Hello everyone, I'm new to the community.
I have a dilemma on which size inverter to choose with my 5100W solar installation to achieve the best overall system efficiency. I live in Warwickshire, the weather is generally ok, but been given mixed advice on the size of the inverter (3.6kW or 5kW).
Any insights welcome.
Thanks, Krzysztof
I'll let the others give you the technical advice.
However I have 4.25kw array that can hit 4.6kw in the correct conditions. But once my battery is full I'm throttled to 3.6kw.
Now with flux paying decent export rate. I get frustrated everytime I see my generation capped. Or if I am pulling from the grid when drawing over 3.6 but less then 5.
I originally wanted a 5 Kw but was advised against it by my installer. I now believe that the truth is they didn't want the hassle of a G99 rather then for the technical inverter start up voltage reasons I was fobbed off with.
My installer said the same , Bill G
You can easily run out but you cant have too much.
Waterski99 thanks for this. Does this mean when your battery is empty and your array gives 4.6kW the excess goes into the battery, even if you consume 3.6kW AC?
I'm going with 9.5kWh battery so maybe I won't have that problem. Thanks
positor1 depends if you care about a return in investment within the likely lifespan of the kit.
Inverter - may as well go for the bigger option
Battery - don't go over the top, e.g. if you usually use 9kWh, go for a battery around that size. Don't buy two of them.
Waterski99 However I have 4.25kw array that can hit 4.6kw in the correct conditions. But once my battery is full I'm throttled to 3.6kw.
Now with flux paying decent export rate. I get frustrated everytime I see my generation capped. Or if I am pulling from the grid when drawing over 3.6 but less then 5.
I wonder if you can limit the battery charging rate during the day, so that rather than exporting nothing until the battery is full, and then trying to export everything else, you export throughout the day. That way, you might be able to keep the AC output within the limit since the battery will be able to accept the excess. (I'm assuming a hybrid inverter here...)
Krzysztof I went through the same circle of thought.
3.6 or 5 basically the same price.
3.6 nominally more efficient at lower powers ( most efficient when inverter running at close to ful capacity)
5 kW allows for better export.
5 kW More likely to cover house loads, reducing import.
( Assuming battery 3.6kW, plus PV)
Big thing for me was reading about G99, G100 fast track, and various posts telling of months waiting for the G99, blocking install. As I wanted to avoid delays, I did a whole analysis of how often I would have more than 3.6kW PV + a full battery.
In the end I went for a few more panels, and the 5kW inverter. : -)
The worries over the G99 were overdone. The process is very dependent on who your DNO is. Mine is UK Power networks. They have a newish online system for applications, SmartConnect, which allows the installer to do it all online. Also recently they explicitly say that although you need to take the G99 route, they will INSTANTLY accept 5kW applications, by return of email effectively.
Most impressed with UK power networks, despite them primarily dealing with Installers rather than the public, direct phone calls to them were like a breath of fresh air compared with dealing with my installer (F4S). They were also happy to hurry on the Export MPAN, mail me straight back the acceptance email when I struggled to get it from the installer.
So in short depending on DNO, G99 is the installers problem, and can be quick. The 5kW and "one more panel" where you can would be my reccomedation.
TX200
That is a more sensible approach but oddly it seems i have capacity anxiety similar to electric car owners. I can export for 3 hours and still use no (deliberate) grid import daily. lowest I get down to recently is 23% and even that causes slight anxiety lol
"a few more panels"
Yep, if you have paid for scaffolding, best to get as many panels as you can on the roof. 😀
TX200 totally agree. I'm going with 12, max that can be fitted.
Hi all, would a choice of the inverter size by influenced anyhow the fact that I'm planning to get an EV in couple of tears time? Not sure if the charger itself would do the job of pulling as much as possible from the solar and the battery, or would a bigger inverter make even more sense in this scenario. Later down the road I'm planning to upgrade the heating system to a heat pump too. Thanks again for all the help.
Krzysztof
I would guess that with an EV &ASHP on the horizon, you will at least double your kWh daily usage.
At that point you will probably want to add a second battery.
If you just add the battery you will have to pay VAT (£800 for a 9.5kW battery)
If you add a second PV system + the battery, you don't pay VAT
Talk the current and future options through with an independant installer.