Dillsue

And Ill ask yet again, how are you going to prove that? All the DNOs want is a bit of dialogue with you to ensure that your claimed safe system is actually that.

What! The vital service that everyone enjoys is a grid connection and the ability to use electric when they want(importing). Having a PV system connected to the grid isn't a vital thing to have, it's wholly optional The last thing any of us want are free spirits doing their own thing, circumventing the rules and connecting unapproved equipment to the grid. If you dont like the rules go off grid and do your own thing. Remember that a typical PV install is £1000s so a G99 application at £0-300 is peanuts

The DNO is interested in safety of the grid, which includes controlling whats connected to it for the benefit of everyone. You might see them as a pain in the butt but consider a couple of scenarios that G98/G99 ensure dont become problems. One of your family needs sensitive medical equipment and has some in the house. Living down your street are a load of reckless PV cowboys who've connected 10s of KW of PV without giving a hoot about what it might do to the neighbours medical equipment. Sunny day in June and the cowboys PV export pushes the voltage way past the UK limit and your medical equipment shuts down. Another scenario. Same PV cowboys install cheap Chinese inverters that aren't type tested and no one checks because theres no G98/G99. Turns out they dont actually disconnect from the grid when theres a power cut. Come the first daytime power cut and the repair linesmen find theres still 240vac on the faulty lines because of the PV cowboys inverters. Despite having the option to earth the live lines they decide to investigate the source before making a repair. The power is off to your house for significantly longer than it need be until they find the PV cowboys non compliant inverters and shut them down. Both hypothetical scenarios but you'll hopefully see that theres more to G98/G99 than DNOs just being awkward

Would that be buried in insulation? What would the voltage rise at the inverter be if the house was running at 250vac and the system was upgraded to 3.68kw? Without us knowing install characteristics its probably prudent to let the OPs lad size the cable.

Plenty of clarification so far. I would install a larger than 2.5mm cable if theres a chance you or someone else might expand the system in the future. You also need to consider the no load voltage in the house. If its already high you don't want a smallish cable creating too much of a voltage rise and pushing the inverter voltage over the 253v limit. Your lad should be able to calculate cable size for you.

I dont think you would need to send a fresh G98 for an inverter change as your staying within the G98 limit that youve already notified them of. Youre probably obliged to let them know about the change so just email them a copy of the ENA type test cert for the new inverter. As you say, additional panels are on the DC side with export limited by the inverter so the DNO isn't bothered. MCS is a different matter! There were some changes to the OFGEM rules in the last few years. For a FIT system you can add panels but will only get FIT payments on the original FIT registered TIC. So if you had a 4kw system and upped it to 5kw, youll get paid 4/5 of whats generated. If youre on metered export the additional panels need to be MCS installed to get paid for export. You can install extra panels yourself but can't get export payments, for the extras, without an MCS cert. Seems that metering could get a bit messy if you want to mix MCS with non MCS install. I'm sure the OFGEM guidance will explain it all so Google it

If your connected to the grid with something that should have permission, then youre not "doing the right thing". The "right thing" is to submit an application, seemingly with some DNOs not charging. If you are actually doing the right thing then your application will get approved.

The connection to the grid is electrical work so put down the name of your electrician. Failing that your local building control is obliged to test any work you do if you ask and pay their fee. On my application I just put down self installed with test and inspection by *councils* building control. All accepted and G99 approved.

Any or all of those options may work but how are you going to prove they work if not done through a G99/G100?

How are you going to prove it? From conversations Ive had with our DNO the way that they expect you to prove it is make a G99/G100 application and they then come out and witness the limitation system, all chargeable!

A single 6kw install is probably undetectable but even if it was the DNO is probably not going to do anything about it. Fast forward 5-10 years when lots more people have done the same thing, some with permission and some without. Come a bright sunny summers day and the local voltage goes over the max limit due to all the PV exporting. When they look into why and find a load of unapproved installs they could send out formal disconnection notices and all those unapproved systems become useless. G99 is a straight forward process and once youve got approval youve likely got it forever. What's more it seems to be free to apply in certain areas so arguably a no brainer

Id not picked up on people being asked for a site layout so definitely worth checking

I think you maybe looking at the wrong form! It's G99 A1-1 that you want. Certainly for my application there was no site or location plan needed. To go with the form youll need a single line drawing of the house electrics and a type test certificate for the inverter which youll get from the ENA inverter database

That's sort of right but....... AFAIK its not G99 OR export limitation, it's always G99 and if you want to add in an export limition system its G99 + G100 If your panels and batteries can only produce 1kw and are hooked up to a 5kw inverter then a smaller inverter would avoid the need for a G99 application

There's been posts saying that some DNOs dont charge for a G99 so you may get lucky. SPEN, our DNO charged us £300. If you start installing a 6 kw system and your DNO says you can't have that much, youre going to be in a pickle. Speak to them before you start buying gear and they may give you an informal answer quite quickly. SPEN told us informally within a few days that we could double our output. Formal application took a couple of months to process.

If your panels are going on the front of the house, how much shading is that tree casting over your roof?

Call your DNO, the company that fixes blackouts, not your supplier

Before you go too far designing/buying kit, if youre looking at a 6kw inverter youll need permission from your DNO so probably worth speaking to them to check you can connect a 6kw system to the grid.

With batteries storing energy in a way that produces DC voltage, it's not possible to connect batteries directly to the AC grid. The energy from the battery has to go through an inverter to convert from DC to AC. It maybe that theres an inverter built into the battery pack or it maybe theres a discrete separate inverter, but there will be an inverter between batteries and the grid

So long as youve got an approved export limitation set up.......16amp for G98 OR whatever your DNO gives consent for under G99.

But only 50% of the population understand that principle

SPEN told us informally within a few days we were ok to double export from 16A to 32A. Formal G99 application was £300. Be concious that once youve got approval its unlikely to be withdrawn so youve got the "right" to export for ever. I'm sure it's been said in the past that some DNOs havent charged for a G99 application??

If discharge to the house from your 6.3kwh battery is limited by your 3kw inverter then doubling the battery capacity wont make any difference to the discharge rate of 3kw, if the second battery is connected up in the same way as the first. What's the objection to a G99 application for a bigger inverter?

You can have as much PV installed as you want. The DNO is only interested in what can potentially discharge to the grid which is limited by the inverter.

If its the one Ive just looked at its described as used and I'm fairly sure ebay expects a used item to be fully working unless any defects are stated. Andover is a long way from Preston so that would be a concern for me if I wasnt happy and wanted to return it.