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 »
Step 1: Determine your solar array size in kW and enter it into the calculator below.
Step 2: Decide which solar panels you want to use, and enter the DC Watt rating of the specific solar panel model you want to use into the calculator below.
This is an edited excerpt of an article originally posted on AOL Real Estate written by Audrey Tempelsman. Audrey asked me to help her on an article you can read in full here.
There are a nerve-wracking number of solar manufacturers and installers out there, so I caught up with Shawn Roe of SRoeCo Solar, a solar advice service, and asked him to share five questions that all consumers should ask before purchasing a system. I hope you’ll find his insight as helpful as I did:
1. “How many systems has your company installed?”
Due to the recent spike in solar panel installations, and the decrease in other construction-related businesses, many roofers, fencers, and builders are attempting to start solar installation companies with no solar experience and without proper solar installation knowledge. Look for a reputable installer with at least 50 installations and a few references. Read the rest of this entry »
Should I use Sanyo 200′s or Suntech 270′s? SunPower 210′s or Canadian Solar 240′s? Which size solar panel you use depends mainly on how much roof space you have available and how much electricity you plan to use (with solar power). Below are 6 steps to calculate which size solar panels you need for your building.
Step 1: Know Your Electricity Usage
Gather your old electricity bills for the past 12 months. Contact your utility company if you don’t have them and your electricity provider should gladly send you a printout with your past electricity usage. You’re looking for 2 things: (1) your monthly kW/h usage, and (2) your monthly cost.
Step 2: Know your Roof Direction
Grab a compass (maybe your car navigation, or check Google Maps) and figure out which way is South. Go outside, look at your roof and see how much roof space is facing South, Southwest, East and West. The more South the better, but West is actually okay.
Step 3: Measure Roof Area Read the rest of this entry »
*UPDATE – Check out SRoeCo’s sortable, searchable Solar Panel Comparison Table.
This is a chart of the “Top 40 Most Efficient Solar Panels” available on the market today (11/01/09). All 40 most-efficient solar panels are from 2 companies: SunPower and Sanyo Electric. If you have limited space on your roof and budget is not a concern – these are the best solar panels on the market giving you the highest efficiency (greatest output) per area.
All of these solar modules are Monocrystalline clearly proving that this type of solar panel is the most efficient – more efficient than Polycrystalline and Thin Film. The panels listed at 290 kW and above all take up more than 17.5 square feet per panel. The solar panels rated at 230 kW and below take up less than 13.5 square feet. Read the rest of this entry »
