Expected PV power in winter sun?

[Dad]

Installers are coming out tomorrow afternoon so I’ll report back!

Yes when I say I can see the panels in the sun I am referring to the four on the south elevation.

Tomorrow I’ll find out what they have done regarding the string (did they do it as one string etc) and what optimisers I have set up. When we were surveyed they recommended four optimisers and when the roofer installed the panels and birdproofing he said he put eight on. I’m not even sure head office were aware of that (I have pointed it out since).. so that needs reviewing too.

Let’s see!

[Dad]

Update.

So on a positive note the installation company sent an electrical inspector to the house rather than someone from the installation team.

The inspector was not satisfied with the quality of the wiring and a few other regulatory issues which he has reported back on so they get remediated.

From my PV low performance point of view he has discovered (by working on the inverter) that my voltage is low the amps are almost non existent. So something isn’t quite right. He’s asking the installation team to come back and remediate and he said he wants to be present when they do. He said it could be optimisers/wiring etc. they need to also test the panel readings with a radiation meter (may have misunderstood that bit).

I’m actually pleased with the outcome tbh as he seemed an honest guy.

[Dave Foster]

Update.

So on a positive note the installation company sent an electrical inspector to the house rather than someone from the installation team.

The inspector was not satisfied with the quality of the wiring and a few other regulatory issues which he has reported back on so they get remediated.

From my PV low performance point of view he has discovered (by working on the inverter) that my voltage is low the amps are almost non existent. So something isn’t quite right. He’s asking the installation team to come back and remediate and he said he wants to be present when they do. He said it could be optimisers/wiring etc. they need to also test the panel readings with a radiation meter (may have misunderstood that bit).

I’m actually pleased with the outcome tbh as he seemed an honest guy.

Sounds like a good response, either a faulty panel or optimiser holding back the string - to be fair something the installation team would probably have picked this up straight away had it been in the warmer months with higher solar generation.

Your very close it's an irradiance meter

[Dad]

Ha! Good to know they are not checking for nuclear radiation then!

Other thing is that it has been set up as a single string.

[calum]

Given the number of panels a single string does make sense. Hopefully they can resolve it quickly.

[Dad]

So if I log on to Fox Cloud I can see that for today the graph for volts is around 300+.

My PV power is between 0.1 and 0.2Kwh

My PV current is between 0.5 - 1.0 amps.

I assume that’s not normal? What do you guys get for amps?

[Dave Foster]

So if I log on to Fox Cloud I can see that for today the graph for volts is around 300+.

My PV power is between 0.1 and 0.2Kwh

My PV current is between 0.5 - 1.0 amps.

I assume that’s not normal? What do you guys get for amps?

Your volts looks correct, my front array today (8 panels) peaked at 6A, the rear array (5 panels) peaked at 8A

[Dad]

Thanks Dave. So my amps didn’t exceed 1.0 amps today and 0.7 yesterday. The inspector says that points to an issue somewhere with the circuit (wiring, optimisers) or panel issue.

[calum]

8A on the rear string (x8), only 2A on the front (x6) but that doesn't get much sun this time of year, the sun doesn't get high enough.

Now they've identified that there is a problem hopefully getting it resolved is straightforward!

[Dad]

I owe the community an update on this.

The installer came back and reconfigured the panels as two strings of four and this has made a big improvement. In summary it appears to be resolved now and generation is looking much better!

[calum]

Good to hear the installer stood by their work and resolved the problem - there's too many stories on here of installers being unwilling or unable to assist with issues.

Was there any faulty hardware in the end, do you know? Or was it just down to the string configuration?

[Dad]

I believe it was just string configuration. I think the optimisers (one in every panel) in the single string of 8 was just not working for whatever reason.

To put it into perspective… previous daily PV total yield was approx 1Kwh but usually closer to 0.5-0.7Kwh (using Energy Stats data) for the whole day. And the sunnier it was the lower the generation.

Now getting a total PV yield of 1.5Kwh on a really bad day and 4Kwh on a better day with some sun. Can easily see this rising sharply with long and sunny days.

Also the string that is due South is producing approx 2/3 of the power when sunny. When cloudy the two arrays are almost equal.

It all just feel right now depending on the weather conditions.

[RedBaron]

Definitely sounds fishy to me. Even in the middle of winter, my 6.24 kWp array with 5 kWp Inverter produced about 350 kWh over January (11 kWh per day), and kept my overall energy bill down by about 3/4 (on Octopus Agile import, fixed 15p kWh export) of what the electricity bill would have been without any system on a fixed rate (e.g. annual rate of about £500 instead of about £2000).

