How do solar panels work?

According to the U.S. Office of Energy Efficiency and Renewable Energy, solar panels utilize photovoltaic cells to convert sunlight into energy. UV rays from the sun are absorbed by the photovoltaic cells and an electric charge is released. An internal electrical field creates a flow of energy that can then be used, converted, or stored in a battery.

Can every roof take a solar panel?

For the most part, yes; it doesn't matter if the roof is slanted or flat, although flat roofs may require additional mounting, to prop them at the optimum angle to capture the sun's rays. Slate or wood roofs may be more difficult than asphalt shingles to mount a solar panel on since they aren't as easy for installers to walk around on. Also, when a solar panel is installed on a slate or a concrete tile roof, those tiles often need to be removed and replaced with flashing. If not done 100 percent correctly, a less-than-perfect job can result in a leaky roof.

How efficient are solar panels?

Note that solar panels in sheer terms aren't efficient producers of energy because most solar energy is carried away as heat. Most residential solar panels have efficiency ratings of around 15 to 20 percent, which means they are converted that proportion of solar energy into electricity. Monocrystalline solar panels are the highest-rated types of solar panels. Higher-efficiency solar panels, with efficiency ratings above 22 percent, may be an option for smaller roofs.

Do shade and temperature affect solar panels?

Shade negatively impacts the efficiency rating of your solar panel, but most newer solar panels can generate electricity on cloudy or overcast days. Thin-film solar panels have a reputation for better performance in shady conditions than monocrystalline or polycrystalline panels. An MPP inverter, multi-string inverter, or microinverter can maximize voltage output despite shady conditions. Temperature also affects solar panel performance. Panels absorb the sun’s rays, and with that comes a significant rise in the solar cells' temperature. The temperature coefficient tells you how much efficiency the panel loses in terms of voltage output for every degree above 77 degrees. A lower temperature coefficient on a product's spec sheet is better.

Do solar panels require maintenance?

There is very little preventative maintenance required for most solar panel setups. A visual inspection for broken panels or loose connections is wise, but damage to the system will likely be first noticed by means of a drop in solar energy production. You may choose to wash your solar panels of dirt, debris, bird droppings, etc. once a year. Keep in mind that you should use only water and avoid high-pressure water, abrasive sponges, solvents, or hard water , as those may damage solar panels.

The 6 Best Solar Panels of 2023

Solar panels provide a way to capture the sun’s energy and put it to work to power your home. Installing a solar-power system can have large up-front costs but can free you from paying energy bills to your local utility company. The latest products can generate electricity even on cloudy days.

We researched dozens of solar panels—including those that require professional installation and kits for small-scale DIY projects—evaluating effectiveness, durability, and overall value. Our best overall pick is the Renogy 100W Monocrystalline Solar Panel, thanks to its compact design, ability to withstand natural elements, and overall efficiency.

Here are the best solar panels for every type of home.

Our Top Picks

Best Overall:

Renogy 100W Monocrystalline Solar Panel at Amazon

Jump to Review

Best Value:

Nature Power Polycrystalline Solar Panel at Home Depot

Jump to Review

Best Splurge:

Goal Zero Boulder 100W Monocrystalline Solar Panel at Amazon

Jump to Review

Best Portable:

Jackery SolarSaga Portable 100W Solar Panel at Amazon

Jump to Review

Best for Pools:

Smart Pool S601 Pool Solar Heaters at Amazon

Jump to Review

Best for RVs:

Renogy 200-Watt 12-Volt Monocrystalline Solar Starter Kit at Amazon

Jump to Review

In This Article

Our Picks
What to Look for
FAQ
Why Trust The Spruce

4.6

Courtesy of Amazon

View On Amazon View On Home Depot View On Lowe's

What We Like

High efficiency rating
Lightweight
Compact
Designed to weather elements

What We Don't Like

No additional items included

For the most efficient solar panels, start your search with monocrystalline panels. This type of solar panel can be more expensive but converts the sun's rays to solar energy with the highest efficiency rating, compared with polycrystalline or thin-film panels. In the case of these compact and lightweight solar panels by Renogy, you see solar efficiency ratings of 18 to 21 percent, according to the manufacturer. This is at the high end of the spectrum when you realize that the vast amount of solar energy is dissipated as heat.

