Stop searching for the ‘best’ or ‘most efficient’ solar panels. Stop trying to compare brands. The solar panels don’t matter. Obviously they matter in terms of the solar pv system as a whole, but which panels you use, isn’t important. Let me explain.
1. All solar panels are warrantied for 20-25 years, which means the manufacturer guarantees the panels will still be producing at least 80% output 25 years from now. It’s the same for all brands. Don’t believe me? Ask the guy selling them.
Want to know how to choose the best solar panels? It’s not too difficult: simply find out which ones give you the most electricity for the cheapest price. Let’s call this ‘solar value’. The lowest price per kwh can help you find the best solar panels.
Well, how do you figure out which panels give you the most electricity? Do I need to know which panels are the ‘most efficient’? Nope – actually you don’t. Efficiency is not the same as output. Efficiency is output per area. If you’re strictly looking for the solar panels with the best value, then you only need to care about the output. Let your installer worry about the area.
So, you’ve got a few quotes from solar installers and want to know which solar power system will give you more energy / output / electricity. Let me teach you how to calculate solar output like the pro’s. This way you can double-check their quotes to know you’re getting a good deal.
Step 1: Grab your solar quotes and look for the specific solar module name and how many solar modules will be installed. Make sure you know the exact panel. Circle the panels and how many. Ex. 20 x SunPower SPR-200-BLK-U.
Then find the exact solar inverter in the estimate. This might be SMA SunnyBoy, Xantrax, Fronius, or Enphase. Circle this too. Ex. SMA SB4000US (240V).
One great thing about the California Solar Initiative (CSI) is that they keep pretty good data on the solar in their state. Thankfully it’s the US State with the most solar installations (4 times as much as 2nd place, NJ). So we can use CA’s data to find out which solar panel brand is the most popular.
The two most popular are SunPower and Sharp. Then, there’s a big drop off to Kyocera and Suntech. You won’t see BP’s number get any higher as the company has decided to shut down it’s solar division.
So, now that we know which solar panel brands are being installed the most, let’s see how difficult it can be to compare solar panels.
To simplify solar efficiency further, we have divided all modules into 5 tiers based on their efficiency compared to all other solar panels. Now installers and consumers can easily communicate about module efficiency. Are the solar panels in the most efficient tier (Tier 1) or do they have average efficiency (Tier 3)? If modules are in the least efficient tier (Tier 5), let’s hope they’re cheaper than the modules in the above-average tier (Tier 2).
How much do solar panels decrease over time? The solar industry standard is a conservative estimate of 3% in the first year, and less than 1% per year after that. However, solar panel manufacturers are starting to realize that this is too conservative, and they are beginning to warranty their panels to more realistic degradation rates.
There are three points I want to make.
Use the solar panel’s warranty to compare output loss over time because that is the only output you are guaranteed.
Realistically expect less than a 3% decrease in output the first year, and about .5% decrease per year after that for most panels.
One solar panel from 1979 was tested in 2010 (after 30 years) and its output was better than the original factory specs.
This is an infographic put out by 1Bog Solar explaining why solar works (well) in your state even if you think it doesn’t. Right click and choose “View Image” to view full size. Clicking on the image will take you to 1Bog Solar which is a group solar purchasing organizer. Think of them as the Groupon of Solar (before Groupon).
Yes, I recommend signing up with them, even if you don’t go solar with them.
Occasionally, people ask me how to choose the best solar pv system, or the best panels. Choosing the best solar system depends mainly on your energy needs, roof space, and budget. Most people really want to know how to choose the best solar value. For example, I was asked the following question on my “Help me help you” survey:
I got bid from 2 different installers. One was SunPower panels; the other Canadian Solar. The SunPower bid (for a 5.2 kw DC system) was $21,000 and the Canadian Solar bid was $14,000 – why so far apart?
Great question. There could be many explanations why there is such a gap in the price. Generally, SunPower’s superior efficiency allows for it/ necessitates that it price its solar panels higher. (They have to pay for the best engineers to get the best efficiency, right?) Each installer may be giving you the best deal he can with both brands of panels. What you should check on both proposals is not the DC system size (in this case 5.2 kw DC), but the kilowatt-hours output. Ask your installer(s) how much energy (in kwh) each system expects to produce in the first year.