Even though you seem to be making some progress, here are a number of thinks I can suggest which may help build a case:
i) Use one of the web based solar calculators to calculate expected yield for your array, taking into acoount the orientation etc.
ii) Take photographs of the array at 1 hr intervals during a sunny day to look at the issue of shadowing. However, with panel optimisers you are much less prone to shadowing problems - the photos would enable an estimate of how much to discount due to shadowing.
iii) Use the energy stats app to aggregate your data and actually measure the total output over a period - the foxess data isn't perfect but it is sufficiently good for this.
iv) Having started writing this, I can't remember what you said about a battery. At this time of year, smart use of a battery on Octopus Agile gives as much benefit as the panels themselves, so whilst the panels are getting fixed you could focus on optimising use of the battery if you have one installed.
v) In principle, one experiment you could do is during constant light conditions (and no shadowing) cover each panel in turn and look at the reduction in total output on PV2 - it should be the same for each panel. Depending on your installation, this test may not be practical (I live in a bungalow ).

Regards,
Geoff

[SolarJunkie]

Definitely sounds fishy to me. Even in the middle of winter, my 6.24 kWp array with 5 kWp Inverter produced about 350 kWh over January (11 kWh per day)

Is that yield, or solar generation, as I wouldn't have thought that we would have had enough sunlight for that amount of solar generation, in the UK?

[Dad]

Definitely sounds fishy to me. Even in the middle of winter, my 6.24 kWp array with 5 kWp Inverter produced about 350 kWh over January (11 kWh per day), and kept my overall energy bill down by about 3/4 (on Octopus Agile import, fixed 15p kWh export) of what the electricity bill would have been without any system on a fixed rate (e.g. annual rate of about £500 instead of about £2000).

Even though you seem to be making some progress, here are a number of thinks I can suggest which may help build a case:
i) Use one of the web based solar calculators to calculate expected yield for your array, taking into acoount the orientation etc.
ii) Take photographs of the array at 1 hr intervals during a sunny day to look at the issue of shadowing. However, with panel optimisers you are much less prone to shadowing problems - the photos would enable an estimate of how much to discount due to shadowing.
iii) Use the energy stats app to aggregate your data and actually measure the total output over a period - the foxess data isn't perfect but it is sufficiently good for this.
iv) Having started writing this, I can't remember what you said about a battery. At this time of year, smart use of a battery on Octopus Agile gives as much benefit as the panels themselves, so whilst the panels are getting fixed you could focus on optimising use of the battery if you have one installed.
v) In principle, one experiment you could do is during constant light conditions (and no shadowing) cover each panel in turn and look at the reduction in total output on PV2 - it should be the same for each panel. Depending on your installation, this test may not be practical (I live in a bungalow ).

Regards,
Geoff

Apologies Geoff, I hadn’t seen your reply.

Since this was reconfigured to two strings of four panels each it has been working actually better than expected. I’m getting 10Kw+ solar yield most days now and that’s increasing as we head into summer.

Yes I have batteries.. x5 HV25s but planning to go to x7 soon as battery prices have dropped and we are due to have our Aga converted from gas to eControl electric in May so the extra battery capacity will be worthwhile. Using Octopus to top them up overnight at 7.5p.

[snb]

Hello,

I am not sure what to do, I had a new system installed 11kwh and it only produces between 0.1 and 0.3 even on sunny days.
Installer said that maybe 1 out of the 24 pannels have some shadow because of a tree and is bringing the production down to all of them.
Any advices?

Kind regards

[Dave Foster]

Hello,

I am not sure what to do, I had a new system installed 11kwh and it only produces between 0.1 and 0.3 even on sunny days.
Installer said that maybe 1 out of the 24 pannels have some shadow because of a tree and is bringing the production down to all of them.
Any advices?

Kind regards

When you say 0.1 - 0.3 do you mean power generated per hour (kWh) or the total generated for the day.

At this time of year, with the suns elevation so low shadows will be a problem early and later in the day and the generation will be almost at the seasonal lowest.

To check for shadows take pictures of the array every hour on a bright day and work out whether any shadows are because of the suns low elevation or something that might occur all year round - if the latter you might want to consider optimisers on the affected panels.

For comparison this is for a 6kWh system over the past week, part east facing, part west facing

[WyndStryke]

Installer said that maybe 1 out of the 24 pannels have some shadow because of a tree and is bringing the production down to all of them.

You could try adding an optimiser to that one specific panel, and see if there is any difference afterwards.

[TonyHoyle]

Shadow on one panel won't affect the others - that's something that was true in the earliest days of solar panels but hasn't been a thing for a long time (cynically I wonder if installers keep saying it to upsell optimisers where they're not needed).