Wednesday, January 5, 2011

PV Harvest for 2010

5 Jan '10: As this is a time for reviewing the previous year, here is a diagram of the PV harvest for the year. Although the specific roof is facing east, the general trend of 'sunniness' is indicated, including some clear groupings of low or high readings when we had extended cloudy times, or sunny spells.
 Our total harvest from 1 Oct'09 to 1 Oct'10 was 3,325 kWh which is a lot more than we were led to expect from the PVGIS site, from which we expected about 2,850-2,900 at best.
  At this time of writing, in Dec and Jan, we are living through a time when we think that that 2.5-3.5 kWh is an extremely good capture.
  In the best times of mid summer, we are regularly over 20 kWh.
  If we lived in the south of England, or had a roof that was more south facing, it would be even better.


  1. How many kWh did you get in 2010? If you put your system in this:

    How much is difference.


  2. It is comparable, indeed, we had a good summer so it was better. we had 3325, and should have got about 2850. our winter is terrible as we have a large hill to the south, so sunrise and sunset are an hour different making our daytime sunshine 2 hours shorter. the summer is good, no overshading problem there. If you use PVGIS with our data and assume NO system losses, you get about the accurate figure. This is because some basic system losses are included in the calc, and the losses you put in that dialog box is for additional losses such as shading.


Comments will be moderated before showing. Please make them relevant to the subject of the posting. Comments which advertise commercial products will usually be deleted.

Popular Posts