Friday, April 30, 2010

First Full Month of Solar

As April ends, I can now assess the results of our first full month of having solar power. Specifically, I was very interested to see if my projections for solar production were even close. If you remember, I wrote this blog entry back in October 2009 as I was trying to determine how big a system to get, what sort of output I could expect and what my savings would be. I created this Google Docs spreadsheet to help with all these calculations.

For the month of April, the spreadsheet predicted for the 3.68kW system we got, production of 513 kWH (this actually comes from the PVWatt tool mentioned in the spreadsheet). It didn't look like we'd get there as the 27th and 28th were overcast and rainy days, but the last 2 days of April turned in the highest production so far. Actual production came in at 538 kWH. Based on this, it looks like the analysis I did in the spreadsheet turned out very accurate and as a result, I'm very pleased with our purchase so far.


  1. Hi,
    How much do pay per kWh?
    What is your estimated yearly production?
    How much was the investment?
    How many years to break even?

    I'm happy for having that much sun. In my region, people are also talking a lot about solar power but I question the total finanzing

    Best regards, Walter

  2. hi,

    the answers to all your questions are in the spreadsheet linked above. i wrote that spreadsheet to help with my purchasing and sizing decisions.

  3. Oops, thanks
    What do you estimate? Nbr of years for your investment to be paid off?
    Her where I live in Sweden, heat pumps are very popular. The one I'm considering is about $12k and gives 6kW. But if a lot of expensive repairs happen, the total financing crashes. There solar seems superior, not much maintenance I guess

    Bes regards, Walter

  4. there's a breakeven graph on the spreadsheet. assuming our usage doesn't go up (it definitely will, however, as we buy more gadgets and maybe an electric car at some point), breakeven will occur somewhere around 8.5 years.