For example, at 26C (79F) a REC Alpha Pure would produce 0.24% less energy than at 25 degrees. At 29C (84F), it would lose just shy of 1% of its production.

Solar panel efficiency by type

There are three main types of solar panels, and each converts sunlight into power at a different rate. Here’s a look at the three types:

• Monocrystalline solar panels: Monocrystalline panels, which are made from a single silicon ingot sliced into thin wafers, are the most efficient, at 17% to 22%. They’re also fairly pricey, generally around $1 to $1.50 per watt. Almost all residential solar panels installed today are monocrystalline.
• Polycrystalline solar panels: Polycrystalline panels generally range from 15% to 17%. They’re more affordable, usually between 90 cents and $1 per watt.
• Thin-film solar panels: These panels are less expensive but also relatively inefficient. They’re typically used in commercial installations. They tend to be 10% to 13% efficient and cost between $1 and $1.50 per watt.

Is solar panel efficiency important?

All things being equal, it would make sense to choose a higher-efficiency solar panel over one with a lower rating. High-efficiency solar panels typically cost more than lower-rated ones, so making the best choice becomes a matter of balancing your financial goals with what your preferred installer offers and other considerations like brand and aesthetics.

“It’s just one part of the equation,” said Ciolkosz. “The bigger question for the end user is the economics and how it’s paying off.”

Is there a case where efficiency might be a worthwhile consideration?

“If you have one of those tiny homes on HGTV,” said Tom Beresnyak, a Pennsylvania State University extension educator. 

If you’re limited by available space for solar panels, you might want to squeeze out as much solar energy as possible from that space, although if your state allows it, a community solar subscription still might be a better choice financially, Beresnyak said.

Can solar panels be 100% efficient?

No, but the panels listed here aren’t the most efficient solar panels ever made — just commercially available ones marketed for homes. 

Research into solar cells (the energy-producing components that make up solar panels) has produced much higher efficiencies in the lab. The National Renewable Energy Laboratory tracks the highest efficiencies achieved in standardized lab conditions. The highest-ever solar cell efficiency was 47.6%, recorded in June 2022.

What should I consider when choosing a solar panel company?

Because there’s no one-size-fits-all solar solution, there’s no one-size-fits-all advice for choosing a solar company. The best approach is to get quotes from multiple installers before deciding. Choose the company that has offered you the best fit for your needs, you trust to do the work and has answered all your questions.

You should understand your energy usage before going solar and decide whether your goals are to completely replace that energy, save as much money as possible or achieve something else. From there, it’s a matter of measuring competing quotes against your goals.

The Department of Energy recommends that you choose an installer with credentials from a respected third party, like the North American Board of Certified Energy Practitioners, which operates an online directory of certified installers that you can filter by state and certification.

Installers should definitely assess your roof condition because removing panels at a later date to replace a roof will be an additional cost. They should also be able to transparently answer questions about the system’s design and why they’re making their specific proposal.

“The installer can make a huge difference because the angle and the mount [are important for] maximizing what you have at that location — a skilled installer is still going to be the real key in your long term production,” Beresnyak said.

Read more: Want something smaller than a whole-home solar system? See our picks for the best portable solar panels and solar generators.

How we chose and ranked the most efficient solar panels

The panels on this list were chosen because they’re some of the most commonly installed panels and are likely to appear on quotes for solar installations. If you’re quoted for panels that don’t appear on this list, you can check their efficiency rating and other specifications in the same way I did. Here’s how.

Solar panel manufacturers publish data sheets for solar panels, which detail their dimensions, performance metrics and internal chemistry. If your solar company doesn’t provide you with them, you can access them by clicking on the company name in the table above. (Many of the links lead to PDFs.) From there, it’s a simple matter of comparing statistics.

The panels featured here are the most efficient offerings from each of these companies. They may sell other panels that would appear higher on the list. In general, the higher a company appears on this list, the more efficient all of the solar panels they offer are.

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