@allyfish I can’t yet offer such meaningful figures for our system (8.1 kWp.) as although I have now completed a year’s production, it has been ‘bitty’ due to starting late summer 2022 and adding Tesla Powerwall in November. For all that though, this year-to-date figures do show that July and August figures have been rather disappointing. I have also been informed by the Enphase app that there is an ‘issue’ with the metering of my production and my installers are going to take a look at the CT Clamps at some point. Regards, Toodles

@toodles thank you. Profile of your monthly generation matches mine. Last two months were a bit lower. Year to date solar production has been 2.9MWh. The annual performance estimate for the system was 3.55MWh so it's likely to exceed that by some margin come the year end. Wish I could say that my ASHP SCoP performance estimate was similarly pessimistic, alas not!

I’m wondering if maybe we have a panel not working. Glorious sun all day today and it’s hardly been above 5KW production. Similar conditions a month ago produced closer to 6KW for decent parts of the day.

is it possibly lower sun in the sky or something like that? 

@marvinator80 Remember when panels heat up they can lose about 25% of their atchull capacity.  Could it be that? It is relly hot today.

Posted by: @marvinator80

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I’m wondering if maybe we have a panel not working. Glorious sun all day today and it’s hardly been above 5KW production. Similar conditions a month ago produced closer to 6KW for decent parts of the day.

is it possibly lower sun in the sky or something like that? 

Looking at the first graph, I suspect that there was some clouds coming over periodically. I'm not certain if many people realise, but besides reducing solar PV output when shading the actual panels, clouds can also increase panel output when the panels themselves are in direct sunlight, but are also receiving reflected sunlight from nearby clouds.

@derek-m We have started several morning’s solar wake-up times with fog/mist; the outcome is that the solar production may be double that of clear mornings - don’t get too excited though, I am observing 400-600 watts rather than the more usual 200-400 watts at such times! This early morning light is indirect as there are houses and trees causing shadows when the sun is that low in the sky. Currently, our system is producing approx. 4.4 kW whereas a few weeks back at this same time (13:40), the output was nearer 5.0 kW. The lower angle of the sun is the prime difference but it is also warmer than it has been since June. My ‘bestest’ rate was on 4th June when I saw 7.2 kWp. From the 21 PV panels for a minute or two only. Regards, Toodles.

@toodles

You are indeed correct the 'angle of the dangle' will also have an effect along with the temperature of the panels.

@andris thanks, could be partly that. My ASHP is in direct sunlight and recording 33 degrees, so panels are probably feeling the same, even if the air temp here is more like 22.

It’s produced 26kWh today so far and will likely hit over 30 so I’m sure it’s fine for a 5.4KW array. Need to stop obsessing! 😆

@toodles 6.2KW is my record from 14 panel 5.4kW array. I think that was on a rare sunny and not very warm day in July.

@marvinator80 Just 19.5 kW/h so far today, but the sun was a ‘layabed’ until gone 09:30. Regards, Toodles.

Our ASHP in the back garden next to the back wall of the house reports ‘28 degrees C’ just now and I have just spot checked the temperature of the ground mounted panels in tha back garden; the readings vary between 46-5 and 47.6 degrees C on the front face of the panels. That’s a good 20 degrees of temperature above STC; at approx. 0.25% loss per degree, we are talking about at least 5% loss of production. I don’t know the point at which the panel temperature is measured for STC but assume it might well be below the top glass face and thus, probably warmer than the glass. Regards, Toodles.