The Renogy 100 Watt Monocrystalline Solar Panel was designed to save space and weigh less, thanks to a lightweight aluminum frame. This makes these solar panels a good choice for roof installation and other applications. Specifically designed to weather the elements, these popular solar panels have been rated to withstand wind speeds up to 130 miles per hour, and snow loads up to 125 pounds per square foot.

This model has an IP65-rated junction box to protect against dust and rain, along with IP67 connector cables. To convert the energy into standard AC electricity, use these cables to connect this panel to an inverter, which is similar to a transformer. You can also connect multiple Reonogy Monocrystalline panels together to create a larger array of solar panels for increased energy production.

Price at time of publish: $115 (single panel)

_{Type: Monocrystalline | Dimensions: 41.8 x 20.9 x 1.38 inches | Wattage: 100 watts}

Nature Power 110W Polycrystalline Solar Panel with Inverter and Charge Controller

Courtesy of Home Depot

View On Home Depot

What We Like

Budget-friendly
Convenient
Can connect multiple Nature Value panels

What We Don't Like

Need to upgrade to add more panels
Needs an additional 12-volt battery

If you want to combine convenience and value, consider this solar panel package from Nature Power. The bundle includes a 110-watt polycrystalline panel, along with an 11-amp charge controller, and 300-watt string inverter. You need to supply a 12-volt battery to store the captured solar energy and complete the setup.

You can connect multiple Nature Value solar panels for expanded energy output, but keep in mind that adding. more panels require upgrading the controller. The panel comes with a 25-year limited warranty, and the charge controller and power inverter come with 1-year limited warranties.

Price at time of publish: $405 (including controller and inverter)

_{Type: Polycrystalline | Dimensions: 39.7 x 1.4 x 26.6 inches | Wattage: 110 watts}

Goal Zero Boulder 100W Monocrystalline Solar Panel

Courtesy of Amazon

View On Amazon

What We Like

18 percent efficiency rating
High-quality monocrystalline solar cells
Integrated kickstand
Durable frame and reinforced corners

What We Don't Like

Other alternatives cost less

Goal Zero makes go-anywhere solar panels that have a reputation for durability and longevity. Just be prepared to spend more than you might expect for this 100-watt panel. It costs about twice as much as a budget 100-watt solar panel, but offers a substantial 18 percent efficiency rating, thanks to the high-quality monocrystalline solar cells.

The Goal Zero Boulder 100W Solar Panel is built with a durable aluminum frame. It can be permanently installed, but it’s most often used as a travel option with a portable generator. The integrated kickstand provides angled support, though it’s worth noting that you can’t adjust the angle to optimize the amount of sunlight reaching the panel. It comes with a 2-year warranty.

Price at time of publish: $250 (panel, cord, and kickstand)

_{Type: Monocrystalline | Dimensions: 40 x 26.75 x 1.75 inches | Wattage: 100 watts}

Jackery SolarSaga Portable 100W Solar Panel

Courtesy of Amazon

View On Amazon View On B&H Photo Video View On Jackery.com

What We Like

Portable
Lightweight
Quick setup

What We Don't Like

Not waterproof

For solar power anywhere the sun shines, consider a portable panel. Commonly used for camping, outdoor events, or off-grid uses, a portable solar panel is quick to set up and can give you the power you need. Use it to charge your devices, operate LED lights, or power a solar generator.

The Jackery SolarSaga is a popular folding solar panel. This 100-watt lightweight model is made with ETFE, a fluorite-based plastic, and is 100 percent permeable for UV rays. This translates into more light reaching the panel, resulting in an efficiency rating of 23 percent for the unit.

Note that this model is designed for short-term setups and temporary applications—it’s not waterproof, so you shouldn't permanently mount it outside or leave it exposed to rain or snow. Jackery also manufactures 60-watt and 200-watt versions of this solar panel.

