Buying guide for best solar panels
Part of going solar is altruistic. An early study conducted in the United States and Europe concluded that switching from fossil fuel to solar power could potentially cut air pollution by 90%. That's a remarkable number. But there's a second, more immediate and personal benefit to using solar panels. Free electricity anywhere there is sun!
Solar panels are amazingly versatile. And you don't have to remortgage your house to reap the benefits of using clean energy. You can start small and affordable with a portable panel designed to charge your USB devices, or you can step up to something that brings convenience to camping, allowing you to charge 12-, 24-, or even 48-volt batteries with nothing more than a clear day. Of course, you can make the big commitment and cover your roof in solar panels and live off the grid, so to speak. Whatever you want to power, there's a way to get the job done with solar.
But if you're like most people, charging your phone with the sun seems like magic, not science. BestReviews is here to help demystify solar power and give you the information you need to purchase panels with confidence. If you want a little more guidance after you read this shopping guide, jump back to the top of the page where we've narrowed the selection to five of the best solar panels on the market.
The science of solar power
Way back in the 1800s, a French physicist named Edmund Becquerel realized that some materials produced a small electric current simply by being exposed to the sun. His discovery of this photovoltaic effect provided the operating principle for the solar cell.
Solar cells
The most common solar cells are made of two different types of silicon layered together to encourage electron movement. The silicon is sandwiched between two outer conductive layers and covered by glass with an antireflective coating (light that bounces off a solar panel is wasted). When light hits these cells it catalyzes a specific movement of the electrons, which creates the flow or current that we call electricity.
For a visual, think of meandering cattle being herded into a cattle chute. The cows won't enter the chute on their own, but under the direction of the herder, the cows travel to their required destination. In a solar cell, sunlight is the herder of electrons.
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Module: Since a single solar cell can only produce one-half volt of electricity, these cells are wired in parallel to create a module.
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Panel: The modules, in turn, are connected together to create a solar panel.
- Array: Several solar panels can be connected to form an array, that familiar, futuristic-looking grid you see on roofs.
Types of solar panels
The technology of solar power is advancing rapidly. New materials, techniques, and processes are constantly being discovered and tested. Currently, however, there are only three broad categories under which we can place all solar panels: monocrystalline, polycrystalline, and thin film.
Monocrystalline
Monocrystalline is "grown" from a single seed crystal that is dipped into molten silicon. The seed is drawn up and rotated, forming a tubular ingot. This ingot is shaved and sliced to make the familiar flat black wafers with rounded corners that you see on many solar panels.
Pros:
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Made from the highest-grade silicon, these panels are the most efficient.
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These panels offer the highest output.
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These panels last the longest.
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Monocrystalline panels perform well in warm weather (up to about 77°F).
Cons:
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Because of the process and the waste, these panels are the costliest to produce.
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If a panel is only partially covered by debris or shade, the entire panel can cease to function.
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The efficiency of these panels decreases as the temperature climbs over 77°F (losing about 1% efficiency for every few degrees hotter).
Price: A single 100W monocrystalline solar panel costs about $105 to $170.
Did you know?
Solar panels have no moving parts, so they require very little maintenance. The best way to take care of them is to make sure they remain clean and free of dirt buildup.
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Polycrystalline
Polycrystalline is created by dropping the seed crystal into molten silicon. The mixture is then poured into a square mold. These panels feature square-shaped silicon that has a more uneven or crystalline appearance on the surface.
Pros:
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Since the process for creating polycrystalline panels is less involved and creates less waste, this is a more affordable option.
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These panels are a more environmentally friendly choice.
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Many argue that the lower price makes these panels the better value.
Cons:
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Polycrystalline panels are not as efficient as monocrystalline panels.
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These panels don’t last as long as monocrystalline panels.
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You'll need more of these panels to accomplish the same task.
Price: A single 100W polycrystalline solar panel costs about $99 to $104.
Thin film
Thin film panels are made by layering any of several different photovoltaic materials (amorphous silicon, cadmium telluride, copper indium gallium selenide, or organic photovoltaic cells) onto a substrate. Thin film panels are a rapidly emerging technology and not as readily available to the consumer as other types. It is a category to watch as technological advances continue.
Pros:
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These panels are flexible and lightweight.
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Thin film panels are adaptable to many different situations.
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Higher temperatures and shade have less impact on the performance of these panels.
Cons:
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Thin film panels are the least efficient of the three types.
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These panels require more room for the same power output as other types.
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Thin film panels are the most susceptible to the effects of weather.
Price: A single 100W thin film solar panel costs about $160 to $190.
Solar panel uses
What exactly can you do with a solar panel? The answer is virtually anything!
Solar modules can be used to power small devices, such as a handheld calculator or decorative outdoor lighting. Solar panels can make stop signs flash with attention-getting lights. They can power traffic signals and light up a traffic message board. You can use them to charge your USB devices and recharge larger batteries when camping. If you have enough voltage in your array, you can even power household appliances.
Some of the more popular uses for solar panels include powering phones, tablets, speakers, radios, mini fridges, and more. The technology has even been integrated with clothing so you can wear your power while hiking. If the conditions are optimum where you live, your entire home could be powered by the sun. And if you make more electricity than you use, you can sell it to your local power company.
Anything you can do with electricity, you can do with the right array of solar panels.
FAQ
Q. How long do solar panels last?
A. Although there are no mechanical parts that can wear out, because of natural chemical breakdown, a solar panel can lose up to 1% of its efficiency each year. When it drops to 80% efficient, it's time to start thinking about getting a new panel. Using this data, it’s safe to say that most panels will last at least 20 years.
Q. How do I clean my solar panels?
A. Dust, dirt, debris, and bird droppings can accumulate and cause your solar panels to be less efficient. The best way to clean the glass that covers your panels is with water from a garden hose. If that's not enough, fill a bucket with warm water and gentle soap – nothing harsh or abrasive. Use a soft cloth or sponge to gently wipe away grime, being careful not to mar the glass in any way.
Q. Will my solar panels work with a full moon?
A. The moon itself isn’t a source of light; it’s merely illuminated by the sun. Because of this, it produces no photons, the key element in catalyzing electric current in silicon. Without photons, solar panels will not work.
