We get this question a lot: is there any difference between panels for off-grid and grid-tie properties?

There is a bit of nuance to the answer.

The panels themselves can always work regardless of system type. There is no such thing as “off-grid panels” or “grid-tied panels” specifically.

However, panels must be paired with other components and sized accurately, especially in off-grid systems.

Historically, off-grid systems have used PWM charge controllers, which required that you match 12V solar panels with a 12V battery bank.

Now, most modern off-grid homes will use an MPPT charge controller, which can adjust the incoming PV voltage to work with almost any solar panel.

However, there are still string sizing considerations based on the panel and charge controller specs. All of the components must be supplied with the appropriate voltage and current. Batteries add another layer of complexity for off-grid systems, since the array must be sized to sufficiently recharge the batteries without overcharging them.

There are also a handful of panels that are designed specifically for off-grid applications:

Best Solar Panels for RVs / Mobile Applications

Solar is also a great solution for mobile applications like RVs and boats. But you’ll need smaller panels to work around any space constraints.

The solution for this is SunPower 50W and SunPower 100W flexible panels.

The lower profile helps you find the right configuration with limited space available. And since these panels can bend up to 30 degrees, they can flex around curved surfaces to make the most of the space you have.

These panels are lightweight, easy to install and perform well in low light. They’re built to adapt to rough and changing conditions that come with living life on the road.

At just over $2.50 per watt, they’re more expensive than traditional panels (even the premium LG panels). But it’s a fair tradeoff for a mobile-ready solar panel solution built to perform in harsh conditions.

Best Solar Panels for Small-Scale Industrial / Remote Applications

The last category we’ll look at is the best solar panels for small-scale remote applications.

These tend to be used to power remote equipment for a variety of industries:

  • Lighting
  • Telecommunication
  • Security & surveillance
  • Oil & gas
  • Water pumping
  • Traffic
  • Utility monitoring

A lot of times this equipment is in a remote location (like at the top of a mountain or floating on a buoy in the middle of a lake) and you need a small, self-contained system to keep it running.

We would recommend both Solarland and Ameresco, depending on the application. A few examples:

This represents the high end of the output range for 12-volt panels. Both companies offer a variety of 12V panel options ranging from 1W to 160W. Solarland also has 24V options, including one that goes up to 190W.

For certain industrial applications, you may need panels that are certified for use in hazardous locations. The SolarLand C1D2 (Class 1, Division 2) panels are your go-to choice.

There are 12V options at 45W, 60W and 150W, as well as a 140W panel that produces 24V:

These can also be used on RVs and boats, where you just want a solid panel with glass and an aluminum frame. If you don’t need the flexibility of the Sunpower panels, these are actually cheaper by about 25-50 cents/watt depending on panel size.

That’s it for our recommendations! We think these are the best solar panels you can get for your money in 2019, but prices and product configurations will change rapidly as technology improves.

As you do your research, seek out efficient panels from trusted manufacturers, and calculate the cost-per-watt so you can compare products on a level playing field.

If you follow these guidelines, you’re sure to find the right solar panels to power your system.

This article was updated on 9/20/2019. For our most current prices, take a look at the solar panels page in our shop.

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Why Are Solar Panels So Expensive?

Why Are Solar Panels So Expensive?

Why Are Solar Panels So Expensive?

Large solar installers mark up their quotes to 2-3x the cost of equipment, turning a $10,000 system into a $30,000 project. You can save money by hiring a local contractor for much less (or even installing it yourself), turning your system into a sound long-term investment.

Over the long term, solar energy is the cheapest way to power your property. But it requires a significant up-front investment that slowly pays back over time.

Everyone loves the idea of saving money on energy bills. But when someone puts a quote in your hands for a system that costs more than a new car, you might start to have your doubts…

“Seriously, why are solar panels so expensive?”

We get this question all the time. Here’s our explanation:

1. Huge Markup on Turnkey Installations

Did you get a quote from a full-service solar company that installs their own equipment? If so, they’re probably marking up installation costs like crazy – as much as double the cost of materials. You can save a good chunk of money by installing it yourself or hiring an independent contractor for less.

2. 30% Federal Tax Credit

You get a 30% federal tax credit for going solar. Just know that whatever you pay, you’ll deduct 30% of the cost of your system and installation from your taxes. (Heads up; the tax credit is being phased out by 2022.)

3. Solar is an Investment

The initial cost of solar is high, but the money you save on electric bills pays for the system over time. The amount of time it takes you to break even is known as the payback period.

This is a significant concept for anyone trying to understand why solar is a smart investment. Watch this video to learn how to calculate payback period on your system:

4. It’s Fine to Start Small

You can always start small and cover part of your energy needs, then expand as your budget allows.

It’s hard to give a conclusive answer, since this is such an open-ended question. But we hear it most often from people who have quotes out with a turnkey installer.

A system that costs about $10,000 in materials, like this 6.6kW grid-tied system, might be marked up to $30,000 after installation costs from a turnkey provider.

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Which explains why sticker shock is a common phenomenon in this industry.

So here’s our advice: the best way to save money on solar is to install it yourself, or hire an independent contractor to complete the installation at a fraction of what a turnkey provider would charge you.

If the up-front cost is still a concern, the next solution would be to scale back to a more modest system design and then expand on it as your budget allows.

Don’t Overpay for Installation

Most of the time when someone asks us why solar panels cost so much, they’re working from a quote from a turnkey installer (a company that offers an all-in-one solution to source the equipment and perform the installation).

Here’s the trick: the cost of equipment is pretty much the same wherever you go. The markup is in the installation.