Price at time of publish: $299

_{Type: Portable and made with ETFE | Dimensions: 22.83 x 19.69 x 2.36 inches | Wattage: 100 watts}

The 21 Best Emergency Kit Essentials of 2023

Courtesy of Amazon

View On Amazon

What We Like

Cost-effective
Mounts to your roof to save space

What We Don't Like

Larger pools need more than one panel

Another popular use for solar energy is to warm up chilly pool water, using the sun’s energy. Unlike photovoltaic panels that are used to generate electricity, this type of solar system directly heats water by pumping the water through tubing. It is a passive means of heating your pool and can be a cost-effective alternative to conventional pool heaters. The Smart Pool S601 features a polypropylene tubing system that warms incoming pool water by passing it through an array measuring 4 x 20 feet.

While some solar panels for pools take up square footage on the ground around your pool, this model mounts to your roof for out-of-the-way energy production. Every panel provides 80 square feet of surface area. Larger pools require more than one solar panel for maximum heating results.

Price at time of publish: $289

_{Type: Passive heating | Dimensions: 240 x 54 x 2 inches | Wattage: Not applicable}

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Renogy 200-Watt 12-Volt Monocrystalline Solar Starter Kit

Amazon

View On Amazon View On Home Depot View On Walmart

What We Like

Good starter system
Contains all mounting hardware
Packs 1,000 watts of power

What We Don't Like

Battery, inverter sold separately
Online-only user manual

For those RVers wanting solar power for their rigs, this product from well-regarded manufacturer Renogy is a reliable choice. For under $300, you get a kit that includes two 100-watt 12-volt monocrystalline solar panels, along with a charge controller, adapter kit, 8-foot cable, and two sets of mounting brackets. The manufacturer claims 5 hours of direct sunlight can produce an average 1,000 watts of power, with 22 percent cell efficiency.

The controller supports four-stage battery charging, to maintain optimal performance. A multi-layered TPT backsheet is designed to effectively dissipate heat. The connectors are rated at IP67, meaning they should effectively keep out dust—essential when you're on the road—and rain. If you wish to monitor your system's status by smartphone, you can connect a Bluetooth module (sold separately) to the RS232 communication port and keep track with a downloaded app.

We like that the kit comes with pre-drilled holes, as well as the necessary hardware that allows for fairly easy installation on the the roof of an average-size RV. We should note that this price includes the controller but not a battery. Neither does it include a power inverter, which converts solar DC energy to standard AC electricity. Also, as with many products these days, the user manual is available only online.

Price at time of purchase: $366

_{Type: Monocrystalline | Dimensions: 20.9 x 1.38 x 41.8 inches | Wattage: 1,000}

https://www.thespruce.com/best-portable-generators-4149982

Final Verdict

The Renogy 100W Monocrystalline Solar Panel delivers up to 100 watts of solar energy and can be installed for residential home use or on-the-go applications, like your RV or boat. With an energy efficiency rating of 21 percent, it’s the most efficient solar panel on our list. If you're a newbie looking for a solar system for your RV or motor home, we recommend the Renogy 200 Watt 12 Volt Monocrystalline Solar Panel Starter Kit, which comes with all the hardware you need to power up quickly and easily.

Type

There are three primary types of solar panels: monocrystalline, polycrystalline, and thin-film. The differences between each relate to the type of solar cell technology used in the panel.

Monocrystalline panels are generally the most expensive but also have the highest energy efficiency ratings. They also require less space to reach the kind of power output you desire, so you likely need fewer panels on your roof. Manufacturers say these types of solar panels also have greater heat resistance, and last longer. You can frequently find these products with warranties of 25 years or even longer. The main disadvantage is these solar panels cost more than other types.

Polycrystalline solar panels resemble "mono" panels, although they tend to appear blue in color, as opposed to black. They are more affordable, last about as long as mono panels, and retain better effectiveness as the temperature rises (lower temperature coefficient). But they take up more space than mono panels and don't perform as well in cloudy weather.

