DirkH asked in a comment if I’m keeping any records on the performance of the 12-kW PV system my family installed on our home last year. He thinks the German Weather Service statistics concerning the amount of sunshine in Germany for June seem a little high. First, the sun statistics from the German Weather Service DWD seem to be spot on, and agree with the production of our PV system.
The first half of June was really good – plenty of sunshine. Our system produced over 1000 kwh in the first 18 days alone, with many days producing over 60 kwh. But things got bad starting June 19. The last 10 days have been really terrible. Yesterday was the worst summer day for solar energy I’ve seen so far (only 16 kwh). This month we’ve produced 1325 kwh up to now, which is okay.
Our PV system has a data-logger, but I haven’t taken the time to get it all set up on my PC notebook etc. and so I can’t present you with all these neat graphics. I just write down the result every evening and calculate output each month.
Monthly outputs so far:
Jul 2012: 957 kwh (July 10 – 31)
Jan 2013: 114
Jun (so far) 1310
I’ve spoken to other system operators who have had them a few years, and they tell me this year overall is the worst. It’s been cloudier than usual. Overall our PV system hasn’t performed as well as I hoped. The panels only work at about 75% when it’s too warm, they rarely operate at their rated capacity, even when the sun shines directly on them.
They tell us that the system pays for itself within 9 years or so. But if the power converter breaks down and you have to replace it, then you can add another 2 years. Then there are some maintenance costs, insurance, etc. So if we’re making money after 12 years, I’ll be surprised. Then there’s also the disposal costs. I seriously doubt I’ll be able to just throw everything out along with the household rubbish.
I bought the system only because 1) the person who sold it to us is a customer of ours, and 2) I didn’t want to be forced to pay high feed-in rates to subsidize other PV operators. Unfortunately it’s a screw, or be-screwed situation. Believing that we’re doing something good for the planet is totally idiotic. The feed-in act benefits (if at all) property owners with good southern exposure. The rest get the shaft.
After almost one year of operation my assessment is: I’m a little disappointed, and expected more from it. On a scale of 1 to 7, 1 = extremely satisfied / 7 = extremely disappointed, I’d have to award a score of 4.
By the way, on the other side of town where I live there’s a field covered with solar panels. Yesterday I rode my bike past it and the weeds growing underneath the panels are now starting to come through the gaps between the panels. So it’s possible that in about a week I’ll have another one of those infamous weed-covered PV system photos, like the one I wrote about here. I’ll be going back in a few days with a camera to see if I can get some shots before the owner mows the weeds down.
Photo: by P Gosselin