Dillsue

Assuming your existing is a FIT system?, look up the OFGEM guidance for FIT generators and either the guidance for generators(you or me) or FIT payers(electric Co.) includes schematics on allowable configurations for battery hook up. Basically it mustn't be possible to charge the battery from the grid and then discharge through the FIT Generation meter. Only site generated eleccy from your acredditted system can pass through the generation meter. DNO requirements are separate so an AC coupled battery downstream of your generation meter will likely meet with FIT rules but need G99 approval from your DNO

When I looked at the Octopus non MCS scheme you needed BC sign off that your roof is structurally able to take the extra weight and you need a part spark sign off. Potentially £500+ for those on top of the Octopus fee. Member if youre buying secondhand inverters to make sure they comply with current grid standards, if you want your connection to be legit

Yep. A PV diverter will do that for you. Ideally you want 2 immersions in your tank and a diverter that will heat the top of the tank first and switch to the bottom immersion when the stat in the top one switches off.

For export limitation, G100 requires the limitation to be password protected by a factory or installer password that the user shouldn't have! If you go for an inverter over your DNOs 5kw limit you'll need one with a G100 cert and professionally installed to comply. No idea if your DNO is bothered with such things?? Our DNO said if we went for export limitation they'd want to witness it and charge several hundred £ for the privilege If you go with a 5kw inverter with a G99 cert that should limit to 5kw but check the cert. I don't know about other manufacturers but Solaredge allow up to 200% DC input of the inverters rated AC output so an SE5000H can have 10kw of panels connected

Yep, with the right setup. If your battery is DC connected and your inverter carries a G98 cert then good to go.

I may be wrong but for your export I think Octopus accept manual readings where smart meters won't connect. They're obliged to pay SEG rates so if a smart meter isn't sending data, manual readings is the only way they can meet that obligation. Doesn't help with variable tariffs though!

Your azimuth figure should be -30 for a SES facing roof but that's not going to make a huge difference. Remember that to use PV, without batteries, you need to use it when the sun is out and generating. If you or your guests are out during the day and back in the evening to cook/wash etc then you'll be exporting lots of surplus PV during the day and importing in the evening. The only way to more accurately compare your usage with forecast generation is to use hourly figures.

Top of the quote says 10.9kw so probably just cut and pasted from previous quote

No apology needed. From lots of posts it seems that DNOs across the country do things slightly differently and I just wanted to see if that was another DNO quirk

Not sure if your talking about the limits set by 2 differing organisations. The 16amp limit is set by the DNOs and as you say is governed by the inverter. OFGEMs FIT scheme looks at generation capacity which is the capacity of the panels

AFAIK you can only change like for like so if you've got 13.4 kwp now you'd need to replace with the same capacity. If you want to do something different then read the guidance to understand what total and net capacity means and how it would affect payments.

Absolutely

I know of 2 people that put self installed and had it accepted without a part P sparks test cert- did you submit the electrical test cert to your DNO??

OP is doing a G98 notification so G100 is irrelevant as G98 already requires a set limitation

If you've got 13.4kwp of panels, run your figures through PVGIS to see what you should be generating. If you're around the forecast there's no point in changing your panels. Our 9 year old 250 watt panels are generating like new.

If you increase the size of the array it'll generate more over the year. May may not be clipped in the summer but total annual generation will go up. Whether your FiT payer notices or cares is anyone's guess.

Same for us

Put your sparks details in the installer section and include the inverters reference off the ENA type approved database in the inverter section. Include a single line diagram of your house electrics with the G98 form. Job done Do your sums for getting export payments from Octopus remembering that the 15p/unit isn't guaranteed.

Google FIT Guidance for Generators and look at the section on alterations- that's the OFGEM guidance which is the horses mouth

If you swap out the panels like for like ie remove 12kwp and install 12kwp then you don't need to notify anyone. Its only if you change the capacity that you need to notify your FIT payer. If you don't think your array is generating correctly you probably want to investigate that rather than shelling out for a new set of panels. Our FIT system from 2015 is still generating like new.

Your DNO always needs to know about generating equipment connected to the grid, no matter the system size For PV, if its under 3.68kw max export to the grid and you're using a type approved inverter, notify them after installation using a G98 notification. If its over 3.68kw max export, you need to get your DNOs permission before you connect using a G99 application.

Can't your spark size the cable for you? He's gonna be signing off the install so getting him to spec the cable should minimise any problems.

Nope. Just adding balance to some of the stuff your saying

I think so too, but they could also be any UV stable cable tie wrapped to a length of fencing wire. Or run inside some 20mm conduit tie wrapped to the wire. Lots of different options

Doing 'your thing' is great but you're in somewhat of a niche and, in my opinion have some fairly extreme views, like suggesting manufacturers techs would maliciously access your inverter. I've got personal reasons for countering much of what you've said to hopefully add some balance to your post, so hopefully you'll understand my persistence. It's a public forum and people are influenced by stand out statements. Hope you find the optimiser data buried somewhere in the Modbus info.