Dillsue

Hopefully thats a typo and its a G99 approval that you already have in place for your 5kw inverter as G98 only covers you up to 3.68kw. Adding AC coupled batteries will be potential extra export on top of what you already have so a G99 application would be needed unfortunately. Its a shame SE dont do smaller/cheaper or scaleable battery options as a DC coupled system seems to have so many advantages.

Can you get a powerwall for self install?? I thought they had to be professionally installed???

British Gas standard variable tariff is price capped at 36p unit and around 50p a day standing charge. Fairly sure those sort of rates will be available from lots of suppliers

Yep. Speak to Octopus and let them know youre plans. If you have the new system MCS installed then I think youll be able to run all your export from both systems through a single meter, but check with Octopus. Dont forget to speak to your DNO first as its all hypothetical until they give the go ahead.

Yes, if youre getting deemed FIT export payments, as all your FIT payments are based only on the generation meter reading. If youve opted for metered FIT export payments(SEG) then youll need to meter your FIT and non FIT export separately.

Q1- you need permission from your DNO to export more than 3.68kw so you should already have permission for your 10kw system. If you want to export more, you need DNO approval of a G99 application. Q2- no problem running 2 or more systems in parallel. We have 2. Q3- its up to you how you configure things and somewhat dependant on what export your DNO will allow, but altering your FIT system is regulated so understand what the rules are before comitting to altering anything

Your DNO approval is for the inverter which will limit export to the grid from either or both PV and DC coupled batteries. If you have AC coupled then the inverter can only limit PV export and your batteries are free to do want they want. SE are quite limited in their DC coupled battery options. I think youve got the recently launched Energybank or the earlier Storedge system using LG batteries. Other than those its AC coupled with an uplift in DNO approved export limit or an export limitation set up

If you go for AC coupled then the battery pack adds to your potential max export and youll need DNO approval for new inverter AND batteries!

Enough said!! I only looked at the first site which is a US site. Youre better sticking to UK focussed sites as rules and terminology differ from other countries. You are correct that its the panels that do the generating and inverters the conversion.

It was the integral PW one that triggered the 2 inverter discussion earlier!

Speak to them first as you may get an indication of likley export limits without making a formal application. SPEN did an informal assessment on our limit and we had an agreement in a few days. Sent the formal G99 application in to reflect what we'd already agreed so straight forward approval. Not sure all DNOs are that slick though!!

Theres a DC-AC inverter in the powerwall on top of the SE PV one!

Is that a UK spec G99 compliant inverter?? AFAIK that feature wont be in a UK spec inverters firmware???

You can do all of those things. Plenty of good schematic diagrams and write ups on the web BUT... If youve read that grid tied systems cant have batteries you need to be a bit more choosy where you get your info as that is wrong. Make sure you are looking at systems for the UK market as our rules differ to other countries. Have a look at "Solaredge storenergy" for a DC coupled hybrid system. Have a look at "Tesla Powerwall" for an AC coupled battery pack. Lots of other manufacturers, but those two have good schematics.

No. Both the grid and your inverter feed your consumer unit and the power from either or both feeds the house circuits fed from the consumer unit. Your inverter is connected to an MCB(maybe fuse) in your consumer unit in the same way as all the other circuits in the house. The difference being during daytime power flows from the inverter TO the consumer unit rather than power flowing FROM the consumer unit for all other circuits. At night when the inverter isnt generating, a small amount of power flows TO the inverter. None of the circuits are connected to the busbars

Absolutely not. It MUST shutdown or it could electrocute someone trying to repair the cause of your power cut

If Octopus are supplying you, then youre connected to the grid. If your inverter is connected to the consumer unit, then its grid tied. Anytime your inverter or batteries cant provide the power you need, the extra will be drawn from the grid

Whether its worth it is entirely up to you then. Depends on how much, if any, ROI you want, when your gonna move in, how easy to charge your EV etc etc

Op wants power in a power cut and is already talking about a Powerwall which will provide power in a cut but wont process PV, so 2 inverters. Im not sure if theres any UK certified systems that will do backup and process PV?? I think Solaredge already have PB/backup inverter certified for the US but not the UK yet. May be there are other systems??

If its a DC coupled battery then the batteries output comes through the inverter and is limited by the inverter. If you go for an SE3680H, the DNOs limit, with an SE battery then the PV and or battery output to the house/grid is limited to 3.68kw. Your DNO wont care if the power is coming from PV or battery, so long as its limited to 3.68kw. You can have as much PV or battery capacity as you want so long as the inverter limits output

As a holiday let is it part of your property and on the same supply as your house, or on a separate supply? Our original 4kw system was modelled at 3400kwh/year and has done 3500-3700kwh/year since 2015

Are you sure they said 3.68kw of panels?? DNO is usually only interested in the inverters max output and does care how many panels you have. Its more usual for DNOs to say you can have an additional 3.68kw of export which is governed by the inverter you choose. If that is the case then an SE3680H can have 5.7kw of panels connected to it, more if they are facing differing directions. Whats the maximum additional kw capacity you could get on your roof in each direction, including the FIT system panels?

Youre only tied to SE if you want DC coupled batteries. AFAIK you can have AC coupled from any supplier

Yes, but thats what youve got now with your 5kw inverter limited to 3.6kw. Using the correctly G98 certified inverter saves you the G99/G100 application and cost

Technically all correct, but.... With only 4.5 kw of panels youre unlikely to cause anyone any problems so I wouldn't rush to disconnect. Id ask youre installer why he installed a 5kw inverter as a quick look at a Solis 3.6 inverter says it can have 7kw of DC input. Fitting a 3.6kw inverter would keep you within the DNOs G98 limit and you wouldnt have the issues youre asking about. If you want to keep the 5kw inverter then youll likely need a G99 application with a G100 supplement to cover the export limitation. Our DNO charges to witness the export limitation is set correctly! Id put this back to youre installer to answer a few questions!!