Have I got the correct size inverter?

[avboon]

I have 12 Suntech STP245S panel [ not my first choice but all we could get hold of in Nov!]and a fronius IG inverter 20. I queried the inverter sizing when this was installed but was assured that it was of sufficient size. I understand maximum output is 2 KW. Today is the first really sunny day we have had now that the sun higher in the sky and I notice we are generating 2.1 KW. I am now concerned that I will be losing generation capacity because of the inverter. I know Inverter should be 80 % of maximum output just worked out mine and it is only 65%
I am only a customer and therefore dependent on experts opinions and there may be something I am missing here. I would be grateful for others views before I consider going back to my installer
Thanks

 

[dansk]

Hi - Yes its too small, you would be better off with a IG30 plus.

 

[wstevew]

It doesn't help that with 0 to +5% output you could be as high as 3087kWp

 

[FB.]

If it was my system, I would be more comfortable if the inverter was the IG 30 - or even a little larger than that if the panels benefit from an ideal South-facing and 35(ish) degree roof pitch.

If there are some special considerations for your array (such as shading in peak summer) then it might possibly (I said might - possibly!) be the case that a larger inverter isn't needed.

 

[avboon]

Thanks for your replies
The roof faces due south, not sure of angle. There may be some shading issues later in the day. 8 panels are on old roof and 4 are on new 2 storey extension, roofs face exactly same direction but old roof is slightly higher and there is a chimney. Panels were positioned to try to reduce any shading. Does this make a difference?
Do you think the small sized inverter is enough of an issue to justify a complaint to my installer?

 

[dansk]

i run it through PV SOL for you and that came back with 2 x IG20 to make this work - so yes your not being unreasonable to go back to the installer. Also if you have shade issues it may be better on an inverter with Duel MPP to mitigate the shade -

The best option for you from what you have said is a Power One 3.0 with a string of 4 and 8 - i checked it works ok.

 

[avboon]

Thanks dansk. I have spoken to my supplier He has agreed very readily to swap for Fronius 30. Apparently that is what he intended should be fitted but Electricians installed wrong one. So glad now that I followed this up.

 

[Cider]

Thanks dansk. I have spoken to my supplier He has agreed very readily to swap for Fronius 30. Apparently that is what he intended should be fitted but Electricians installed wrong one. So glad now that I followed this up.

I would take that with a pinch of salt!