Annual Solar Update – 2014

As of the beginning of October, it has now been a full year since our first solar array came online. I decided that it would be appropriate to start writing annual reports for our solar array, and this seems like a good time to start!

Monthly Solar Production vs Predicted for Phase 1's First Year
Monthly Solar Production vs Predicted for Phase 1’s First Year

The original 6.0 kW array first came online on the morning of October 4th, 2013. At that time, my predictions using the then-latest software from the National Renewable Energy Laboratory, indicated that we would produce 6,759 kWh in an average year. Since then the NREL has released new software which updated this prediction to 7,299 kWh. However, our actual production on the original array for October 4, 2013 through October 3, 2014, was 7,493 kWh, which is higher than both predictions, and also far higher than our installer’s predictions.

Phase 2 Production vs Predicted through October 2014
Phase 2 Production vs Predicted through October 2014

The second array, rated at 6.2 kW, came online on March 26th, 2014. Through October 3rd, it had produced 5,784 kWh. For comparison, during the same time period the first array produced 5,439 kWh.

Monthly Predicted vs Actual Total Solar Production
Monthly Predicted vs Actual Total Solar Production

Comparing this to the month-by-month predictions from the NREL, this puts us at about 101% of predicted overall. Over this same time period, since both arrays have been online, we have used about 3,800 kWh less than we produced. This gives us a nice bank of power to start consuming as the days get cooler and we run the heat pump more and more, and the sun is out less and less. So overall, things are going well!

If any interesting solar-related events happen over the next year, I will post here, but otherwise I’ll post again next October with another annual update!

3 thoughts to “Annual Solar Update – 2014”

  1. Ok, your data reinforces my belief that this past Summer was one of the longest, sunniest and warmest we have had in a long while!

    Curious to how the “banking” part works. I have a local EVer who has solar and he gets checks from PSE (or State?) for power he returns to the grid AND an electric bill for his usage.

    Do you have the option to bank a portion of your production? or is it something your utility determines?

    1. You have two options for your billing with PSE. One is to use net metering, where your excess production subtracts from your usage and if you produce more in a month than you use, it banks and carries over to future months (but gets reset to 0 at the end of April).

      The second option, potentially useful for those who have extremely large arrays and don’t use nearly as much as they produce, is to have your solar connected to the grid by itself essentially as a power plant. Then PSE will pay you for every kWh you produce, but the rate is relatively low.

      In either case you could get the state’s production credit (via PSE).

      However I question whether your local EVer is either misunderstanding himself what his check is for, or he is miscommunicating it, as it usually not logical for a residence to connect in the latter method.

  2. Thanks for the clarification. I am guessing its my memory that is confused. This was a conversation from several years ago (he has been driving NEVs for almost 10 years now (The benefit of living and working in the same town!) and was one of the first persons I know of to get Solar.

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