Renewables: "talking 'bout my generation"

EricMears

EricMears wrote: »

Another quite good day 20.2 kWh which included one peak very close to 4kW (a sunny spell immediately following a heavy shower) and several others above 3.5kW but several deep dips too (e,g. 180w at 14:20).

Getting very close to July pvgis forecast. 30.7 kWh needed in two days which is rather less than any two of last 4 days. Forecast isn't good - but then neither was today's.

Seaweed has let the Met Office down again !

Today's forecast was pretty bad but the actual generation was 17.22 kWh (but still generating 40w so it may creep up a little) which is better than pvgis expects for an average July day.

Now only need 13 kWh tomorrow to match the pvgis prediction. Again, weather forecast is awful but am consoling myself that they've been wrong before.

EricMears

Martyn1981 wrote: »

Local overvoltage problem, causing intermittent system shutdowns on the SB4000TL's, but surely would affect both houses the same if next door.

Not necessarily. Two adjacent houses may well be on different phases and if there's a nearby unbalaced 3-phase load you could have voltage problems on one phase but not the other. Have to say that's a pretty unlikely scenario though.

shafeeq

Hi

11.35kwh. 1 day to go for a first full month for my system. 17kwh shy of pvgis prediction for July..

Shafeeq

Oscargrouch

Ferdy147 wrote: »

Anybody got any ideas on this one? Is something wrong or is it within normal variance?

Is there something that needs to be looked at or is that kind of difference to be expected?

Martyn1981 wrote: »

Best of luck, and you will let us know what you find won't you (and by us I of course mean 'nosey Mart').

Mart.

I think we will all be interested to hear how this one pans out.

My thoughts would be as Mart suggested; 'speak with the installer'. Two identical systems, side by side, everything being equal, even the weather; should not be as much as a 10% change. Certainly sounds like some type of tech. failure; intallation problem without doubt...:(

11.9 kWh today, graph looked like a sky-scraper sky line..:rotfl:

legoman62

17.72kWh today. Just passed June's total.
Rainy day tomorrow:(

zeupater

Ferdy147 wrote: »

Thanks for both your replies guys. Yes both were installed by the same company and when we took delivery of the kit it was all from the same place and same delivery so I'd assume there's no difference in the components.

Will check the string voltage when I'm back home at the weekend and see if there's anything noticeable there. As you say the performance reversal is odd as it was originally the parents house that was causing the concern (Feb wasn't a great month but on the one day of sunshine my sister's did 17.xkw and my parents 14.xkw).

Overall I'm quite happy with the figure's, had there not have been one next door to compare with I wouldn't have thought anything was wrong. As of this morning my parents meter reading was 2050 and my sisters I imagine was probably about 1900. Both systems were complete on the same day - 9th Feb - so not yet 6 months and the weather hasn't been great so I'm quite happy with the numbers so far.

Hi

With a 3.92kWp system you'll likely have two strings, one on each MPPT ... If the 3.92 is 16x245W panels with a split of 8+8 the simple test is to install SunnyExplorer and check that the the power output on each MPPT is the same, or very similar ..... This is how I check our panel performance on a SB4000TL although our strings are configured differently ...

Repeat the above a couple of times as the sun moves around just to check that there isn't any shade from something like an aerial or overhead cable causing the problem at a particular time and sun angle above the horizon, which could explain why the difference varies by month.

Another simple possibily is the relative preference of the two properties for the local doves & pigeons - do they tend to sit on one property & not the other ? ... if so get some binoculars out and check for large splats as these can seriously effect the performance for a while ....

HTH
Z

Oscargrouch

Ferdy147 wrote: »

Anybody got any ideas on this one? Is something wrong or is it within normal variance?

Since then my sisters house is producing noticably less than my parents - say 10% less when you look at the inverter or generation meter readings.

Is there something that needs to be looked at or is that kind of difference to be expected?

Ferdy147 wrote: »

Overall I'm quite happy with the figure's, had there not have been one next door to compare with I wouldn't have thought anything was wrong. As of this morning my parents meter reading was 2050 and my sisters I imagine was probably about 1900. Both systems were complete on the same day - 9th Feb - so not yet 6 months and the weather hasn't been great so I'm quite happy with the numbers so far.

Your two figures of 2050 & 1900 indicate that the difference is 7.31%, so closer to 7% than 10%.

Comparing figures from my inverter to generation reading, inverter shows 1770kWh – GM 1723.6 = 2.62% difference to date. When the system was first installed, the initial difference was >10%. As time goes on the percentage is getting lower as the numbers get higher. Perhaps it is worth logging each day what each system is doing from the GM readings; you may find that some days one property does better than the other and vice a versa, but overall one scores better over a longer period of time (if that makes sense). Even though both systems are identical, in theory, there are also, variables. Cable run lengths, Inverter settings, Panel manufacturing etc. etc. etc. Worth doing a comparison of both to PVGIS figures, you may find that you have been lucky enough to have one system over performing. In reality, I guess you need to have the above checked out and ‘suck it and see’ for 12 months and then compare the annual performance of the two in percentages to see a fuller picture. Get a suitable Excel sheet setup and put in the data daily, to see what picture emerges. By then you can wear your 'Anorak' with pride....:rotfl:

EricMears

EricMears wrote: »

Seaweed has let the Met Office down again !

Today's forecast was pretty bad but the actual generation was 17.22 kWh (but still generating 40w so it may creep up a little) which is better than pvgis expects for an average July day.

Now only need 13 kWh tomorrow to match the pvgis prediction. Again, weather forecast is awful but am consoling myself that they've been wrong before.

Another day of indifferent forecasting ! Supposed to be no sunshine, light rain am & heavy rain pm. In fact we had some heavyish rain very early am and no rain at all in afternoon - indeed we even had a few spells of watery sunshine. Sometimes I wonder why I bother looking at weather forecasts (then I remember it's to laugh at them).

Generated 7.41 kWh today - not the 13 I would have needed to match pvgis.

That means 449.92 kWh for the month so 6.08 kWh below pvgis figure of 456 kWh - a 'shortfall' of 1.3%

July was better than June but still not as good as May.

For 11 complete months, I'm actually 12.7% up on pvgis

If the sun doesn't shine at all in the next fortnight, my SP investment will have returned 12.8%. Hopefully, it will and I'll do even better.

shafeeq

Hi

3.20kwh today.

Shafeeq

Fruit_and_Nut_Case

I managed 491KWh in July, 100.8% of PVGIS estimate after a shaky start. I think it would be churlish to complain.