Some solar companies say the type of panels on your roof doesn’t matter because you are only buying the energy they produce. But when you’re making such an important investment in your home — whether you lease your solar system or buy it — quality and performance are still important.
Efficiency is an important measurement of solar panel performance. Efficiency measures the amount of our sun’s energy (photons) that can be turned into electricity (electrons) within a given area; in this case, your roof. Higher efficiency means more energy can be generated in less space, and more energy can mean greater savings and fewer panels on your roof, which can help your home retain its curb appeal. It’s also important to consider the quality of the panels and the manufacturer’s warranty — because the longer they last, the more savings you’ll see over time.
Types of Solar Panels
Almost all home solar panels are made using crystalline silicon. You might be familiar with silicon because it’s used inside the microprocessors of computers, cell phones and other electronics. Silicon conducts electricity, which makes it perfect for these devices and for solar panels.
There are two types of solar panels: monocrystalline panels and polycrystalline panels. The main difference is the purity of the silicon. Monocrystalline silicon is made from a single-crystal, and polycrystalline panels are made by melting silicon fragments together. In monocrystalline panels, the electrons have more room to move around, thus are “more efficient” or better at turning sunlight into electricity.
Monocrystalline has the highest efficiency ratings among panels available to homeowners today, from 15 to more than 22 percent. SunPower produces the highest efficiency monocrystalline solar panels. Our X22 has a record-breaking efficiency of up to 22.8 percent, making it the best performing panel available on the market today.1 Polycrystalline panel efficiency typically ranges from 15 to 17 percent.
Panel Quality and Warranty
When you buy a refrigerator, you expect it to maintain its cooling temperature for many years. You don’t expect it to show wear after the first year and become a few degrees warmer every year. That’s essentially what happens to solar panels on a rooftop. Weather and temperature fluctuations can cause panels to degrade over time and produce less energy. Most solar panels lose about 1 percent of their power generating capacity per year.
SunPower® solar panels are made with Maxeon® solar cells that are built to withstand these tough conditions. Their patented solar cell design degrades just .25 percent per year. At the end of 25 years, conventional solar panels have lost 25 percent of energy production while our panels with Maxeon technology have lost only 6.25 percent. That means SunPower panels generate up to 70 percent more energy in the same space over 25 years, giving you the greatest savings over time.2
A solar company’s product warranty is an indicator of how much a company is willing to stand behind its products. SunPower offers an industry-leading 25-year Combined Power and Product warranty. In the unlikely event that a SunPower panel is underperforming, we will repair or replace the panel and reinstall it on your home.
There are many important factors when going solar, and performance, quality and warranty are at the top of the list. You also want to make sure you purchase the panels from a reputable company that will be around to back up its warranty. SunPower has a 30-year track record of leading solar innovation, and we design and manufacture our own products.
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1 Green, M. A., et. al. “Solar Cell Efficiency Tables (version 47),” Progress in Photovoltaics, 2015
2 SunPower 345W compared to a Conventional Panel (250W, 15.3% efficient, approx. 1.6 m2), 9% more energy per watt, 0.75%/yr slower degradation. BEW/DNV Engineering "SunPower Yield Report," 2013 with CFV Solar Test Lab Report #12063, temp. coef. calculation. Campeau, Z. et al. "SunPower Module Degradation Rate," SunPower white paper, 2013. See www.sunpowercorp.com/facts for details.