On Friday, 25 May 2012 10:36:25 UTC+1, The Natural Philosopher wrote:
larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...


Now why would you ever believe that I expected that?

If I were to comment on the capacity factor of a wind turbine, would you
say "I'm surprised you believe that calm no wind generation was expected"?

I was making the point that even WITH nocturnal losses, you might
naively expect 40% or so,.


BUT teh real point is the peak to mean ratio of about 9:1 which means
that the inverter is 9 times bigger, more material intensive and
expensive than it needs to be simply because on average solar panels
produce feck all, but have to be sized to deal with the occasional sunny
day.

I was just making the point that your calcs implied capacity as being over 24 hour days, whereas clearly it should be over 12 hour days; and then you can rightly make the point that dawn / dusk can never been good generation periods, so even with bright skies every day of the year you'd never get near the rated output every hour of the day.

I don't think inverter "overhead" in the way that you describe it is too much of a problem - you can make the same argument with most household features. Most of the time my guttering is over-specc'd to deal with the one period of heavy downpour. My roof is just sat there waiting for a cold, windy day when it is functioning to its maximum. My amp can go up to 11 :-) but that doesn't mean I have a DJ-d club session going on all the time.

(My interest in this is that I do have a solar installation, but I aesthetically like it, I like the fact that my house now requires about 1/3 less carbon generated electricity to function, and it cost me nowt!)

Matt