Problem with array. Heat shading?

[Stephen]

We are having an issue with an installation that we have carried out and we believe the issue may be with the modules.

Installed on a fantastic aspect we have 16 number Sharp NU245 modules and a Diehl 4300S inverter. We did have a 3800S but changed it when the supplier suggested that the inverter was just that little bit too small. The DC run is around 5 metres and the DC run is almost 20 metres.

Does anybody have any suggestions? We have found information about heat shading could this be the issue?

Thank you in advance for your help.

 

[SolarCity]

What is the issue that you've been having?

 

[Stephen]

At times when the sun is at its brightest the inverter cuts out completely. The solid green light on the inverter starts to flash.

The yields from the system has not been anywhere near what we or the customer would have expected, especially when looking at similar and even smaller installations.

 

[SolarCity]

Could the less in yield be down to the fact the inverter keeps cutting out? Have you checked the instructions to see what the green light flashing means? Are there any messages on the inverter?

 

[Stephen]

There are no error messages which is making things very difficult and on an overcast or not so clear day the system is generating without interuption.

When the green light is flashing the inverter is not generating (zero watts being generated) at all and is in standby mode.

 

[dansk]

Hi,

I just run it through PV SOL and it doesnt come back with any problems, my only quarm is the 4300 is rated over 16Amps - and technicaly this is over the G83 16a limit unless all has been taken care off - sorry dont mean to add to the problems, but i would ask the installer to come back, it should have been wired as 16 panels on one string and i cant see a reason why it would cut out.

 

[Stephen]

I beleive the inverter is fine and as time goes on I am thinking there is an issue with the modules? Would you agree? If so do you have any ideas what the issue could be? We are thinking maybe a poor connection or faulty panel but I know you seldom come across a faulty module.

 

[dansk]

If it was a connection it would do it all the time is my guess - without an error code its hard to say - also the 3800 would have been ok, not sure why they changed TBH.

Sorry cant help further -

 

[pjcomp]

You say it's good on an overcast day, but cuts out when the sun's bright. Where is the inverter sited? Max operating temp for a 4600 is 60 degrees - admittedly that's very hot, but if it's living somewhere it gets well-cooked ....

PJ

 

[Stephen]

The inverter was replaced because the supplier said although it was optimally sized there was one warning on the Diehl sizing tool and because it is set up in one string of 16 modules only another Diehl would have been seen as a sensible option.

 

[Stephen]

The inverter is in the loft on the gable wall but it does not get anywhere as hot as that.

 

[pjcomp]

Diehl have a very helpful tech support department - email them at [email protected]

PJ

 

[SolarCity]

It may be high grid voltage. Have you done a check on the voltage?

 

[Stephen]

Again this is fine and the local DNO have checked the local supply and have said there are no issues.

 

[BruceB]

I do not know the Diehl inverters, but it sounds like an overvoltage problem.
Do not rely on the DNO's opinion, they have little interest in finding a problem their side. Measure the voltage at the inverter terminals when operating.
Have you designed for <1% voltage drop on the ac side?
You could also measure short circuit current when the panels are in bright sunshine to confirm it is not a connection problem on the dc side.
Regards
Bruce