Fault on PV System

[norfolksparky]

Hi all,

I am new to the forum so be easy! Lol!

I have installed a 2kw pv system on a house near me 8 panels, sma 2000hf inverter etc etc. I have fired the system up but have only got 0.8A and 104 watts. The sun is blazing here today and can't work out why. I will head back tomorrow to investigate and wondered if anyone can give me some advice as a heads up. I am a sparky by trade so fairly clued up on watts, amps, voltage, volt drop etc etc.

Thanks

 

[Gary K]

Did you take the panel's out of their box's? LOL

 

[poheZ]

You need to give alot more info before someone can help you

I would confirm Voc, Isc as a starting point

 

[norfolksparky]

Voltage on the inverter states 272v and current 0.8A. I am yet to try the Isc as I didnt have time, just turned it off until tomorrow. i measeured the Voc of the string and found 272v so figured things were looking good, until I turned it on! Lol!

 

[sedgy34]

did you put it in sunny design

 

[norfolksparky]

No it was designed by supplier, Ubbink! The panels are Voc 37.2v Isc 8.42A. Can you give me some expected test results before I start please. The only thing was an eversolar inverter was specified but it turned up damaged and they dropped of the sma and said it would be fine?

 

[snoopdog]

No it was designed by supplier, Ubbink! The panels are Voc 37.2v Isc 8.42A. Can you give me some expected test results before I start please. The only thing was an eversolar inverter was specified but it turned up damaged and they dropped of the sma and said it would be fine?

What make model no and wattage our the panels

 

[sedgy34]

No it was designed by supplier, Ubbink! The panels are Voc 37.2v Isc 8.42A. Can you give me some expected test results before I start please. The only thing was an eversolar inverter was specified but it turned up damaged and they dropped of the sma and said it would be fine?

ubbink 250wp modules???????????

 

[norfolksparky]

The panels are Ubbink but I can't find any info on them i think they are made by someone and re labelled/brended which doesn't help. Think i will stick to know brands from now on. What sort of readings should I be expecting?

 

[dansk]

Voc = 297v allowing for tempreture i would be expecting to see 280-290 - Isc is 8.42@ STC, so expect to see 2-3amp, maybe more, i dont often see Isc at STC figures, on a dull day you'd be lucky to get anything over 1 amp.

Testing VOC is a different reading to what the inverter is seeing, inverter will display running voltage rather than open ended voltage - relax man.

Added: Ubink are Delsolar panels.

 

[norfolksparky]

so why the 0.8A running and only around 110 watts?

 

[norfolksparky]

so why the 0.8A running and only around 110 watts? The Irradiance was off the scale of the meter, the sun was blazing hot! Ouch red all over! LOL!

 

[dansk]

What time was it? was it shaded by scaffold pipes? trees? theres 2 reasons why - if the VOC is correct then you know the string is wired correct. It only takes 1,2 or 3 scaff pipes to shading 1 or 2 panels at it will drag the system down something silly.

 

[dansk]

Did you set the inverter to G83 also? just double check for that whilst your at it ;-) (but that wont affect the wattage or DC volts)

 

[norfolksparky]

there was a couple of panels shaded yesterday but tried it again today when it was in full sun and it was the same ish, wattage 66 watts. I have set the inverter to G83 already aswell.

 

[sedgy34]

here you go View attachment ubbink project.pdf

 

[dansk]

Hard to say pal without being there- maybe one of the other lads will know - post up some pictures that may help.

 

[Gavin A]

I'll put a tenner on the system being significantly shaded. Hopefully only by the scaffolding as Dan says.

A tiny bit of shading run the wrong way across the bypass diodes / strings of cells on the panels can cause a hell of a drop in output.

 

[dansk]

Ditto -

 

[norfolksparky]

If there was a small amount of shading would it pull it down that much? from would i think should be 1500w to 1700w to around 100 watts? The system only generated 4.4 kw/hr today?

 

[Gavin A]

It's entirely possible.

All depends on how the shading falls across the panels / how the panels are orientated relative to the shading.

Most HF series inverters have a function called optitrac global peak which can help reduce the shading impact, but only if the panels are orientated correctly, so the bypass diodes can function to bypass the shaded cells... you'll need to download sunny explorer and use a bluetooth enabled laptop to switch this function on (installer password is 1111).

 

[Gavin A]

also, if it generated 4.4kWh today, then it obviously was generating more than 104 watts for a fair amount of the day.

 

[moggy1968]

you've got no flow of current by the sounds of it. where did the reading of 0.8 come from. Are you sure all your connections are ok and the polarity is correct (particularly on the generation meter, a common mistake).
Had you actrually fully energised the system?

 

[norfolksparky]

Good point, there are two panels which are on a lower part of the roof and may well have been shaded or partly shaded depending on the time of day. I think i will test the panels, string and all else and if all ok then get the scaff away and see what happens. Thanks for all your help.

 

[SolarCity]

Before you remove the scaffold, work out when the array will be free from shade.

As Gavin says, you obviously produced some power at some point in the day. Depending on the orientation of your roof you should be able to work out when the shading will be clear (not necessarily midday). Check your readings then.