Dillsue

Under the FIT scheme youve always been able to replace components on a like for like basis but OFGEM changed the rules in 2021 so you can change more or less what you want including increasing or decreasing the installed capacity and still retain your FIT payments on the original capacity

Margins are likely not just to reduce uplift but to save disturbing the perimeter of the roof. Trying to lift tiles/slates near the ridge and or gable verge is difficult without disturbing things. Even in a sheltered location where could go right to the edge life is easier with a verge around the array. It also gives access up the side of an array to get to the ridge or top of the panels, if youve a head for heights!!

I think Solaredge have ditched the fire extiguisher in their current batteries. Don't know if they've changed the chemistry or just a bit more confident??

Place the mounting slab on casters so its "mobile"therefore temporary and nowt to do with planners

Other than not retro fitting a smaller system than is alresdy fitted, thats all pretty vague 3 paragraphs!

I think/hope you already know this but G98 restricts your inverters export capacity, not the size of the array. Within the inverters limits, put a bigger array up and your G98 inverter can sit at 16amp(3.68kw) output for much of the day. Don't switch big loads on at the same time and there's not much in a typical house that will need more than 16amp.

Ours displays RED too on account of the not so small ammount of export. I read somewhere a bit ago that your style of meter(ours to) actually records energy flow in both directions but can only display one figure. I have it in my head that there is a way to display the second figure but can't remember how to change it or where I read it!!

Interesting. Would that be a standard dumb digital meter wired in reverse??

I assume that you meant why cant your INVERTER charge and discharge simultaneously as in charge the battery and feed power to the house/grid/PW, which it can.

You don't need an installer to submit a G99, in its straight forward to do yourself. If you want 7 kw to use in the house then apply for 7kw and see what they come back with. If its a no then you can- Ask then to reinforce the grid so you can export 7kw Implement an export limitation system Use the 3 phase supply youve got

The inverter does limit all throughput but it matches its throughput to the house load. It monitors the power leaving the house and as soon as it sees export go above the limit it's been set to, it throttles the throughput so that export stays within set limits. Yes you can export 3.68kw on each of the 3 phases without getting permission via G99. With 3 DNO fuses Id guess youve got 3 phase to the house but the house is only using 1 phase. Youd need a new meter and a new consumer unit to hook up the 3 phase. Except for the meter, your spark should be able to sort out the rest. If youre only looking for 7kw export it would likely be easier/cheaper to stick with single phase unless SPEN object

We've got the same DNO as you, SPEN, but likely a different engineering office as we're in N Wales. We had informal agreement to double our export from 3.68 to 7.4kw within a few days. Formal offer took a month or 2 but nothing like 9 months. Definitely speak to them as theyll likely be able to give you an idea of the export theyll allow over the phone. If you are constrained by what you can currently export, theres 2 things to remember. First you can have a big system with export limitation so you could have an inverter/batteries that will feed 7kw to the house but is limited to 3.68kw to the grid. Second is that the rules on who pays for grid reinforcement have just changed so if theres export limitation because of grid capacity, the DNO pays for upgrades whereas previously the customer often did

I wasnt suggesting that you get your installer involved with the DNO but just to get a second opinion that what you want to do is ok. Armed with confidence that there's no reason to object then formalise the complaint. It doesn't cost anything to complain to the energy regulator so even if you "lose" youll be exactly where you are now If youre happy to go with an SE battery then discussion over the Powerwall is academic. It's £7k ish for an SE 10kwh battery vs £10k? for a 14kwh? Powerwall. I have an inkling that a Powerwall has to be installed by a Tesla installer so there's mandatory install costs with the PW

If you really want a second Powerwall maybe ask your installer and Tesla if theres a reason they can see for the DNOs objection and if not, make a complaint firstly to the DNO then to OFGEM. DNOs arent always correct in what they say! When we applied to add a second 3.68kw system to the 3.68kw system we already had, the lad that was doing the intial assessment said we would need to have export limitation on the new system. It took a few emails before the penny dropped that the second system was inherently limited to 3.68kw. We got approval despite initial objection/confusion.

My guess would be because 2 powerwalls isnt really a problem??

Maybe let Tesla know then as your DNO citing 2 Powerwalls as a problem might be of interest/concern to them

Did you tell them that you would set the SE to zero export to keep total export under the limit you already have? I understand that Tesla specs include multiple Powerwalls for the UK market so there's some disparity between what your DNO seems to be saying and what Tesla are saying.

There's no difference between a 3.68kw Powerwall exporting and a 3.68kw SE inverter exporting. If you disable the SE inverters export and replace it with a second Powerwall theres no difference to the grid as its still 8.7kw total. When you asked your DNO about adding a second Powerwall(3.68kw)did you tell them you are disabling the SE inverters export?? If it's more storage youre after then go for the extra SE battery. If you want more power to the house then adding an SE battery wont make any difference as your SE is limited to 3.68kw

You've already got consent for 8.7kw export so configure your SE inverter to zero export, existing Powerwall to 5kw and new Powerwall to 3.68kw. Max export will be what it is now and youll have 5+3.68+3.68kw to use in the house. You'll likely need to do a G99+G100 application. I think youve already got a SE energy meter so SE configuration will just need the export limit setting, but check your inverter has a G100 certificate Simples

PW spec says 5kw sustained 7kw short bursts so may be worth checking they dont mean collective export is 8.6kw when SE is at max?? There wasnt a note at the bottom saying you got what you want but warranty is now void

But the vast majority of EV charging will be from the grid. I assume/hope that any PV input into the charger will be downstream of the meter??

Inverter sorts that out. AFAIK theres a comms link between the inverter and the batteries with each battery pack having a charge controller. Black magic takes place and you're batteries get charged. If its an SE3680H inverter youve got even with 30kwh storage youll still be limited to 3.6kw from the inverter

And........ I beleive the next generation of EV chargers is mandated to have smart meters built in. I suspect as a minimum the correct rate of VAT can then be charged?? Could also be used for remote disconnection at peak times??

You can have 3 SE batteries according to this https://www.solaredge.com/en/products/residential/storage-and-backup/solaredge-home-battery-400v

Solaredge allow significantly more oversizing than 20% with a 3.6kw SE3680H accepting up to 5.7kw DC input which is 55% oversizing. Split the panels over differing compass points and you can have much more.