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I have 9kw of Aiko panels in mind for the roof
What size inverter will I need?, 6-8kw?
If the DNO wont let me export the full 7.6 watts I think I can apply for on G99, do I change down the inverter to a smaller one or limit the export to the guaranteed 3.6 then apply again later?
What brands would people recommend/avoid for Inverters?
What mid priced brands would people recommend/avoid for batteries?

Snuggy wrote: ↑Fri Jun 21, 2024 8:45 am I have 9kw of Aiko panels in mind for the roof
What size inverter will I need?, 6-8kw?
If the DNO wont let me export the full 7.6 watts I think I can apply for on G99, do I change down the inverter to a smaller one or limit the export to the guaranteed 3.6 then apply again later?
What brands would people recommend/avoid for Inverters?
What mid priced brands would people recommend/avoid for batteries?

I suspect there will be many possible answers to this!
In general it is pretty common to have more capacity of panels than the inverter size, as most of the time the panels will not operate at full power, especially if the panels are not south facing.
eg. I have a Sunsynk 3.6kW inverter, and it is rated to go with panels up to 7.2kW.

If I was doing it again, I would probably go for a bigger inverter, mainly because with a 3.6kW inverter you are always limited to 3.6kW power flow into the house / into the batteries / from batteries.
I have 2x 5kWh batteries, which could handle 5kW in/out with a bigger inverter, but I am limited to 3.6kW currently.
I started out with only 1x 5kWh battery - which would only provide 2.5kW to the house, which meant that every time I switched on the kettle, it would draw from the grid, no matter how full the battery was - so I added a 2nd battery 6 months in.
In general, plan for the future - what will you realistically want going forward and plan for that - either buy it all up front (ouch), or make sure you have an easy upgrade path. Buying up front has the advantage of getting VAT free prices as long as a registered installer is fitting it.

Thank you. I think sunsynk inverter may be the way to go as givenergy only do 5kw on a single phase. have you been pleased with it?

Yes I think I will put as much money intp getting stuff on the roof and the inverter, and maybe have to "waste" power, then start building on batteries when I see what is cost effective

As part of my setup I have one 4kW inverter with 9kW of NE facing panels on it for the winter. In the summer I actually turn it down to 1kW or it would run at 4kW all day and I have enough production without it.

Snuggy wrote: ↑Fri Jun 21, 2024 8:45 am I have 9kw of Aiko panels in mind for the roof
What size inverter will I need?, 6-8kw?
If the DNO wont let me export the full 7.6 watts I think I can apply for on G99, do I change down the inverter to a smaller one or limit the export to the guaranteed 3.6 then apply again later?
What brands would people recommend/avoid for Inverters?
What mid priced brands would people recommend/avoid for batteries?

I don’t recognise where the 7.6 (kilo) watts comes from. Are you on a two phase supply? - very rare for domestic.

You need the hybrid inverter to be able to be able to handle up to 80-100% of the rated panel output as this will supply battery charging load, domestic load and export load. 14 years ago when FITs started, there was a school of thought that oversized inverters on the basis that the electronics would be working less hard and last longer. Since then reliability has improved.
When hybrid inverter output less battery charging load less domestic load might be greater than 3.68kW or any DNO limit, the clever electronic wizardry will limit the export to 3.68kW/DNO limit. Thus there is no merit in just getting a smaller inverter.

You can juggle the rate at which the inverter charges the batteries so that the batteries don’t get full too quickly and then have export limited.

Happy with my sunsynk ecco3.6kw invertor.
Wasnt at first as it kept erroring out and tripping, but found that to be an installers error (too much pv on a single string).
Have to say Sunsynk tech support were very patient with my insisting the product was duff rather than an installer error, which was proven in the end.

Invertor handles upto 7kw of PV (mine has 5.45) and can charge batteries/discharge to the house at 3.6 from the grid BUT charges batteries at a higher rate (dont ask me how?) when using the PV itself. Seen mine regularly pushing 4.8kw into my Pylontechs on a sunny day. There is a video of Sunsynks Keith Gough explaining it on the net, but he's like the energiser bunny on acid and is too difficult for me to follow with his scattergun demonstrations, but trust me it does do this.

Manual is utter rubbish mind, but lots of features and easy to use once you understand what tick box does what.

Make sure you get all the panels you can fit on the roof in one go, im finding extending with identical panels even just 6 months later is not easy.

John_S wrote: ↑Fri Jun 21, 2024 11:38 pm
I don’t recognise where the 7.6 (kilo) watts comes from. Are you on a two phase supply? - very rare for domestic.

Yes we are single phase

I asked PV installer
Did you confirm whether the G99 forms can go up to 8kw and can we?
Installer replied
The G99 application can go up to 7.68kW.

resybaby wrote: ↑Sat Jun 22, 2024 8:04 am Sunsynk tech support were very patient with my insisting the product was duff rather than an installer error, which was proven in the end.


Make sure you get all the panels you can fit on the roof in one go, im finding extending with identical panels even just 6 months later is not easy.

Looks like that is a vote for Sunsynk then.
Yes deffo cramming everything on the roof I can. Most people are laughing as me so you have given me a bit if confidence, at least in that area!

Snuggy wrote: ↑Sat Jun 22, 2024 9:24 am

resybaby wrote: ↑Sat Jun 22, 2024 8:04 am Sunsynk tech support were very patient with my insisting the product was duff rather than an installer error, which was proven in the end.


Make sure you get all the panels you can fit on the roof in one go, im finding extending with identical panels even just 6 months later is not easy.

Looks like that is a vote for Sunsynk then.
Yes deffo cramming everything on the roof I can. Most people are laughing as me so you have given me a bit if confidence, at least in that area!

Most people are narrow minded superstitious idiots who don't look beyond the last thing they were told to think. Well done for not being one of them! If you have a hot water tank at your home it can be the simplest and cheapest way to get into stored energy via a diverter. Are you thinking of batteries or just PV at the moment?

I am 6 years in with a Goodwe Hybrid inverter to control power flows & battery charging. No problems other than a wee bit of comms due to server issues in Goodwe Germany. For batteries, a fair few members use Pylonthechs as a reasonable plug & play solution. There are other commercial battery solutions which are popular too as well as the DIY route. A reasonably common solution is to fit X amount of battery at a commercial product level then add to later as DIY for more capacity as your experience level grows and you realise just how much PV can do to knock down grid reliance and FF consumption.

Well we were thinking of batteries but our neighbour informs us the dormer has never been done in our 1960's house. I doubt she's right but she has lived next door for 65 years. It looks good but we think it sensible to get a flat roofer to redo before we get the solar panels wrapped around it, so I guess that is the battery gone budget wise, or at least reduced in size!
I understood diverters were about £4-500. Our tank is old and the whole hotwater system needs ripping out and redoing. Probably best to look into a hot water/heating system I can control from my phone when the suns out, must be something about these days but will have to investigate later.