OT Milestone.

[whisky-dave]

I would assume such a measure is taken at midday with no clouds, but as sol ar panels heat up their efficincy decreases. We're running a lab on this sort of thing this year, should be interesting .

It can because of efficincy alters with temprature.

Photovoltaic modules are tested at a temperature of 25 degrees C (STC) ? ?? about 77 degrees F., and depending on their installed location, heat can reduce output efficiency by 10-25%. As the temperature of the solar pa nel increases, its output current increases exponentially, while the voltag e output is reduced linearly.

[Brian Gaff]

I think we all need to unmix our metaphors before it gets confusing! Brian

[Chris Hogg]

Are you saying that Harry's numbers can't be right, because they're too high?

OOI, the Slepe Farm solar farm in Dorset has a load factor of 11.3%, comparing the average annual outputs over six years (544 MWh/yr, 2012

- 2017 inc.) with the maximum rated capacity of 551.2 kWp, or 4828.5 MWh/yr.

[The Natural Philosopher]

broadly yes.

Of cpurse if ytou take a 5KW panel and putr a label on it saying 3KW you can get a much higher capacity factor... :-)

That sounds about spot on and an honest figure.

[harry]

olar panels heat up their efficincy decreases.

? about 77 degrees F., and depending on their installed location, h eat can reduce output efficiency by 10-25%. As the temperature of the solar panel increases, its output current increases exponentially, while the vol tage output is reduced linearly.

It has virtually ideal orientation. Plus at quite high elevation and good cooling.

[harry]

Talking bollocks as usual.

I have two same size arrays, they have similar performances. Different makes of panels and inverters.

The output depends on local weather as well as orientation and elevation. My neighbours have similar results.

I expect newer panels will have an even better performance.

[dennis]

It also means he has had about £14k in FITs.

[Chris Hogg]

You have 21 Mitsubishi TD185MF5 panels*, Wp 185 each (total kWp

3.885), 13.4% efficient, rather less than the ones on that link.

A few years ago you were claiming 4,000 kWh/yr. Now you're claiming

5,000 kWh/year. Apart from your panels getting older and being less efficient as a result, what's changed? I know we've just had a very hot and sunny summer, but 25% more sunshine?

[543dsa]

He got a second set installed later.

[harry]

You're right. I made a mistake counting days. Should have been 2720,

[Chris Hogg]

Yes I know, but he did say this was from his first set.

Which gives a load factor of 11.8%, which I'd say pretty typical for solar panels in the southern half of England.