SolarReviews is proud to announce the release of its 2023 Solar Panel Manufacturer Scoring System.

The scoring system has been formulated after extensive discussion with industry leaders and offers a transparent and unbiased scoring methodology for solar brands. It has been used for the first time to score the SolarReviews 2021 Top 20 Solar Panel Manufacturer Rankings.

The rankings are designed to provide homeowners insight into the likely quality and performance of solar panels over their full life. The term "full life" is key here, as solar panels are a long-term investment with a warrantied life of between 25 to 30 years.

Our full list consists of 20 solar panel manufacturers. Here are the 2023 top ten manufacturers who scored the highest points overall.

Why was an expert rating system needed for solar panel manufacturers?

After running a reviews website for the solar industry for many years, it was clear to our editorial committee that consumer reviews alone were not enough. Consumer reviews, as useful as they are, are typically written within the first year of the panels‘ life and therefore aren't as good at predicting solar panels’ performance over time. An expert rating system was needed to judge criteria not visible to consumers.

We don't just judge a manufacturer's current product line. Instead, we take a holistic approach to our scoring system that includes factors such as the company’s financial health and reliability and the quality of the installation companies that choose to install each brand.

Read on to see the full list of ranking factors, explanations of why they are important to homeowners, and how each was scored.

The assessment was conducted based on facts and information available as of January 15, 2023.

Ranking factors

Below is a list of the criteria we used to score the solar panel companies, and the weights we assigned to each.

• Value (30%): Solar panels are a substantial investment, and their high upfront cost deters many homeowners from going solar. As such, we think solar panel cost is a significant factor to consider when rating solar panels.
• Module quality (20%): This is an assessment of the spec sheet performance of each company's top residential solar panel, specifically their efficiency rating and temperature coefficients. Panels that take up less space and perform more consistently in different climatic conditions will earn a higher score.
• Company financial performance (20%): This factor assesses the financial health of the solar panel manufacturer. This serves as the best possible indicator of whether the company will be around to honor any warranty claims that may arise.
• Warranty (10%): Here, we look at both the product and performance warranty. The former reflects the module's reliability, while the latter tells you how panel performance will hold up with each passing year.
• U.S. investment (10%): This factor assesses how committed each brand is to the U.S. market.
• Dealer network (10%): This reflects the availability of the brand among solar installers.

Let’s take a deeper dive into each category and see how we assigned scores for each.

In the U.S. investment ranking factor, manufacturers with production facilities in America earn higher points. Image source: Jacksonville Daily Record

1. Value - 30%

Points assigned for: Cost per watt

To ascertain the value proposition of each solar panel brand, we assigned points based on the cost per watt of their flagship solar modules as of the time of scoring (January 2023). The lower the cost per watt, the higher the score.

Comparing solar panel brands based on cost per watt is the standard in the solar industry. Cost-per-watt figures are useful as they allow a like-for-like comparison between solar panels of different power outputs. For instance, it is more meaningful to compare the cost per watt of a 6,000-watt system that uses 20 300-watt panels versus a system that uses 15 400-watt panels than it is to compare the cost per panel.

We found that the solar panel brands offering the best value (AKA the cheapest) were roughly half as expensive as those offering the lowest value (AKA the most expensive).

Highest scores for value: Boviet Solar, Canadian Solar, Qcells

Lowest scores for value: Solaria, SunPower Maxeon, REC Group

2. Module quality - 20%

Points assigned for: Panel efficiency; Temperature coefficient

When judging module quality, we decided to focus on the two most important items on the specifications sheet: panel efficiency and temperature coefficient relating to the maximum power output (Pmax). Each factor accounts for half the total points in this category.

Panel efficiency measures the amount of sunlight that gets converted into energy. A panel with a higher efficiency rating requires less space to produce a given amount of energy, thus taking up less space.

The temperature coefficient of Pmax tells us how well a panel will perform in real-world temperatures. The lower the temperature coefficient, the better - this means there is less power loss for every degree the surface temperature of the panel goes above 25°C. (Panels run about 20°C hotter than the ambient outdoor temperature, so your panel will almost certainly be running at higher than 25°C for most of the year).

These two factors are not just meaningful on their own; they also speak to the solar panel’s overall production quality. To achieve high-efficiency ratings and low-temperature coefficients, a company must employ advanced, highly-automated manufacturing processes.

