Friday, December 23, 2011

Solstice thoughts

22 Dec 2011: This year the Solstice falls on the 22nd Dec, and we've been rewarded with a lovely SUNNY warm day. The solar panels are doing well, both PV and thermal.
   The shadows are the longest they will be all year, and from now, the days will gradually get longer and the shadows shorter. The weather may get colder in Jan and Feb, but the PV figures will improve, as long as it doesn't snow. The difference in day length at this time of year is but a few seconds, because the solar altitude follows a SIN curve, and the Solstice is the flattest part of the curve. In 2010, the Solstice day was a grumbly cloudy affair, but in 2009 and this year, we are given a special dose of Sunshine!
   2011 has been a better year for sunshine. December 2011 has already gained more PV power than all of December 2010. Our computed 'annual' figure consistently exceeds 3,300 kWh.
Oct 2010  173 kWh    Oct 2011 207 kWh

Nov 2010 96.6 kWh    Nov 2011  79 kWh
Dec 2010 49.5 kWh    Dec 2011 ? kWh
December 2011 has made 52.7 kWh so far and there are nine days to go, and some of the long range forecast includes sunny days.

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