I was wondering if anyone could help me understand what happened with my system after a mistake has been made. The installer was supposed to put 5.6kW solar panel system with a 5.12kW inverter and a 5kW battery which they did but by mistake they installed a 8kW inverter instead. This fact came to light only two months after installation. I am not planning to add more panels. Am I disadvantaged by this mistake and should I demand a replacement of the inverter for 5kW? I’ve read that, although oversized inverter may have a longer life span due to less stress, it might actually produce less electricity compared to the matching or undersized inverter as it ramps up slower at periods of low solar activity (mornings, evenings, winter, autumn).
Oversized inverter
- Thread starter archer327
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I would be more concerned about battery charge rates, and how that has been set up.
Undesizing inverters is old hat idea based on old style inverters that were far less efficient than today's offerings.
If you can post the spec sheets that would be useful.
Thank you binky. The inverter is 8.8kW Sunsynk hybrid inverter connected to 5.32kW Sunsynk battery. The battery is set up to discharge up to 20% max so it never goes below 20%. I suppose you can go below that at the expense of life span of the battery (Sunsynk says the battery will withstand 6000 cycles at discharge level 20%). It all works well so far but I don’t know how it would compare with the 5.12 inverter in place as originally planned.
I doubt you will see much difference from the smaller inverter except at dawn and dusk, when any potential outputs would be low.
With regards to the battery, depth of discharge is not what I was thinking of. Charge rates ie will charge/ discharge at say 3kw, 4 kw etc. The larger the inverter the higher charge rates tend to be, which may or may not match the battery. But as its all sunsynk gear I doubt there's any issues with that either. In fact higher discharge rates could well work to your advantage.
With regards to the battery, depth of discharge is not what I was thinking of. Charge rates ie will charge/ discharge at say 3kw, 4 kw etc. The larger the inverter the higher charge rates tend to be, which may or may not match the battery. But as its all sunsynk gear I doubt there's any issues with that either. In fact higher discharge rates could well work to your advantage.
johnb2713
Well-known member
Unlikely if the inverter is on their approved list and the export limit is set accordingly.
If it was a mistake the paperwork could be listing the original inverter and I'm not sure limits would be sat if they didn't know it was the wrong one
johnb2713
Well-known member
Easy adjustment to make, dial it in and then its a win win situation.
Depends on the original application, but if export needed to be limited and installers set that correctly it's a bit of a non-issue.
Just catching up.
I would also keep the inverter.
From memory, sorry cannot check right now, but the sunsynk battery charge discharge is of 2.5kW. This is quite low but yeah it is only a battery. In the future if you add more batteries, or more panels, or charge from the grid the many more batteries you’ll have, you ll find that your 8kW inverter was the right one.
I would rather be in that situation than the other way round (ie they put a smaller inverter)
I would also keep the inverter.
From memory, sorry cannot check right now, but the sunsynk battery charge discharge is of 2.5kW. This is quite low but yeah it is only a battery. In the future if you add more batteries, or more panels, or charge from the grid the many more batteries you’ll have, you ll find that your 8kW inverter was the right one.
I would rather be in that situation than the other way round (ie they put a smaller inverter)
They re-applied now for the larger inverter which is already installed. That’s another problem - they won’t give me the MCS certificate until this second DNO is granted and I can’t join SEG tariff without it.
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