Clean Power

Published on October 11th, 2013 | by Zachary Shahan


Cracking The Code Of Residential Solar Power

October 11th, 2013 by  


SmartPower, which is reportedly “the nation’s leading non-profit organization for energy efficiency and clean energy,” recently embarked on a 20-week pilot program aimed at encouraging more people to put solar panels on their roofs. The result was apparently quite an increase in people going solar. So, let’s have a look at what the organization did, and the specific results.

To start with, residents were offered the option of buying solar power through SmartPower’s Solarize program, which resulted in them saving about $7,500 on average compared to current market averages.

Well, yes, $7,500 in savings is going to attract customers! Compared to the average solar adoption rate from the previous 7 years, the rate of solar power purchases in the participating communities was 24 to 64 times higher. Of course, with solar costs coming down tremendously in recent years, a lot more people should be going solar anyway, but a 24- to 64-time increase still must be well above what would be expected otherwise.

One other important note on the results is that approximately 20% of the people who bought solar through the program said that they had never previously considered purchasing solar power.

So, with all that said, how exactly does the Solarize project work?

For one, the program offers “tiered group buying discounts.” The more people who sign up to go solar, the further the price of going solar drops.

Furthermore, participating towns and volunteers engaged in outreach to inform people about the program.

On the supplier side of the equation, the program partnered with solar installers who went solar through a competitive selection process (and used pre-approved equipment). Facilitating more competition surely helped to cut back on the considerable “soft costs” of going solar, which are much higher in the US than in Germany or other more mature solar markets.

One more important component of the program is that the solar discounts had an end date designated. Obviously, this is an effective way to motivate action — look at how many stores and manufacturers offer sales with a clear end date on the horizon.

Nothing here is particularly complicated, yet I haven’t previously seen a program so aggressively focused on reducing the costs of going solar for specific communities. Highly replicable with excellent results, I’d love to see this type of program implemented across the US and in other countries, as well.

For more, check out the full report, and let us know if you have any questions you’d like us to pass along to Brian F. Keane, President of SmartPower.

Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

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About the Author

is tryin' to help society help itself (and other species) with the power of the typed word. He spends most of his time here on CleanTechnica as its director and chief editor, but he's also the president of Important Media and the director/founder of EV Obsession, Solar Love, and Bikocity. Zach is recognized globally as a solar energy, electric car, and energy storage expert. Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in.

  • shortysears

    For a 5kw residential on-grid solar power system, I have some questions:


    (1) What is the solar collection dimensions of each individual panel, length by width?

    (2) What is the DC output power of each individual panel, in watts (clear sky, sun directly overhead [on normal to panel])?

    (3) What is the matching impedance (in ohms) to collect the maximum DC output power of an individual panel?

    (4) What is the DC output of an individual panel into its matched impedance, in volts and milliamps (clear sky, sun directly overhead [on normal to panel])?

    (5) Does the solar panel power output degrade with high ambient air temperatue (ie: in hot weather)? If so, how much?

    (6) How does the DC output power, voltage, and current vary for a solar angle off of the normal to an individual solar panel (clear sky, value vs. angle 0 to 90 degrees)? Does the optimum matching impedance vary with the off of normal angle?

    (7) What is the nominal DC input voltage to your AC power converter (inverter)?

    (8) Is more than one panel in series necessary to provide the DC input to your AC power converter? If so, how many?

    (9) What percent of the DC output power of the solar panels is transferred into 60 cycle 240 VAC single phase power by your converter?

    (10) When the sun is down (at night) does your power converter use any AC power to keep it in “stand by” mode? If so, how much?

    (11) When the “meter runs backwards”, how does the power company (Southern California Edison) “credit” the customer for this power? Is the power company required by law to provide this “credit”, or is it voluntary (and therefore revocable by them in the future)?

    (12) What is the cost of an individual solar panel (un-installed, still in packaging)?

    (13) What is the cost of your DC to AC converter (un-installed, still in packaging)?

    (14) What is the expected life span of a solar panel, in years?

    (15) What is the expected life span of your DC to AC power converter, in years?

    (16) What is the warranty on your solar panel? Does the warranty cover weather damage (hail, sleet, wind, sand storms, sub. freezing temps., ice damage, etc.)?

    (17) What is the warranty on your DC to AC power converter?

    Jim (e-mail:

    • Bob_Wallace

      You’re asking a lot of questions with multiple answers. Panel size, wattage, inverter efficiency, etc. are going to vary from manufacturer to manufacturer and from model to model.

      I’ll try to answer the ones that aren’t model/manufacturer specific.

      7-8) It can very from 12, 24, 48, 96 volts and some installations use voltages in the 100s of volts. Higher voltages allow the use of smaller gauge wire. If you start with 12 volt panels then you wire them in series to get a higher voltage.

      9) Inverters are pretty efficient. I think most are around 98% these days.

      11) Check the utility site. It varies.

      14) We don’t know. The oldest installed solar panels are now about 40 years old and are producing about 80% as much power as when new. A 0.5% (or less) output loss per year is reported from several sources.

      A 30 year study of a large array of panels found the 0.5% loss and during the 30 years about 2% of panels failed due to delaminating and connector failure. My guess is that over that 30 years we’ve learned how to build panels better so the 2% loss might not be repeated.

      That said, there have been some manufacturers who have produced some inferior panels. There are now a couple of independent agencies that certify quality.

      The other questions, you’re going to have to look at specs. Here’s a site that has excellent prices and a good reputation. (Do your own due diligence.)

      Here’s a company with whom I’ve done a fair amount of business and they’ve treated me well.

  • rarnedsoum

    This sounds like an advertorial for One Block or similar.

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