Large installers have overhead costs. They have to cover labor, pay rent on their office, maintain a fleet of service vehicles, supply equipment, take out insurance, and so on…

All those operating costs get rolled into the charge of installation.

And the markup is obscene.

A typical installation might take a team of 3 laborers a full 8-hour day to complete. At $25/hr, that’s $600 in total labor costs. Add a bit more for tools and overhead, and the installer might spend about $1000 to send a crew to complete the job.

And yet…turnkey installers charge 1-2 times the cost of equipment to install it. If your equipment costs $10k, your final bill may come out to $20-30k once everything is bundled together.

Uh huh. You can see why we’re such strong advocates for DIY solar.

If you’re holding a quote from a turnkey installer, we strongly recommend you explore DIY as an option. Installing a solar system can seem scary, but it’s a lot easier than it looks.

We’ve helped thousands of people through the DIY installation process – take a look at the customer galleries in our Install of the Month feature for inspiration.

Don’t feel comfortable installing your own solar system? There’s a nice middle ground between DIY and turnkey: buy the system direct, then hire an independent contractor to install it.

Independent contractors tend to charge way less for installation. They should charge you 75 cents to a dollar per watt, which means you’d pay $5-6k to install the same system we used as an example above. You can see the value comparison of all three options in the chart below.

This is not to say that we fault turnkey installers for what they do. If you have a family or a demanding job, time is likely your most valuable resource. A turnkey solution is absolutely worth it if you can afford it and don’t have time to design your system yourself.

Just know you’re paying a premium for them to install the system, and that premium is awfully steep.

30% Federal Tax Credit Makes Solar More Affordable

If you live in the United States and choose to go solar, your system is eligible for a federal tax credit.

Today, that credit is 30% of your cost to go solar (which includes the cost of installation and equipment). However, it will shrink over time to 26% in 2020 and 22% in 2021, disappearing completely by 2022.

The tax credit is a reduction of the income tax you owe. For example, if you owe $3,000 in taxes but received a $3,000 tax credit on a $10,000 system, your tax liability would be $0.

If solar seems too expensive, keep in mind that 30% of your system cost will be refunded when tax season comes. However, that benefit will be phased out over the next few years. So if you want to claim the extra kickback on your taxes, you’ll have to do so sooner rather than later.

Read more: The Federal Solar Tax Credit, Explained in Plain English

Understanding Payback Period

Even if you skip the installer, you’ll still spend a good amount of money on the system itself. That number can be a little bit scary without any context.

It’s important to think of solar as an investment with a payback period.

Solar saves you money in the long run by reducing or eliminating electric bills. Over time, the money you save on electricity adds up.

Your payback period is the amount of time it takes for your energy savings to pay off the up-front cost of the system. (Other factors, like tax incentives, also speed up your payback period.)

The formula for payback period is:

System Price ÷ Value of Electricity ÷ Annual Usage = Payback period (years)

(This is a simplified formula. It doesn’t take into account certain factors like energy cost inflation, which increases costs by about 3% per year, or the scheduled replacement of smaller parts, like the inverter.)

The system may be pricey up front, but it will provide more than enough energy to pay for itself. For example, panels are warrantied for 25 years, but our sample 6.6kW system may pay for itself after about 8 years of typical use. The final 17 years of ownership yields profit off your investment.

Learn more about how to calculate payback period and return on investment for your solar system.

Start Small To Trim The Cost Of Solar

You don’t have to offset 100% of your energy costs if your budget doesn’t allow for it. It’s always possible to start with a modest system and then expand later.

You can start as small as one solar panel and a single micro-inverter. Solar panels and micro-inverters are a 1-to-1 system, meaning each panel is connected to its own micro-inverter.

See it: Enphase IQ7+ micro-inverters

This configuration can be expanded indefinitely. We build modest systems like this all the time for people who want to offset a small portion of their energy, then add to it over time as budget allows.

If you want to take this approach, be sure to mention your expansion plans to your system designer / sales tech. Not all inverters and panels are compatible. Start with a long-term plan in mind and plan appropriately.


Solar can be expensive in the short term, but the incentives will save you plenty of money over the life of the warranty. And the return on investment improves dramatically if you skip the turnkey provider and install it yourself – or at least hire an independent contractor to do it for you.

Trying to figure out whether solar is right for you? Take a look at our guide to getting started with solar. It’s tailored for people who are just starting to research the solar energy landscape.

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Solar Panel’s Cooling Effect

Solar Panel’s Cooling Effect

San Diego, CA-  The benefits of installing  solar panels on your home go far beyond the electricity produced. According to new research by the University of California at San Diego, the shade provided by a solar panel array will actually insulate your home from heat to the point of lowering cooling costs. It is estimated that these savings will result in a 5% discount on the price of the system over its lifetime.

The Jacobs school of engineering’s research team used thermal imaging cameras to analyze the difference in heat signatures coming from roofs with and without a solar array. On average, a building’s ceiling structure with a solar array turned out to be 5 degrees Fahrenheit cooler than buildings in the direct Sunlight. One would expect the shaded roof-tops to be cooler, yet the surprise came from how much cooler they turned out to be. In one study, a building was found to experience a 38% reduction in the amount of solar heat directly hitting the roof, indicating that savings can exceed the 5% estimate in the long run.

Your solar panels essentially act as roof shades, taking the brunt of the Sun’s heat.  Air between the panel and the roof helps dissipate this heat as most solar arrays are set up on a tilt. It was found that at night, solar panels also assist in preserving heat stored in the building, being an effective insulator in the winter.

Solar panels can be fastened to most rooftops with minimal perforation or structural interference. There is a wide range of racking and mounting hardware options available, and most of them can be installed by the homeowner or a general contractor.

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