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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.
Solar panel efficiency is simple, but there a few things you need to understand.
There are 3 main types of solar efficiency.
1. Module Efficiency
2. Area Efficiency (Density)
3. Cell Efficiency
1. Module efficiency measures how well a solar module (aka panel) converts the Sun’s energy into usable energy. If the Sun dumps 100 Watts of energy onto the module and the module spits out 15 Watts, the the module is said to have 15% module efficiency (15 W / 100 W = 0.15 = 15%). If you want to brag to your friends that you have a top tier efficiency panel, care about this. Read the rest of this entry »
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.
Here are links to solar panel manufacturer warranty documents. Please contact us if you would like to contribute more! Thanks! Hope this is helpful.
Brad had a very good question that I thought needed to be explained in a post of it’s own.
I’m confused as to how a less efficient system (measured under PTC) could output more.
The simple answer is – if there are more of the ‘less efficient’ panels.
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.
My prospective supplier states that the Schuco 210 watt SMAU-1 panel has a cell efficiency of 16.8%, whereas your table gives a panel efficiency of 12.43%. What is the difference between panel and cell efficiency and which should be my guide?
Great question.
Confusing chart of solar cell efficiencies
Cell efficiency is measured as the percentage output of energy to the theoretical amount of energy supplied by the Sun (hitting the cell). So if 100 Watts hits the cell (under Standard Testing Conditions, STC, which is laboratory conditions), and it spits out 16.8 Watts, then the cell efficiency is 16.8%.
My table gives panel efficiency of how much output of energy (as measured by PTC, which is the realistic test conditions of a panel on a roof) to the amount of space that panel takes up in squarefoot area.
Your supplier is right, but if you want a point of comparison, ask him to give you the “cell efficiency” of all the competitor’s panels. What my table allows you to do, is compare all the panels (eligible for rebates in CA, which is more than 1,700) by the panel efficiency. Though our efficiency measurements are slightly different, mine are standardized across all panels using the data that CSI (California Solar Initiative) uses to pay rebates. So, you can easily see how Schuco 210′s compare to any other 210 panels (or 200, or 220, etc…)
Hope that answers your question. He’s not lying. I’m just giving you more information.
Good news for solar, but bad news for future customers: the solar incentives for two of California’s biggest electric utilities have decreased by 40%.
The good news is that Pacific Gas and Electric (PG&E) and San Diego Gas and Electric (SDG&E) have received enough California Solar Initiative (CSI) applications to install solar that they have reached the maximum amount for Step 6 in the incentive scale. Current and future applications to install solar for customers of these two utilities will be eligible for the Step 7 incentive rate of $0.65/watt DC.
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. Read the rest of this entry »
Suntech - 2011
