Two great questions many people ask about solar panels are: “Which panels have the highest efficiency?” and, “Which solar PV panels are the best?”
This solar power panel comparison chart below compares the density and module efficiency of the most popular 200 W solar panels. All of the modules on this chart are label rated at 200 Watts, which means in strict laboratory conditions, they produce the same output. However, I have compared them based on their PTC ratings which is the rating given under realistic test conditions. Sanyo, SunPower, Canadian Solar, Suntech, Trina, Kyocera, Schuco, BP, Yingli and Sharp are common solar panel manufacturers used by installers in the US.
(Updated 5.19.2012 – Read more about the Tier rating system here.)
Of the highest output panels, both Sanyo and SunPower panels have the highest efficiency per surface area in real world conditions. Given a limited roof area with which to install solar panels, these panels are the best choice to produce the most electric output per square foot. However, this doesn’t mean that these panels will always be the best choice. Well, how should you choose solar panels then? Here are 5 questions to ask your installer before going solar.
The chart below shows some of the most common and efficient solar power panels (rated at 220 W) on the market and listed on the State of California’s “List of Eligible SB1 Guidelines Compliant Photovoltaic Modules” as of May 19, 2012.
I’ve even included Solyndra’s 220W module, which you can see has the worst efficiency per area of all the panels because it’s not crystalline, but thin-film. Yes, thin-film is significantly less efficient than crystalline (mono and poly) panels.
So, if I know the most efficient solar panels, then I know which solar panels are the best, right? Well, if efficiency is all you care about, then yes. But efficiency may not be the most important factor.
You might have noticed that the Schuco Tier 2 panel has higher efficiency, but is ranked lower than Suntech Tier 3 panel. That’s because the chart is sorted based on density (read the basics to understand the difference between density and efficiency). This means your installer will sell you on the fact that the Schuco is ‘more efficient’, even though the Suntech will give you more solar power per area. Don’t worry, there’s a better way to compare panels. I believe that the two most important factors in choosing the best solar panels are 1) the annual kWh production (the expected output) and 2) the price.
So, you know which are the most efficient common panels. But, which are the most efficient of them all? Continue to the solar panel comparison table.
Manufacturer = Solar Company; Brand
ID = Specific solar module identification code; module name
STC (W) = Standard Testing Conditions Rating; nameplate rating under laboratory conditions
Density (W) = Efficiency per area; realistic output per area, the higher the more output in a given area
Efficiency (%) = Output per input light irradiance using STC; energy conversion efficiency; module efficiency
Tier = Solar Panel Efficiency Tier. 1 is highest, 5 is lowest