Renewables: "talking 'bout my generation"

nigelpm

Don't understand why PVGIS is useful on a monthly basis at all.

As Eric says over a longer period - perhaps the life of a PV system it might be useful but short term it is meaningless.

jimmyboy420

nigelpm wrote: »

Don't understand why PVGIS is useful on a monthly basis at all.

As Eric says over a longer period - perhaps the life of a PV system it might be useful but short term it is meaningless.

This just shows a misunderstanding of how we're (or, more specifically, I am) using PVGIS.

If you compare to a benchmark (eg PVGIS) for a given period and you're above it, then it's quite apparent you can consider that to have been a good period (performing above benchmark), and if you're below it, a bad period (performing below benchmark).

Obviously, in any given short term period, you are quite likely to deviate from this sort of benchmark by a reasonably significant amount, but those deviations are exactly the information you're interested in, to determine whether a good or bad month has been experienced.

*If* you were to have a long run of good or bad (7 or 8) months, then this would be more significant than a short (1 or 2) run of good or bad months, but each month is still an observable period in its own right that we can compare to the benchmark quite reasonably.

nigelpm

jimmyboy420 wrote: »

but those deviations are exactly the information you're interested in, to determine whether a good or bad month has been experienced.

Understood, thanks.

tunnel

Whoa....30.5kWh(about 4.7 O's)....where did that come from????

legoman62

tunnel wrote: »

Whoa....30.5kWh(about 4.7 O's)....where did that come from????

Me too! Dull AM... but nice sunny afternoon, to finish with 3.92 O's or 15.7kWh today:T

Dodo0808

19.5kWh here today... surprised and happy with that.

Forecast looks dire for the next few days

zeupater

legoman62 wrote: »

Me too! Dull AM... but nice sunny afternoon, to finish with 3.92 O's or 15.7kWh today:T

Hi

I'd actually have expected far more (1000x) from "16 x 250kWp" panels ... ... perhaps they're dirty ? ...

Z

legoman62

zeupater wrote: »

Hi

I'd actually have expected far more (1000x) from "16 x 250kWp" panels ... ... perhaps they're dirty ? ...

Z

Well spotted:T

Mind you, it took ya almost 2 years:rotfl:

old_grouser

Being a simple soul, I treat comparisons with PVGIS benchmarks fairly lightly. However, in the last 28 days, my system has delivered 400 kWh, which is an average of 4.34 Os per day. I think that's a telling figure for March/April!

Oscargrouch

jimmyboy420 wrote: »

Taking a look at my PVOutput stats, I can see that I am 0.34kWh down on PVGIS, per day, on average to the end of yesterday. Not too bad. But I'd prefer to be above it!

Currently for this month I am at 92% of PVGIS for what that is worth...;)

tunnel wrote: »

PVGIS is the sensible comparison. You input your details and it gives you a good idea of how you should be doing. Comparing against someone elses nearby only tells you that you both may be having cr*p weather/conditions, it doesn't give you any idea whatsoever as to what you should be expecting to generate

Tell me, how do they arrive at the PVGIS figures? It must compare with something or some figures. Please, please don't tell me that it is based on the Global Warming ones.....:rotfl::rotfl:

EricMears wrote: »

PVGS is by far the best (maybe even the only) comparison method that is at all meaningfull. But it's very much a long term thing - there's so much short term variation that one day's output has no 'norm' - even comparing this April with a typical April is pretty pointless.

Comparing with a nearby installation may well be more useful in the short term but you'd need to be absolutely certain that it was a valid comparison - if the other set of panels were pointing in different directions or subject to a different degree of local shading the comparison would be no help at all.

Think you are forgetting (ignoring) about the O's.......:(

4.24 of em today.........