Highest scores for module quality: SunPower Maxeon, REC Group, Canadian Solar, JA Solar

Lowest scores for module quality: Mission Solar, Hyundai, Silfab Solar

3. Financial visibility and strength - 20%

Points assigned for: Public listing; Availability of financial statements; Operating revenue and profitability

This category could just as well be called, 'How likely is it that the solar panel manufacturer will be around for the next 25 years?’

The question is important because solar panels are a unique product - they are designed to work for decades, and manufacturers guarantee a certain performance level for 25 years.

We answer the question by looking at several indicators of financial health.

The first step is determining whether the company’s financials are visible and, therefore, easy to assess. Companies that publish their financial statements or are publicly traded get more points.

Next, we look at revenue. We assign points to companies based on the size of their overall revenue, as we deem larger manufacturers more likely to survive. Large manufacturers with revenue north of $2 billion earn the maximum number of points, while smaller players with under $100 million earn the least.

Finally, we look at profit. We assign extra points to companies that reported a net profit in the most recent financial year. The logic here is simple: profitable companies have the best chance of staying in business and expanding, while unprofitable companies have less rosy future prospects.

Some of the manufacturers we’ve rated are private or wholly-owned subsidiaries of larger groups that offer no visibility into their financial position. Where this was the case, we looked at the financials of their parent company but discounted these scores by half. Our logic is that while a subsidiary can benefit from the parent company's resources and deserves some points for being part of a large and/or profitable company, a subsidiary is also at risk of being cut off if it is not profitable.

Highest scores for company financial performance: Canadian Solar, JA Solar, Hyundai, Qcells, Phono Solar

Lowest scores for company financial performance: Aptos Solar Technology, Seraphim, Axitec Solar, Yingli, Silfab Solar

4. Warranty - 10%

Points assigned for: Product warranty length; 25-year performance warranty

The manufacturer's warranty is an important consideration when buying a product like solar panels since they are built to last for a quarter-century or longer.

When it comes to product warranties, we’ve awarded higher points to the brands that cover the longest periods, i.e., between 20 to 30 years.

For the performance warranty, we’ve also assigned the highest points to solar panels with the lowest degradation rates, meaning they will see the smallest output drop-offs over their warrantied lifetime. The panels that scored highest here indicate that they will produce 90% or higher of their rated output at the 25-year mark.

You may be wondering why we’ve decided to limit the warranty to just 10% of our score. The reason is simple: while warranty promises are useful, we believe that the company’s ability to honor the warranty is what really matters, a fact that is best reflected by its financial performance score.

Highest scores for warranty: SunPower (Maxeon), REC Group, Qcells, Solaria

Lowest scores for warranty: JA Solar, Hyundai

5. U.S. investment - 10%

Points assigned for: Headquarters or offices in the U.S.; American manufacturing; Attendance at U.S. trade shows and events

Many consumers prioritize buying locally and supporting the local economy. To reflect this, we assigned more points to companies with global headquarters in the U.S., with fewer points if they only have offices here. We also awarded extra points to manufacturers with solar panel production facilities here in the U.S. and for recent attendance at major American trade shows and industry events.

The companies that score highest in this category are American-headquartered companies with local production facilities. However, some big foreign manufacturers score relatively high as well, having spent hundreds of millions of dollars to set up U.S. factories and strengthen their local marketing and support.

Our logic here is that if a company has spent a lot of money building up its brand equity in the U.S, it is more likely to honor warranties to protect the reputation of its brand.

Highest scores for U.S. investment: Mission Solar, Qcells, SunPower (Maxeon), REC Group

Lowest scores U.S. investment: Phono Solar, Boveit Solar, Yingli

6. Dealer Network - 10%

Points assigned for: Share of residential installations

A manufacturer may offer great solar panels, but this is of little use if local dealers and installers don't carry their product. We allotted 10% of our score to reflect product availability and the quality of the installers that recommend the brand. Scores are assigned on a sliding scale based on brand market share in California between January 2018 and November 2022.

The companies that scored the highest each accounted for between 14.2% and 17% of California home solar panel installations over this period.

Highest scores for dealer network: SunPower Maxeon, Qcells, Silfab Solar, Solaria

Lowest scores for dealer network: Phono Solar, Hyundai, Boviet, Axitec