Solar Panel actual output over day/year versus theoretical output

[Chris Green]

Yes, that seems to be about it. The additional problem/downside being that the average through the winter is going to be much less so, unless you have *huge* batteries, you need to size your system to provide your required average power through the middle of winter.

Thus a 250W panel will probably, just about, run a 10 watt pump (or whatever) through the winter if you have battery capacity for several days. Assuming 12 volts that means you need something in the hundreds of amp-hours capacity to keep your 10 watt pump going.

(We have 3 x 100Ah batteries on the boat with 3 x 260 watt panels, as I said, in France, that can handle a domestic fridge plus some lamps while we're away from mains power)

[Martin Brown]

It is certainly a good working ballpark figure. Though it can be worse than that if a part of the array is ever shaded at any time in low sun.

BTW Do you have demand and load graphs available with 1 minute resolution (or better) over the period of the recent grid SNAFU 9/8

16:52-16:57 ? The ofgem report is well hidden online at:

Looks very much to me like the wind farm at Hornsea was the instigator of the problem that National Grid encountered. 737MW dropped off 230ms after the lightning strike shorted out blue phase. Barford dropped off within a second (their timestamps so far are only good to the second).

[harry]

My 4Kw roof array does 4000Kwh/year approx. (W. Midlands.) It has an almost perfect orientation, open aspect and no shading.

Weather has an effect. hrs of sunshine, air temp, etc. They reckon to deteriorate 1%/year. Newer ones do better I'm told as the technology has improved.

[harry]

On a perfect day, my 4Kw array can generate 30Kwh.

On a bad day in Winter 0.3Kwh. It might only be running at 50w peak. I 'spect if there was thick frozen on snow, I'd get nothing at all.

[Cynic]

A 4kW array in East Yorkshire spends days at a time generating sub 1kWh in mid winter and a few days around midsummer generating 27 kWh with progressive variation between these extremes as the seasons change. Not much point expecting any useful work from the output in December/January

[Chris Hogg]

So what's new?