Suspicious PV data

14 comments started 2023-04-03 last 2023-04-03
GivEnergy Products
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#1 Cloud9

Can anybody advise on what the PV data highlighted below in the photo might mean? It looks a bit suspicious to me?
Many thanks

#2 Cdent

Cloud9 that's the number of watts each string is producing

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#3 Cloud9

Cdent
Think you very much for that. I do realize that, it's more the fact that string one is reading considerably less than string number two. This was in full sunshine with no shading. I am thinking that string one has a problem? Thanks again

#4 Cdent

Cloud9 without knowing your set up we can't really comment. Mine is east/west split so one string is always lower than the other, except around midday. Is it the same other days?

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#5 Cloud9

Cdent
I have two strings, both south facing with no shade until late afternoon so both strings should be producing very similar readings. This just happens in the morning's on sunny days as it ramps up to about 1 kW. Throughout the rest of the day and when it isn't bright sunshine, both strings produce similar readings.
So, if we presume that there is a problem with the string, only when it is sunny and steadily increasing in Pv production in the morning, what on earth could be the fault? Bit of a tricky one๐Ÿค”

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#7 IanMac

Do you have either microinverters or DC optimizers for each panel?

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#8 Cloud9

IanMac
No I don't have those. Shouldn't really need to if all is working well.

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#9 Cloud9

Cdent
Thank you for that. There are similarities but mine isn't when the batteries are full. Mine seems to be first thing in the morning when PV levels are ramping up way before battery levels are high. Interesting to see other problems.๐Ÿ‘

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#10 cluelesscris

Note the drop in current on string 1. Check your connections and (if you know how and can do it safely) the output of each panel. Something is pulling the string down.

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#11 Cloud9

cluelesscris
But only pulling the string down as the sun is coming up higher fairly early in the day and PV levels are rising fairly quickly. When it's not sunny and PV levels are relatively low and fluctuating everything works just fine. System hasn't been installed long so still under warranty so difficult to persuade installers there's a problem! I'm trying to get as much info as possible please so I can tackle them again. Thanks

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#12 cluelesscris

Cloud9 Could be temperature related? Misbehainvg bypass diode? Keep detailed records of the lack of performance and show it to the installers. Something ain't right...

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#13 SilverArt

Out of interest, how many panels on each string?

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#14 dragon2905

I am going to assume you have the panels wired in Series as that's standard in the UK and all PV panels are the same.

In that case you would add the Voltages of the panels together and the Current (AMPS) would be the same as the rating on the rear.


pics for u

Using the above image as an example - 10 panels in total, 5 per string - you would see each strings producing 5 x 41.2V = 206V and Current would be 11.7A (all of these are maximum values).

For Watts (Power) = 206 (volts) x 11.7 (amps) = 2410 Watts (2.41kw)

If you have a bad panel then the entire string will be affected by the lowest common number. Example if 1 panel was only producing 5 Amps then the calculation would look like;

206 x 5 = 1030 Watts (1.03kw)

So the ENTIRE string is affected by a reduction in output.

If the problem is intermittent then that would suggest a connection issue rather than a panel issue as a panel issue would be constant and a connection issue may get better (or worse) with temperature or water.

Hope that helps