Panel Performance Issue?

[lennyg]

Lenneg, where do you live, maybe if you are close to one of the experts on here they may pop in and sort things out for you.
Just a thought.

Between Prescot & St Helens Merseyside - Not looking for a freebie, I've paid the installers and they should really sort it. If I can glean information here then knowledge is power.

 

[lennyg]

if you can touch the array from your velux the word "direct contact" springs to mind im assuming the array would have been earthed.

Direct contact? I haven't touched them but could easily touch 2 maybe 3

 

[sedgy34]

Direct contact? I haven't touched them but could easily touch 2 maybe 3

just for peace of mind you might see an earth cable at the ac isolator too

 

[Del Boy]

im guessing you have a string of 10 and a string of 6

This makes more sense... it's almost perfectly a 5:8 ratio... a.k.a. 10:16, you should be getting very near to 1:1.

Not 100% sure what this means in real life terms, but MasterVolt tool says it's ok except the "orientation correction PV power"... I expect the 6 string will just run at a lower efficiency than 2 x 8 strings. Having said that the 10 string will be more efficient, but not enough to make up for it!

Pic of tool attached



Btw lennyg, didn't mean to shock you or potentially upset you with my initial findings, but wanted to show you what the tool was saying!

On a real positive note, the SOLON panels you have are really good!!! And you seem to have a good generation, having 2x8 should make it slightly more efficient, but the best thing is that you can easily spot problems over the long-term. The increase in efficiency is soooo little that you shouldn't be paying to do it but I think the installer should be putting it right for free anyways.

 

[lennyg]

Working all week so haven't been able to update. Yesterday again with full sun across all the panels my readings were c. 1900w on one string and 1100w on the other. The voltages at both were 325v & 140v respectively.

To confirm my spec, the master log software reports it as an xs6500 inverter and the panels are supposed to be Solon 245w of which I have 16.

Do my figures point to anything other than a difference in the amount of panels per string and if that is the only issue then at what point would I expect output greater than 3kw?

 

[Gavin A]

To me that looks from the outputs like they've run it in a string of 10 panels and a string of 6 panels, though the voltages more suggest 11 and 5 - is the bigger portion of the array shaded at all?

Both configurations would be within the range of the inverter, though I doubt it'd be operating very efficiently as it's massively over specced, which could partially explain the lower outputs.

Either way, it's clear that it's not 8 panels on each.

I'm assuming the voltage readings were taken from the inverter when it was operating?

 

[lennyg]

To me that looks from the outputs like they've run it in a string of 10 panels and a string of 6 panels, though the voltages more suggest 11 and 5 - is the bigger portion of the array shaded at all?

Both configurations would be within the range of the inverter, though I doubt it'd be operating very efficiently as it's massively over specced, which could partially explain the lower outputs.

Either way, it's clear that it's not 8 panels on each.

I'm assuming the voltage readings were taken from the inverter when it was operating?

Thanks for your reply - the array is not shaded at all when the readings were taken - the readings were in full sun. How much overspecced is the inverter and how much am I losing because of such?

 

[moggy1968]

How much overspecced is the inverter and how much am I losing because of such?

massively overspecced. I would use a 3.6kWinverter, although opinions vary

 

[lennyg]

For those not necessarily wanting to read the whole thread, my issue is that my 4kw system with 2 strings is producing max 3kw with one string producing about 1900w and the other 1100w all in unshaded direct sunlight, with the voltage ratios being the same (roughly 2:1) The theory is that the strings are split 10/6 however....

An interesting (or maybe not) further piece of information - This morning we had a very bright morning but with diffused high cloud so the panels were receiving a lot of light but not direct sunlight. Taking readings from the inverter, both strings were performing similarly producing about 500W each and similar voltages on both strings - this seems tome to negate previous posts of the array being split 10/6 as I would expect the ratio between the strings to be the same.