As the solar power industry continues to grow worldwide and solar companies proliferate, it can be difficult to determine which of the dozens of manufacturers make the best solar panels. In this article, we present the most important considerations to evaluate the quality of solar panels and share recent findings from third-party review sites.
Who makes the best solar panels?
June 21, 2018
Several criteria can be used to evaluate the quality of solar panels:
- Efficiency and yield
Efficiency and Yield:
These related performance measures have a direct impact on how much power your system will produce per watt installed. The more efficient and higher-production your solar panels are, the better your financial return will be over the lifetime of your system. Efficiency refers to the amount of power produced at peak daylight per sunlight absorbed. Yield is determined by high-temperature performance, spectral response (i.e. the ability to capture energy from re-shifted sunlight in the morning and evening can increase production), the use anti-reflective glass or ARG (which enables the panels to capture more light when it’s cloudy or when the sun isn’t directly overhead), and shade performance.
There is a correlation between the expected lifetime of equipment and the length of time a company will guarantee its performance. Three considerations when evaluating a solar manufacturer’s warranty are:
- Equipment: Ask about the warranty coverage for performance as well as materials, and make sure you understand if there are different guarantees on the inverter, monitoring, and other equipment in addition to the panels.
- Process: How much of a hassle will it be to get warranty service? Be sure to understand the required steps to file a claim and try to assess whether the company will make it easy for you to replace, repair, or get reimbursed for any defective parts.
- Longevity: A warranty is only as good as the issuing company's reputation. If your solar company goes out of business before the end of the term, you could be left without coverage. How confident are you that the manufacturer will be around for the duration of the warranty period?
A solar panel’s reliability is another indicator of quality. Independent testing of various solar panels can give you an idea about how well your panels will hold up in harsh conditions such as storms (hurricanes, hail, etc.) and over time. There are several reputable third-party organizations who have expertise in testing the reliability of various solar panels. Fraunhofer, an applied research organization with world-renowned solar power technology expertise, assesses panels from nine top PV manufacturers for resistance to humidity and thermal cycles, potential-induced degradation (PID), mechanical loading, and UV light exposure. TÜV, a global leader in product safety validation based in Germany, conducts Sandstorm Testing to evaluate the harsh stresses of desert conditions. DNV-GL issues an annual PV Module Reliability Scorecard based on their Product Qualification Program, using independent laboratory testing of solar panel reliability across multiple manufacturers. The National Renewable Energy Laboratory (NREL) is the primary government-run lab for renewable energy testing.
This may be considered a “soft” measure of quality that is important for some buyers. The current trend in solar panels is towards less visible panels, including black backing (sometimes called black-on-black panels). The future is likely to include various styles of solar roof tiles, which Tesla has introduced on a limited basis but which are still not yet being produced commercially at scale.
Another quality measure relates to the manufacturer’s commitment to responsibility in their products, operations, and impact on other stakeholders. The best solar panels have a minimal impact on the environment both during the manufacturing process and at the end of their lifecycle. There are several organizations that provide benchmarks on sustainability in the solar PV supply chain. The Cradle to Cradle Certified™ designation assesses products including solar panels for safety to human & environmental health, design for future use cycles, and sustainable manufacturing. The Silicon Valley Toxics Coalition (SVTC) produces a biannual Solar Scorecard that assesses solar manufacturers using sustainability and social justice benchmarks. It is also possible for solar panels to participate on the Declare label platform, which provides transparency into a product’s origins, ingredients, and end of life options such as recycling.
Top Solar Panel Manufacturers
There are several websites that provide unbiased assessments of the best solar panels for leading manufacturers in the U.S. and worldwide.
After reviewing the detailed technical specifications for thousands of panels, EnergySage rates the top 46 manufacturers according to efficiency, temperature coefficient range (which measures the loss in power output as the temperature rises), and warranty. According to their analysis, the top manufacturers are:
- Efficiency: SunPower, Panasonic, LG, and Solartech Universal (all greater than 20% for their most efficient panels)
- Temperature coefficient: Stion, Silevo, Panasonic, and SunPower (all below -0.3%/degree Celsius)
- Warranty: SunPower, Panasonic, and Solaria (all 25 years)
The expert rating on SolarReviews indicates that Panasonic, LG, Canadian Solar, SunPower, and Hyundai Heavy Industries are the top 5 manufacturers who make the best solar panels.
Tips for Shopping Solar
Know what solar panels you’re getting
It is important to ask your local solar company which brand of solar panels they will be installing on your home. Don’t be afraid to request details on the manufacturer, make and model, and warranties associated with each component of your system from the panels to the inverter.
Don’t take their word for it
Seek out independent analyses or tests comparing the performance and durability of solar panels.
Trust your gut
At the end of the day, the best solar panels are the ones that fit your needs. Everyone has a different threshold for cost and quality, as well as different time horizons for evaluating the financial return of solar panels.