How We Review Solar Companies, Panels, Batteries and Inverters

CNET's approach to solar product and company reviews follows from its tradition of testing and reviewing new technology: the exciting, the overhyped and the world-changing. Through it all, CNET has had a commitment to honest, fair, transparent and editorially independent testing.

Those commitments inform our reviews of solar companies, panels, batteries and inverters. While we can't conduct hands-on testing or go through the purchasing process, we thoroughly research them and conduct interviews with company spokespeople, focusing on the things we can measure and ignoring the noise and spin. It's all filtered through our ongoing reporting on the industry.

Here's a detailed look at how we evaluated them. 

How we evaluate the best solar companies 

The list of solar companies we choose to review is created with input from a variety of sources. 

Some companies are chosen because our editors and writers recognize them as companies the public needs to know about. They could be companies with large market shares, like Sunrun or Tesla, which readers are likely to encounter when searching for solar panels. Or they could be offering a new and potentially disruptive solar solution, like GAF Energy.

The selection of the companies we review is also influenced by which companies the public is most interested in learning more about, as measured by search volume. We also review this list when new affiliate partnerships are made between solar panel companies and CNET or its parent company, Red Ventures. While partnership status might prompt us to review a specific company, it does not influence the scores or recommendations we give. No advertiser, affiliate partner or business interest dictates what we write or how we review it.

Our methodology

Reviewing solar companies in a hands-on way is difficult, if not impossible. Instead, we rely on thorough research, our ongoing coverage of the industry and conversations with people at the company. We crafted our methodology to accurately measure things that matter to our readers, ignore those things that don't make a difference and do so in a way that allows for meaningful comparison between companies.

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Solar companies are scored on criteria that fall into three general buckets: equipment, warranties and service.

Within the equipment category, companies receive scores for the panels, inverters and batteries they install. Warranties include the guarantees on the panels, workmanship and weatherization against leaks. Companies earn points for service if they offer a price match, a meaningful level of price transparency and a well-rated app for monitoring solar production. They lose points if there are major issues pertaining to customer service (lawsuits, investigations or clear reputations for shoddy service). These issues will always be detailed in the review.

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Here's how the scoring breaks down. Each category we consider in scoring gets a score out of five, sometimes on a simple scale, other times by gaining points for offering equipment or services with specific characteristics. Each category counts for 5 or 10% of the final score.

Solar companies without a score

In some cases, we lacked the information needed to accurately score a company. Either the information was not publicly available, we couldn't get in contact with the company or it declined to provide the necessary information. 

What we didn't consider in the score

We don't consider average prices in our score. While price is clearly a consideration for you, it's hard to measure in a way that makes for useful comparisons between companies. The price of a solar installation varies from state to state because of differences in the size of a solar system, labor and permitting costs and other regional factors. You should always get multiple quotes when shopping for solar panels, because prices can vary so much. 

We do consider whether a company is transparent about pricing or offers a price match, as those are easily verifiable and will translate across regions.

We also don't consider how many states a company operates in, though our list is made up of companies with a larger service area. We assume you care that a company operates in your state, not others.

CNET's solar shopping philosophy

We've rated and reviewed companies in a way we find to be most helpful to solar panel shoppers. However, you should always shop around, getting multiple quotes before deciding to move ahead. You should also go in informed: Understand your energy use and costs, the local and national incentives available to you, like net metering or tax breaks, and your likely payback period.

How we chose and ranked the best solar panels

The solar panels on this list are some of the most widely installed solar panels in residential solar applications in the United States. If you're collecting and comparing quotes for a solar installation at home, you're likely to come across one of these brands. Luckily, we did the legwork for you and compiled specification data from the most popular solar panel brands to compare against each other.

If your preferred panel, or those you're quoted, aren't on this list, you can find their specs the same way I did. Most solar panel manufacturers make their products' specifications and warranties readily available online on their websites. It's just a matter of finding where on the website it's listed.

The five best solar panels listed at the top of this article came out on top after all the solar panels we looked at were put through our scoring methodology.

We scored the panels on their efficiency (25% of the final score), maximum wattage available (15%), temperature coefficient (15%), production warranty level (25%) and production warranty length (15%). The final 5% of the score comes from whether or not the company offers an all-black option, which has a more attractive look to some people.

Here's how the scoring breaks down.

How we evaluated the best solar batteries

First and foremost, it's important to call out that not every solar battery is right for every home. Solar is a very site-specific and personalized decision process, so it's a little tricky to pinpoint exactly which solar battery is the "best" battery for your home's energy needs without doing an on-site consultation. It should also be said that we didn't have any form of hands-on testing with any of the batteries we scored. However, there are ways to evaluate and compare these batteries in order to find the stand-outs. Here's how we developed our list of top solar batteries.

First, we determined which categories would be used to evaluate each battery's efficiency, performance, capacity and value. We also weighted each category. The weight of each category reflects the importance we felt was relevant to the average consumer. 

After a thorough research process, these were the categories we chose to evaluate each battery on.

• Battery modularity (stackability): 20%
• Warranty: 20%
  
• Round-trip efficiency: 15%
  
• Depth of discharge: 10%
  
• Power output: 10%
  
• Price: 10%
  
• Customer reviews: 10%
  
• Battery capacity: 5%
  

We looked at the most widely available batteries on the market and collected the data for each category to compare the numbers. Each category (for every battery) was given a tier-style rating (from 1 to 5) to evaluate which aspects of each battery were above average (among our list), just average or below average. 

How we evaluated the best solar inverters

Like any other type of solar equipment, not every solar inverter is right for every home. Solar is a site-specific and personalized decision process, and finding the "best" inverter for your home would be extremely difficult without an on-site consultation. We also only looked at single-phase, residential-use inverters that are included in the California Energy Commission's Solar Equipment Lists Program for this list. We did not perform any hands-on testing. 

Instead, we focused on relatively objective ways of evaluating and comparing these solar inverters to see which ones stand above the competition. Here's how we found the best solar inverters. 

The first step was determining which categories would be used to evaluate each inverter. We then gave each category a weight. The weight we gave each category reflects the importance we felt was relevant to the average consumer. After a thorough research process and speaking with some subject matter experts (who did not influence the choices we made for this list), these were the categories (and their weights) we chose to evaluate each inverter on.

• Warranty: 25%
• California Energy Commission efficiency: 25%
  
• Peak or maximum efficiency: 10%
  
• User interface or consumer app: 15%
  
• Inverter size options: 10%
  
• Price: 5%
  
• Company reputation: 10%
  

We looked at the most popular inverter brands on the market and collected the data for each category to compare the numbers. Each category (for every inverter) was given a tier-style rating (from 1 to 5) to evaluate which aspects of each inverter were above average (among our list), just average or below average.