How We Found the Best Solar Panels
We focused just on residential solar arrays (also called solar photovoltaic or PV systems), and went big and broad to start, compiling a long list of panel models from major vendors and industry reviews. From there, we weeded out any solar panel not currently in production: While discontinued panels may seem like a steal, engineer and professor Dr. Tom Lombardo confirms that “the first thing not to focus on is the price. Buying the least expensive panels may result in lower quality, and if the company goes out of business, the warranty is useless.” With that in mind, we also eliminated solar panels from companies that were defunct, seeking bankruptcy protection, up for sale, or otherwise financially unstable, leaving us with 188 panels.
We cut companies that haven’t been around for at least 10 years.
According to Green Tech Media, the solar panel (for example: GOAL ZERO NOMAD 7 ) industry is volatile, with a whopping 88 companies bankrupting between 2009 and 2015. The rate is beginning to slow, but a glut in the marketplace around 2011 so drastically lowered the prices of panels that manufacturers were (and some still are) having a hard time making a profit. The MIT Technology Review says these failing companies are better for the solar industry overall — a more competitive market with bigger profits is key in investing in new equipment and driving technology forward — but bad news for your warranty.
There are two standard warranties for solar panels: a 25-year performance warranty guaranteeing certain levels of electricity production, and a 10-year workmanship warranty covering the panel hardware, like the diodes and glass. And Lombardo notes that panels can often last well beyond 25 years. If the company that made your panels goes belly up, your warranties are void — and there goes your $40,000 investment. For our top picks, we chose companies with staying power. Newcomers: It’s up to you to prove us wrong.
We required at least 230 watts of power.
Watts measure the “electricity production top speed” of a solar panel, or put simply, how much power each one can generate. Wattage helps determine how many panels to install: Take the full wattage that it takes to power your home and divide that by each panel’s wattage. If the average US home usage is 5,500w and you’re looking at, say, 300w panels, you’ll end up needing 19.
But remember! You also have to take into account the total surface area of your roof that is good for solar: the part that has the right angle to the sun, southern or western exposure, and little to no shade. If you have a 1,200-square-foot home and assume around 40 percent is good for solar, that’s only 480 square feet. Panels are, on average, 18.3 square feet and if you need 19 to power your home, you will use nearly 350 square feet of that space.
Take a lower-wattage panel though, say 175w, and you’ll need almost twice as many panels to create the same amount of electricity — and therefore twice as much roof space. You can solve the space problem by getting more smaller lower-watt panels, but then you’re increasing your installation costs.
The long and the short of it: You want fewer, higher-wattage panels. Because wattage is directly related to a panel’s dimensions, 230w is by no means a hard-and-fast cutoff. Most solar panels average right around 200w (and the average on our list was 265w) so we skewed our picks to be the best. That said, if you have your heart set on a daintier solar panel that only outputs 200w, it could still be a great choice.
The manufacturer’s customer service had to be top-notch.
In a perfect world, you wouldn’t ever really talk to your solar panel manufacturer. Purchasing, setting up, and repairing your solar array are funneled through your installer — similarly, you wouldn’t contact whoever made your shingles if your roof started leaking. All solar manufacturers have preferred installers; likewise, all installers use panels from their manufacturing partners. (You get to choose which path to go down: starting with the panel and then getting set up with their installer in your area, or picking an installer and then choosing from its preferred panels.)
In the event your installer goes out of business, though, contacting the panel manufacturer is the only way you’ll be able to leverage your warranty if and when you need to. We want to recommend solar panels from companies with amazing customer service that can answer your questions and (if necessary) assist you in a jam.
We evaluated our remaining contenders on the quality of their websites — was it easy to locate basic information like warranty and company history? — as well as their telephone and email service. (Panasonic didn’t return our phone calls or emails for over a week.) Five companies stood out as the best, and their panels made it into our top picks.