Determining who makes the best solar panels can be challenging, especially with the proliferation of solar companies over recent years.
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.
EVALUATION CRITERIA
You can use several criteria to evaluate the quality of solar panels:
Efficiency and yield
Warranty
Durability
Aesthetics
Sustainability
EFFICIENCY AND YIELD
Polycrystalline vs Monocrystalline Solar Panel Solar Cell Type
Efficiency refers to the amount of power produced at peak daylight as sunlight is absorbed. For example, if a solar panel is rated at 20% efficiency, then 20% of the sun’s energy that hits the panel will convert to solar energy to use for power electricity.
Yield, on the other hand, is determined by:
High-temperature performance
Spectral response (i.e., the ability to capture energy from reshifted sunlight in the morning and evening)
The use of 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)
Shade performance
The primary determinant of solar panel efficiency is the materials used in the panels. The most efficient material is monocrystalline silicon.
Other materials also make a difference, including a panel’s conductive metal foundation, the type of glass used on the front of the panel, and the interconnects between the cells. Thin lines of metal ribbon on the front of a cell indicate that a panel is at increased risk of breakage compared to those with a copper-backed foundation.
Most standard efficiency solar panels range from an average of 15% to 20% efficiency. The largest global manufacturers of standard efficiency panels include Trina Solar, JinkoSolar, and Canadian Solar. U.S.-made solar standard efficiency panels are available from Mission Solar.
Commercially available high-efficiency solar panels range from 18% to 22%. Solar companies who make high-efficiency panels include SunPower, LG, REC, Panasonic, and Silfab Solar. Some SunPower panels have been rated as high as 24%.
However, there are limits to the maximum potential efficiency of solar cells. Solar radiation in different parts of the country, roof pitch, azimuth (horizon angle), the direction your panels face, and temperature all affect solar panel efficiency. Additional energy loss may also be associated with the length and type of the cabling, voltage limits, and inverter efficiency.
These related performance measures have a direct impact on how much power your system will produce per watt installed. Making sure you have the most recent energy efficiency information will afford you the highest return on your investment over the lifetime of your solar panels.
[Related: Where to Install Solar Panels]
WARRANTY
The expected lifetime of equipment and the length of time a company will guarantee its performance are correlated. Here are three considerations to keep in mind when evaluating a solar manufacturer’s warranty:
Equipment: Ask about the warranty coverage for performance and materials. Make sure you understand if there are different guarantees on the inverter, monitoring, and other equipment in addition to the panels.
Process: Ask about the warranty services provided. Be sure to understand the required steps to file a claim and 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. Make sure you’re confident that the manufacturer will be around for the duration of your warranty period.
[Related: What to Expect: Your HOA and Solar Panels]
DURABILITY
A solar panel’s durability is another indicator of its quality. Several reputable third-party organizations independently test solar panels. Their ratings will give you an idea of how well yours will hold up in harsh conditions such as storms, hurricanes, hail, and more over time.
Fraunhofer is an applied research organization with world-renowned solar power technology expertise. They assess 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. The scorecard is based on their Product Qualification Program using independent laboratory testing of solar panel reliability across multiple manufacturers.
However, the National Renewable Energy Laboratory (NREL) is the primary government-run lab for renewable energy testing.
Keep in mind that rain, clouds, or an accumulation of debris, dirt and dust can impact your system’s energy generation. So if you’ve noticed more inclement weather days than normal over recent months or the past year, or if your panels need a thorough cleaning, it may be the cause of reduced energy production rather than any issue with the system itself.
Contact your solar installer or the solar panel manufacturer for assistance if your system is underperforming and none of the above factors are the cause.
AESTHETICS
Aesthetics are very important for some buyers, although they’re considered a “soft” measure of quality for the most part.
The current appearance trend for solar panels leans toward less visible, including black backing (also referred to as black-on-black panels). Coming years will likely see various styles of solar roof tiles, which Tesla has introduced and now sells on a commercial scale.
SUSTAINABILITY
Solar panel quality also relates to a 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 during the manufacturing process as well as at the end of their lifecycle.
Several organizations provide benchmarks on sustainability in the solar PV supply chain. The Cradle to Cradle Certified™ designation assesses products in terms of safety toward human and environmental health, design for future use cycles, and sustainable manufacturing.