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Message started by William of Orange on May 11th, 2008 at 10:48pm

Title: Re: Spending dosh to save it ! MPPT Charge Control
Post by William of Orange on Jul 2nd, 2008 at 5:02pm
As the ambient tempreature increases the output from you solar panels will fall. Although high sun intensity provides more amps high ambient temperature reduces voltage. Taking the intensity of full sun as pretty costant as your panels get hotter they produce less power.
A cool panel in full sun in winter can produce about 30% more power than a hot panel in full sun in Summer. The problem is more acute if your panels had poor cooling ie too closely mounted to  the roof not allowing good ventilation.  

Also you panels are sized as for eg 130 watts (STC) which stands for Standard Test Condition part of which includes a fixed temp factor of 25 degrees C. So to get your rated STC power would require perfect solar alingement 25 degrees C panel temp. Full Sun. You reallife output will be approx 75-80% of your panels STC rating. Although good MPPT controllers can achieve far better than this. On three ocasions this year I have seen over 1300 watts power from my 1200 watt STC array the peak being 1376 watts. Probably only lasted a few seconds but there you go, was in cooler April forwhich my panels are ligned to !

HTH  WoO

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