Yes, some panels are more efficient than others, but that doesn’t mean that they are worth the additional cost.
Many people ask, “Which solar panel should I choose? Which panels are the best?” Though any salesman is going to tell you his panels are the best, the truth is that it is not easy to compare solar power panels and to firmly state that one brand stands out among the rest as the best.
The solar panel comparison chart I created below shows how difficult it can be to compare panels and brands. Listed are common panels between 190 and 230 watts of 5 common solar panel manufacturers (Canadian Solar, Kyocera, Sharp, SunPower, and Suntech).
At first glance you can see that there isn’t even a standard DC watt rating. 200, 210, 220 etc. seems obvious, but then there’s 205, 208, 216, 225. What does all this mean?! It simply means that the panels produce at slightly different outputs.
I’ve attempted to standardize the comparison by including “Cost per Watt” and “PTC Watts per Sqft”. I’ve also included “True” factors, which simply means numbers based in reality as opposed to theory. Though a panel may have high efficiency, you can’t use 5.65 panels; you have to put 5 or 6 panels on your roof. And the sqft of 6 panels is going to be more than that of 5.65 panels.
(Red means bottom 5 of the category and Green means Top 5 of the category).
(Click on the chart to view larger image.)
As you can see on the chart, some panels are top 5 in some categories and bottom 5 in others. No specific panel is top 5 all the way across. It looks like SunPower solar panels score high in several categories, but does that mean they are worth the extra money? Maybe not, actually. The difference between a less efficient Kyocera, and a more efficient SunPower panel is negligible in terms of performance. You might get an extra $3 of energy per year for the same system.
Though hopefully helpful, the chart still doesn’t include other factors such as the environmental efficiency of the manufacturing process of the panels, how “green” the company is, or how the panels look.
So, how does one decide which solar panel to use? As a consumer, make sure the panel has at least a 25 year warranty and then let the installer make the decision.
The two most important numbers in comparing solar PV systems are 1) the AC kWh output/year, and 2) the cost. Whichever complete system can give you the most yearly output at the best price is the system to choose. Read that again.
When you are comparing panels or installation proposals, make sure the panels are warrantied for 25 years, the inverter for 10, and the installer warranties his work for at least 5 years. Then compare the yearly kWh output (in AC) and the price. All other factors equal, the most bang for the buck is the best deal.
Ultimately, the most important thing is to install solar! The difference between using non-renewable coal, gas and nuclear energy and using renewable solar, wind, and geo-thermal is the one thing everyone should be comparing!
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- DC = direct current
- PTC = PVUSA Test Conditions (realistic test conditions)
- sqft = square feet
- True = real world
- True # of panels = the rounded number of panels it would take to get closest to a 1 kW array. (1,000 / PTC rating, then rounded to the nearest whole panel)
- Cost per DC and PTC may vary. Numbers given are general estimates and vary depending on many factors.