3.76 kwp OK with an SMA 3000HF inverter?

sholtby · Aug 3, 2011

Hi,

Just had a quote for a solar install using 16x Sanyo HIT 235 panels and an SMA 3000HF inverter. The price is £12500.

My initial concern was that the inverter is too small for the panels however the SMA software shows good yields that are very similar to larger inverters such as the 4000TL. I found an Australian forum where the often have panel sizes way larger than the size of the inverter and still get good results.
Can anyone confirm that this system is ok?

What realistic yield can I expect from this system? The SAP figure provided is 3227 or £1397 per year. Panels face south are unshaded and I am in the north east of England. The performance of most systems seem to be higher than the SAP figure is this correct?

Ideally I would like to fit the inverter in the loft as I dont have much space in the garage. Will this reduce performance and reliability significantly as the loft can get quite hot in summer?

Many thanks
Simon

sholtby · Aug 3, 2011

Got these figures for different inverters from the installer. Looks like the smallest inverter is best.

SB3000 HF - 3238Kwh
SB3300 - 3235Kwh
SB3224 - 3224Kwh
SB4000 TL - 3235Kwh

northernsun · Aug 3, 2011

Way back when, when i first did the solar pv training it was fairly common practice to undersize the inverter for better annual yields, especially in the UK. Its easy now to use the software and see which is the best for your system. It may sacrifice a bit from the maximum output but the system will perform better overall, afterall theres a lot less perfect weather than perfect.
This can vary with different modules but is often true, thats the good thing about picking the right one and having a good look at the figures and using software, if you fancy it you can download sunny design for free and check it yourself.

SolarCity · Aug 3, 2011

Your system will probably outperform the SAP figures because of the Sanyo panels and the high efficiency of the 3000HF inverter - although not by a huge amount as the amount of sunlight you get in the north east of England is not quite as high as the SAP figure.

sholtby · Aug 3, 2011

Thanks very much for the replies.
I am trying to work out if it is worth fitting solar panels. There are so many things to consider. The negatives being..
1. Can we rely on the 25 year guarantee and at the rates quoted. The power companies via the 6% levy on energy bills pay but the government controls the framework. Can we really trust this and future governments to keep a promise for 25 years on a crazy price per KWH produced.
2. Reliability of equipment
3. The money to purchase the system is gone and any future interest on it. Interest rates could be much higher in the future.

SolarCity · Aug 3, 2011

I can't really see why the government will ever cut it. By doing so they will save no treasury money and the green industry will take a bit hit. I don't really see the "Cut the FITs" argument at all.

northernsun · Aug 3, 2011

BiggsSolar said:
I can't really see why the government will ever cut it. By doing so they will save no treasury money and the green industry will take a bit hit. I don't really see the "Cut the FITs" argument at all.

I would agree with you that it doesnt make sense, but since when has that mattered with government decisions? That said I think it is incredibly unlikely to cut the feed in tariff to existing renewables owners, I think once your on the scheme you will be fine. I do worry that the scheme itself may take a hit in a few years despite its success- lowering prices and a growing industry.