Hi all,
I'm still having a nightmare with my E.ON install. They are now saying that for my 2 elevations that total 5.74kWh (14x 410W) solar, I need a 5kWh inverter. Surely I need something bigger than the max output - so I should be getting a 6kWh Inverter??
If someone can tell me if this is right, the electrician is coming to install in the next few hours - but if it's still wrong I'll send him away
It sounds about right.
I'm not sure that there is even a 6kWh on the market. Yes, there may be times when your PV generates a little more than the inverter can handle. However, that is more than compensated by the larger PV array generating more when conditions are less than optimal. Your system will spend relatively small amounts of time at peak output, but will spend many months generating in less-than-perfect conditions.
"Under-sizing" the inverter is very common practice and in general it works to your advantage.
Cpt Darling my opinion only. I have 7.2 south and west on a 5, and I do see clipping when my battery is full. However I don't think I have ever seen 7.2, so probably you will be absolutely fine. I believe that the rule of thumb is a max of 1.5 x inverter yo panel peak. It's only an opinion though, your choice.
There are far more knowledgable people on here than me who will hopefully chip in, but what I've always been told is that for the 2 days a year your PV array will be generating it's max it's not worth the extra cost of the larger inverter.
Also there's the issue of the amount you're allowed to feed back to the grid. Again, I could be wrong and someone can correct me but as I understand it, if your installer has submitted a G95 (designed for home solar) form the max you can have is 3.6 kW. If they've done a G99 (designed for solar farms and I belive is hundreds of pages long) you can have whatever. There really needs to be an intermediate form for larger dommestic installtions or small commercial installations as I've been told not many installers want the admin of doing a G99.
What I'm not clear on and where I may have lost out is if you can have a, for example, 4kW array with a 5kW inverter instead of a 3.6kW inverter and set the larger inverter to only export 3.6kW to the grid but if the house demand is higher it can supply up to 5kW. The difference in price between the 3.6 and 5 kW inverts is not a lot. Wish I had known more and trusted my installer less before I had mine in.
Cheers, Mike...
Thanks everyone, this is very helpful.
Just panicking that E.ON are getting it wrong again... this is the 3rd time they have tried to resolve the installation issues...
I've been waiting since 31st March for my install to be completed.
Cpt Darling There are bigger inverters, I have an 8kw on one of my systems. But it depends on your peak power, if you panels are split on East West roof's as an example chances are you wont see much over 5kw anyway in which case a 5kw is fine. Also the 5kw will support larger array sizes and "clip" or restrict if needed. But unless your 5.74kw of panels face south id say a 5kw is fine.
Are they installing the 5kw givenergy hybrid?
Cpt Darling Oh I see. Do you know how much wattage is going on which roof? Also some solis inverters support 3 pv arrays. One of the mppts can take 2 arrays if I recall the spec sheet correctly.
I have a 6kw solaredge inverter. FYI
Cpt Darling I have 18 panels split over an East & West roof, I’ve got a Gen3 5kwh inverter, this is what the generation looks like this month
Well its taken E.On this long to recify my inverter isssues, only to mess it up again! Instead of installing 4 & 2 kWh inverters, I have 3.6 & 2... Honesty, its been a nightmare.
I have 15x 395W panels on the 3.6kWh, and 5x 395W on the 2kWh inverters... Got told on Friday that they might have installed the wrong size inverters again! The system has been tripping each day (usually on sunny mornings)
Cpt Darling What do you mean by 'tripping'?
As you have panels in 2 directions I’m guessing at least one of those isn’t south. Typically you would put more panels than inverter capacity and for systems such as E/W it’s a larger ratio the all south.
It’s a balance and we have more than 6kW DC attached to a 5kW inverter. We might get a bit of a clip in the summer, but we get more generation than we would from 5kWp of panels.
Don’t forget also to look at the nominal power (NOCT) of panels as that’s what they’ll more likely to generate vs the STC.
If you’d ended up with a two string 5kW inverter it wouldn’t be a worry.
The 3.6 with nearly 6kWp on it might be over the voltage/current limits for the inverter.[](https://)
Cpt Darling The 32A trip switch in the CU, that connects directly to the Solis Inverter
Is that an MCB or an RCBO.
Is the trip due to overload or earth leakage (RCBO)
Labelled PV/Solar was tripping every day.
The issue was, I originally had 1x 8kWh inverter, which was swapped out to 2 inverters - but the electricians diasy chained them together causing the tripping - only took them 2 months to figure it out! I've now got 2x 32A switches
They are RCBOs and have combined overload and earth leakage detection.
It could be an earth fault due to some water or as someone posted a type A device may trip.
https://community.givenergy.cloud/d/3478-type-a-and-type-ac-rccbrcd-experience