Thin-film solar panels are layered strips of 1-micron-thick materials that capture solar energy, like the other two types. Unlike the others, they are not rigid but extremely flexible. There are three types, with names all relating to their composition: amorphous silicon, cadmium-telluride, and copper indium gallium selenide. All cost less than mono or "poly" crystalline solar panels and function better in high heat. But they have lower energy efficiency ratings than the other types, require more surface area, and don't last as long.

Energy Efficiency

The energy efficiency of a solar panel refers to how much of the received sunlight the panel's photovoltaic cells convert into electrical energy. A higher percentage is better. Top-quality monocrystalline solar panels often have energy efficiency ratings of 18 to 20 percent. (Keep in mind that most solar energy is dissipated as heat.) Polycrystalline panels usually have efficiency ratings of 13 to 15 percent. Thin-film panels may only convert as little as 7 percent.

Durability

Since solar panels are outdoor fixtures, durability is important to consider. Many solar panels designed for fixed installation (such as on a house's roof, RV, or boat) have passed ASTM testing to evaluate their ability to withstand wind up to 130 miles per hour and snow loads up to 125 pounds per square foot.

While most panels also have sealed junction boxes to prevent damage from dust or moisture, some portable, folding solar panels are not weather-resistant. If you plan to install your panels or leave a portable solar outside—rain or shine, then it’s important to look for one that is water-resistant. Look for an IP rating of 66 or higher.

FAQ

How do solar panels work?

According to the U.S. Office of Energy Efficiency and Renewable Energy, solar panels utilize photovoltaic cells to convert sunlight into energy. UV rays from the sun are absorbed by the photovoltaic cells and an electric charge is released. An internal electrical field creates a flow of energy that can then be used, converted, or stored in a battery.
Can every roof take a solar panel?

For the most part, yes; it doesn't matter if the roof is slanted or flat, although flat roofs may require additional mounting, to prop them at the optimum angle to capture the sun's rays.
Slate or wood roofs may be more difficult than asphalt shingles to mount a solar panel on since they aren't as easy for installers to walk around on. Also, when a solar panel is installed on a slate or a concrete tile roof, those tiles often need to be removed and replaced with flashing. If not done 100 percent correctly, a less-than-perfect job can result in a leaky roof.
How efficient are solar panels?

Note that solar panels in sheer terms aren't efficient producers of energy because most solar energy is carried away as heat. Most residential solar panels have efficiency ratings of around 15 to 20 percent, which means they are converted that proportion of solar energy into electricity. Monocrystalline solar panels are the highest-rated types of solar panels. Higher-efficiency solar panels, with efficiency ratings above 22 percent, may be an option for smaller roofs.
Do shade and temperature affect solar panels?

Shade negatively impacts the efficiency rating of your solar panel, but most newer solar panels can generate electricity on cloudy or overcast days. Thin-film solar panels have a reputation for better performance in shady conditions than monocrystalline or polycrystalline panels. An MPP inverter, multi-string inverter, or microinverter can maximize voltage output despite shady conditions.
Temperature also affects solar panel performance. Panels absorb the sun’s rays, and with that comes a significant rise in the solar cells' temperature. The temperature coefficient tells you how much efficiency the panel loses in terms of voltage output for every degree above 77 degrees. A lower temperature coefficient on a product's spec sheet is better.
Do solar panels require maintenance?

There is very little preventative maintenance required for most solar panel setups. A visual inspection for broken panels or loose connections is wise, but damage to the system will likely be first noticed by means of a drop in solar energy production.
You may choose to wash your solar panels of dirt, debris, bird droppings, etc. once a year. Keep in mind that you should use only water and avoid high-pressure water, abrasive sponges, solvents, or hard water, as those may damage solar panels.

This article was researched and written by Erica Puisis, a professional writer who specializes in large and small home appliances, along with home improvement features and additions.

This article was edited by Senior Editor Margaret Badore, who has been covering climate change and clean tech for over a decade. Her home is powered by rooftop solar.

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