How to Compare Solar Panel Brands

Once quotes start arriving, the panel brand is often the first thing homeowners look up. It's a natural place to start, and it's easy to go down a rabbit hole of rankings and reviews.

This article shows what actually separates one panel from another and how to compare them on your own quotes. For how the whole system fits together, start with our guide to how home solar works.

Is there a single best solar panel brand?

No. Panels installed on U.S. homes have to pass the same required safety testing, and the gaps between established manufacturers are often smaller than rankings make them look. The right panel depends on your roof, your energy use and the warranty behind it.

What differs is the specific model. One manufacturer may sell several panel lines with different wattage, efficiency and warranty terms. So a fair comparison is model to model, not brand to brand. Ask every company for the exact model number on its quote, plus the datasheet and the warranty document for that model.

Then compare the panels the way you'd compare anything you plan to own for decades: what it does, how it holds up, and who stands behind it.

What should you compare between solar panels?

These are the details worth lining up on every quote. Most come straight off the datasheet.

You don't need to become an expert in any of these. You just need the same facts from every company, so you're comparing like with like. Our guide to comparing solar quotes shows where the panels fit among everything else on a quote.

How do wattage, efficiency and heat affect your choice?

Wattage is how much power a panel is rated to make under standard test conditions. A higher-wattage panel makes more each, so a system of the same size needs fewer of them. That helps on a smaller roof or one broken up by vents, dormers and chimneys.

Efficiency is the share of the sunlight hitting a panel that it turns into electricity. It matters most when roof space is tight. On a roof with plenty of good space, a slightly less efficient panel can do the same job, so don't pay extra for efficiency your roof doesn't need.

Temperature coefficient is the spec most people skip. The Department of Energy notes that solar cells generally work best at low temperatures, and much of the sunlight that hits a panel turns into heat. As a panel warms up, its output drops a little. The datasheet lists that drop as a percentage per degree. A number closer to zero means the panel loses less power on a hot summer afternoon.

None of these specs tells you how much a whole system will produce on your roof. That depends on the design, which is why Evergreen Solar's engineering team works it out for each home in its own design software.

What do solar panel warranties cover?

Most panels come with two separate warranties, and it's worth reading both.

• The product warranty covers defects in the panel itself, such as problems with materials or how it was made.
• The performance warranty (also called a power output warranty) promises the panel will still make at least a set share of its rated output after a set number of years. Panels lose output very slowly as they age, and this warranty covers a panel that loses it faster than promised.

The two terms aren't always the same length, so check the number of years on each, and the share of output promised at the end. Then read the fine print on what a claim covers, and ask whether it includes the labor to remove and replace a panel or only the panel itself.

Inverters carry their own warranties, often on different terms. Our article on what a solar inverter does explains that part of the system.

Why does the company behind the panel matter?

A 25-year warranty is only as good as the company that has to honor it. A manufacturer with a long track record and a real presence in the U.S. market is easier to reach years from now than one that may not be around. That's why installers talk about using established, Tier 1 rated manufacturers.

Tier 1 is a label from BloombergNEF, a research firm, for panel makers whose panels banks have recently financed on large projects. It's a sign a manufacturer is established, not a quality grade, and the list changes every quarter. Treat it as a starting filter, then look at the model and the warranties.

Just as important is who handles a claim. If a panel fails, will your installer diagnose it, file the claim and swap the panel? Or will you be on the phone with the manufacturer yourself? Ask before you sign.

Check the safety listing too. U.S. electrical codes require panels to be listed by a nationally recognized testing laboratory, and new panels are evaluated to UL 61730, the U.S. version of the international panel safety standard. Many datasheets also list IEC 61215, a set of design and durability tests for panels meant for long-term outdoor use. Passing those tests is a baseline, not a prediction of how long a panel will last.

Do looks and where panels are made matter?

Looks are a fair thing to care about, since the panels will be on your roof for decades. All-black panels use a black frame and black backing, so they blend in with darker shingles. Others show white lines between the cells or a silver frame. Ask to see a photo of the exact model.

Where panels are made can matter too, mostly for leases and PPAs. American-made equipment can help a system qualify for an extra federal bonus, which can mean a better rate for you. Ask whether the panels on your quote affect the price or the rate. Our article on solar leases vs. PPAs explains how those options work.

Why does the installation matter more than the brand?

A good panel can't make up for a poor design or a sloppy install. Where the panels sit on the roof, how shade is handled, which inverters are used and how carefully the roof is sealed all affect how much power you get and how the system holds up.

The inverter choice is a good example. With microinverters, each panel works on its own, so one shaded panel doesn't drag down the rest. Our comparison of micro-inverters and string inverters explains the trade-offs.

The same goes for the roof work. Racking that's attached to the rafters and flashed properly keeps water out for decades, no matter whose name is on the panels. Ask every company how it mounts the panels and seals the roof, and who comes back if a leak ever shows up.

Our guide on how to choose a solar installer covers what to look for in the company itself. Want to see which panels would fit your roof? Call us at (508) 507-2908, and we'll walk you through the exact model, its datasheet and both warranties.

Frequently asked questions