I had an installer provide me with a 3kwp solar array and SolarEdge Inverter about 12 years ago. I get FIT payments for this setup - so Its already paid for itself but with the increasing cost of electricity I was thinking it would be good to add a battery to save whatever power I didn't consume and also look to charge the battery "off-peak" with one of the lower rate energy tariffs.
As I don't want to jeopardize the existing FIT, it looked like and AC coupled inverter and battery were the way to go. I am with Octopus Energy too and have considered an EV purchase to allow me to get onto their Go tariff.
I was looking at the Victron kit (5kwp) as one option and the SunSynk (8kwp) as the other.
I eventually decided on a DIY 48v LifePO4 battery along with the Victron Kit. So I have purchased the following:
16 EVE 3.2v LifePO4 cells 280Ah.
JK BMS (JK-B2A24S).
Victron Multiplus II 48/5000/70-50.
Victron Cerbo GX
Victron Current Sensor
I have built a housing for the cells so they are under compression and now am about to find an electrician (Part P qualified) to install the AC side for me.
I am aware that I need G99 approval from my DNO - SSE. And also aware of the issues that Victron have faced getting their kit re-certified and marked as compliant on the ENA type test register. I've not seen any G100 certificate for the newer regulations - so wasn't sure if one exists or not? (Sadly I see the Sunsynk kit is now G99/G100 compliant - so wishing Id chosen that route - given where I am ... but not certain these cells/BMS are a great match for that system).
I have been trying to build a schematic that could be used for the G99 application.
![Image](https://i.postimg.cc/V5JQgmRP/27-Quentin-Road-Version-1-3.jpg)
And was wondering if anyone could review this and add any value by advising what needs to change to make the install better.
I am looking for the Victron to provide backup power via one Consumer Unit which would power the majority of the house (I'm aware the loading would need to be kept light) in the case of grid failure.
In normal operation, I'd want any excess power generated by the existing SolarEdge to be absorbed by the battery. And for times of the year when there is very little solar, I'd want to force charge the battery on an off-peak tariff.
I want to allow for maintenance of the Victron Inverter - so have added AC isolation. And when this is out of operation I have added a change over switch to allow the maintained load CU to be powered from Grid as opposed to the Victron Inverter.
I've also added an earth rod. Don't know much about the differing types. But I understand for the Inverter to run in backup mode it does require a discrete earth. Is there anything specific I need to state for this aspect?
I've been trying to read lots of posts and gather info from others in similar circumstances and apply all that I think I understand. But at the end of the day I am a novice and want to ensure this is done properly. So, I really do welcome all constructive advice.
I still have a dilemma how to proceed. The Victron inverter isn't yet approved and its been like that for months now. So could I get the electrician to install everything but put it into "maintenance" - so that its isolated? Or is it best to wait for G99 certification? What would happen if I applied for G99 with the DNO currently? Would the application just get rejected? Can I set a commission date well in the future when certification might be available?
And what do folk think is the likely outcome as far as certification goes? Will this inverter ever qualify in the UK?
And the original install was done with G98. But that inverter is no longer supported. Would the DNO raise any issue with that? It certainly won't have a G98 certificate to match the current regs.
I think the "fast track" G99 route criteria has changed a bit too? But I'm not sure I understand the differences. Would my proposed amendment qualify for fast track now? It certainly didn't under the old fast-track definition.
My existing setup has 3kwp max - its a small (and old) inverter. And this can't be controlled by the Victron to explicitly control export to the Grid. So does the Victron need to be limited to 3kwp export? That would allow the SolarEdge to be working at full capacity and the Victron not to supply any additional power. Eventually I may like to add DC coupled Panels to the Victron Inverter via an MPPT charge controller. That would mean i could potentially charge up =more of the batter capacity via Solar rather than having to force charge the battery overnight (so keeping costs down). But for a lot of the year in the UK I doubt that would have a major effect and I would always have to rely on significant forced charging in Winter.
This brings me back to the G100 certification. I did see this in one of the old Victron documents somewhere. But I've not seen any mention of this more recently in the attempts to get the G99 certification approved. So if some grip limit is imposed should i ever get approval, how is this demonstrated or achieved?
Many thanks for anyone who is able to help me out.
Cheers all.