jimseng

Actually, re reading the manual I'm still trying to get my head around how to set an export limit, but I am getting there. Luckily I don't have kids. I'm not convinced I will let any into my new house. They are noisy, sticky things that leave jam and muddy footprints everywhere.

Not sure I fully understood this. Can you expand? When I briefly looked through the manual today it seemed you can set the export to any KW value, but it was a fairly cursory browse through. I'm talking about the Sunsynk 10 / 12k inverter. If I do want to try and export at some point Then it likely going to have to be the 2k limit under a G100 application with anything other than a G98 certified inverter.

Exactly. A 10kw Sunsynk and a 16kWh Fogstar battery is around £3.5k all in. That is a G100 / 2 compliant system. With the 60 amp pass through I think I would struggle to max it out, unless I really try.

Maybe. I'm a bit of a stickler for rules in case it comes back to bite me. If I got investigated it might become tricky. I'm open to all suggestions though. I will be using the grid power too, otherwise I would fit a battery charger and not connect the inverter to the grid at all, that would mean I wouldn't need to involve the DNO. I have thought about that route but I think it would be a bit limiting in the winter. I must admit I haven't done the maths yet as I'm not sure how much battery power I will start with.

That isn't how I understand it. My understanding is that to even fit an inverter that is capable of > 3.6k export, even if it is set to export nothing requires a G100 application and maybe even a witness and password to prevent the settings from being changed. Or a G100 limiting device between the meter and the inverter (costly from what I have found). If I am wrong then that would simplify everything. If there is an inverter that is incapable of exporting to the grid then I expect that would work. There is a Victron option of a 5Kw set to 3.6kw in firmware from the supplier, and therefore G98, but it then effectively becomes a 3.6kw inverter, all be it with a higher grid pass through, which, to me, seems pointless.

Do you mean there was a fee to Octopus to allow you to get paid for a non MCS approved install? The whole energy supplier side of things is another bit of research I have to do as I don't even have a DNO connection yet. Sometime in the new year.

That is a question I have mused over. Passing the ac output of the G98 device to the ac input of a slave device set to zero export. Or a generator input. But in order to live with the system, a high ac passthrough is important to me. I don't want to split my loads into on and off grid if I can help it. That is why I am looking at a 10kw system for an all electric house. 3.6kw isn't enough for my long term ambitions. I should add that grid export is not relevant to me as it is a a self install. Off peak battery charging and lots of battery capacity is important.

You're right. There reason I asked the question is, first, I was feeling grumpy at the notion that we are supposed to be moving towards net zero and yet [insert political point about Britain, privatisation, consumers trying their hardest to do their bit by investing in energy efficient homes and still having to contribute their own limited finances towards the under invested national infrastructure], so I was thinking about ways round it. And the second is that actually, it is quite hard to find a hybrid inverter that ticks the G100 box and is compatible with 52v batteries (for instance, the three you mention above are all incompatible). I had struggled for a while to find anything that fitted my criteria (cross referencing the ENA database with datasheets can be a bit bewildering for a newbie like me). But I think I have found two candidates now, A Growatt and Sunsynk. I think I am favouring the Sunsynk at the moment simply due to the AC passthrough current, but they are a little bit more expensive. I did ask the DNO how the 2k limit fitted in with a G98 application. His response was: "The rules get a little complicated you are correct under G98 you can install up to 3.68kW per phase on a fit and inform basis, once you get into G99 things change NGED can restrict exportation to limits that don’t have an adverse effect to the network so effectively the 3.68kW rules does not necessarily apply." Part of me wants to do a G98 application and see if they are forced to upgrade. I am actually writing a letter of grumpiness to Ed Milliband, but I doubt he'll even read it.

Thanks JohnMo. Simple is indeed best. I'll take a look at your suggestion.

I have been struggling to find one that suits my battery choice. I have been on the ENA database and for some reason I am having difficulty. I don't know if I am using the wrong search terms. I found a Growatt that seemed like a good fit but I can't track down a G100 certificate and the Growatt UK distributor neither answers the phone or responds to emails so far. It is proving harder than I thought it would be. It seems the G100 part of manufacturers literature is a low priority so they don't advertise it much.

I was actually asking if bypassing the whole G100 limitation, and the costs involved, by keeping the inverter off grid is a good idea. I am installing 10.2k of solar and planning on as much battery storage as I can afford. To me, being able to choose whether to run things like the cooker, immersion, heat pump off the grid or off battery/solar gives me more choice. 4 pole contactors seem fairly cheap in the grand scheme of things, and easy to control. But the main thing is my pathetic G100 export limit. If I can avoid jumping through that hoop that is a win for me. I assume I don't even need to mention anything to the DNO?

Ok. Thanks. So here goes... good idea or bad idea? (Runs for cover).

Hello. Here is a simple question, Given that I am limited to 2kw export and G100 application if I go down the grid tied inverter route. Is there any legal issue with keeping the inverter purely off grid and using a 4 pole changeover contactor to switch some loads to grid if needed. The inverter would not then be connected to the grid at all. Do I even need to tell the DNO what I am doing? I'm only interested in the legal side of things, if we can keep strictly to the question. Whether it is a good idea or not is for a different thread perhaps?

That does seem the best solution. The Growatt I mentioned above seems to fit the bill. I have no idea if they are a good make but on paper it works.