Monday, June 28, 2010

Page all about Photovoltaic

28 June: On the Rushcliffe Solar Website, I published a page with Frequently Asked Questions about Photovoltaic installations. There is also one on the Financial aspects. There are many such pages on the web, and most of them agree, especially since a few months have gone by since April 2010 and pages have had time to update. But I get asked these questions all the time at meetings with people, so I thought that it was time to answer many of these, succinctly.
   One thing I have been getting my head round is Payback on PV installations. Instead of the Simple calculation (divide cost by income) you can do a Compound calculation, assuming that energy prices will increase over the years, and that the Feed in tariff will be index linked. In that case, it shortens the payback period by 10% or more. £1000 a year income over 25 yrs sounds like £25k, but if energy prices grow by 3% annually, that is £36.5k.

   Sorry that I have been a bit quiet on these pages about Charging the Earth, but it's a long summer with not much heating to do, and lots of solar heat being buried into the boreholes. The GSHP is performing well, using 39 kWh less in June than it should have done by normal expectations.
   I do have projects in mind, particularly, the addition of the Savita panel to the south wall, activating the spare PV panel, and some Heat Recovery ventilation. And Rushcliffe Solar has now taken off, taking much of my time for the summer.
  I have a holiday coming up, ten days in France. I will probably turn the sunboxes off, to reduce the pumping energy consumption (because I believe that the most efficient use of these is when the GSHP is regularly pulling the heat out in the same day). In summer, pump could be 0.8 kWh per day, and although this is mostly powered by the roof, the system continues to run until 10pm or 11pm. Alternatively, I can push the activation temperature from 20 to 30ÂșC ensuring it runs only when the sun shines.
    Interseasonal charging to make the GSHP more efficient in Nov/Dec will not really be affected by whether they will be on or off for ten days in July)

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