Dillsue

I think there was someone on the green building forum who was getting paid for both FIT and SEG for two different systems. I think they had to give up the FIT deemed export payment and take a flat unit rate for all metered export. Still got the FIT generation payment based on the generation meter reading. I think this was the set up but have a trawl round GBF to be sure

No doubt thats the case for you but the OP is somewhat different in that hes still looking for concept design. If DNO is only considering a 9kw array and no batteries then DNO may have given informal approval without considering a potential doubling of export with AC coupled batteries?? Maybe the OP has agreed an export limitation system or exporting via one or more G98 inverters?? Be good to know the basis of the "approval" for a 9kw connection.

If you dont know the system design/inverter model, are you sure you have approval to connect a 9kw system to the grid? Even for informal "approval" I had to email and discuss the system I had in mind to get informal agreement before I put in the formal G99 application. If youve already agreed some aspects of the design such as export limitation you probably want to post the details

Thats a handy forum

The VAT notice only refers to PV panels, cabling, control panel and inverter. No mention of batteries so I dont know if they should be zero rated even if installed with a new system?? Probably want to refer the guys charging VAT on the materials to the VAT notice??

VAT notice 708/6 seems to suggest temporary zero rate is for labour and materials

Worth checking where all the weight is going to be. I dont see any structural grading stamps on any of the timber(c16/c20 etc) and a quick peek at floor joist span tables says 7x2 is good up to around 4m, when graded timber is used.

Forgot to mention youll not get much PV contribution to running the HP in the depths of winter when generation is lowest and demand is likely highest

Just check that the installer is fitting a G98 compliant inverter that will limit output to the grid at 16amp. Thats the limit the DNO sets for fitting systems without prior approval. Certainly with solaredge you can connect 5.4kw of panels to a G98 limited inverter

Thats sometimes true, but winter alone isnt "much if the year" I tested 3kw of panels in feb this year propped up on the ground facing south and they were generating 2kw on sunny days

Unless youve got an automated excess generation consumption system(batteries/pv diverter) youll likely always have excess, unless youve got a relatively small system for the size of your house base load. Most of the significant household loads are intermittent when they are running so even if you stagger appliance use there'll be lots of periods when an appliance is running but only using a small amount of generation with the rest going to grid. A washing machine for instance only heats and draws a big load for a small proportion of the wash cycle so when its not heating any excess not used for base load in the house will go to grid.

Thats a great option if theres no spare higher roof space but check the track of the sun and see where abouts stays in full sun for longest. Weve just put in a 3kw ground array with a further 2kw to go on the ground but realised that where the 2kw was planned to go gets shaded way before a spare bit of the main house roof does. The 2kw is now going up on the roof where it gets an extra hour of direct sun. The orientation isnt ideal but when comparing hourly figures from PVGIS at the time of day we want the extra production, the seemingly poor orientation doesnt make much difference.

Within the FIT scheme youre only supposed to change things on a like for like basis ie replace a 235w module/panel with a 235w(ish) new panel. Adding optimisers is a system design change and would likely need approval from your FIT payer. We have a FIT system with optimisers so they are a permitted bit of kit but a retro fit probably needs approval and fitting by an MCS accredited installer. Sums probably wont add up so maybe best to keep the panels clean and the trees pruned as best you can.

Pretty sure smart meters are free so no harm in asking for one to be fitted, if thats what you want. As you say, if your solar isnt generating enough power for what the house needs then any shortfall is drawn from the grid and your import meter records the top up youve taken. Conversely, if your solar is generating more power than the house needs then any excess flows into the grid and if youve got a smart meter the export meter records the excess thats gone to the grid to power your local hospital/school/cannabis farm off green eleccy.

You dont need a smart meter unless you want to go for an MCS install and claim SEG export payments. Your "outside box" is your meter box. If you want to connect your solar inverter to the consumer unit in the man cave, youll need a slightly larger one to install another MCB for the solar inverter to connect to.

If its a flatish roof youll need mounts to angle the panels which have to be spaced out so they dont shade each other. Youll likely get fewer panels on the roof than if it were the same area on a pitched roof. Go to your local planning web site to find out if theres any planning restrictions You dont need to tell your electric supplier youre fitting panels unless you want to claim SEG Post a photo of the "outside box" and maybe we can work out what it is

Have a look at your contract with your electricity supplier and I think youll find it includes a reference to a "national supply agreement" or something similar that governs your connection to the grid. Youll likely find something in there. Edit-It National Terms Of Connection that you want

First sunny summer day after some of Wil's neighbours have installed G98 systems or bigger systems without permission?? Our TX is 5Kva just for our house and is getting replaced at the DNOs expense. When our G99 went in they could easily have told us we needed to pay for the upgrade but they said it was under specced by modern standards so they would upgrade it and lower the supply voltage at no cost to us. Couldnt have been more accomodating. The problem with circumventing the rules is if problems start to happen on a section of the grid where theres unauthorised systems, the DNO will investigate and the unauthorised systems will get disconnection notices. It maybe that the problems have started because neighbours have legitimately added G98 systems but it will be the unauthorised systems that get the disconnection notices and may have to pay for network upgrades before they can reconnect!!

Thats more like it. Hopefully theyll informally give you some idea of the local constraints and what youll likely be able to connect.

Im not questioning whether things can be physically done, but trying to understand the process that you are using to do things, above board. I took your previous posts as saying that you could put in an export limited system(zero export) without using the G99+G100 application process. If its not through the G99+G100 route then intrigued to know what other routes there are to legitimately connect to the grid??

Yep, an empty garage is probably a better bet but that would be the place for any battery pack, in my world anyway. I had another look at PV connectivity when using Storedge to charge from another inverters output and I dont think you can do it so definitely check with SE before making any decisions, if you can get your head round the cost!!

Maybe theyve seen the thread on parasitic load and are off loading Ecodans before word gets out and they become unsellable

Our DNO was happy to discuss technical detail and I think/hope we agreed the scheme that our G99 application has formalised. Cant speak for UKPN but SPEN were great, so far. Ive no idea what other manufacturers offer but have a look at the SE Storedge system to see what is possible... charge from PV, charge from the grid, charge from another inverters output all on DC coupled batteries so they dont add to potential export figures.

As the OP already has a FIT system thats likely to have been declared as being at the 16A allowable export limit, surely the DNO is going to be asking questions if you send in another "statement of compliance" without a G99 application or manufacturer declaration of zero export? Have you actually done this and had it accepted?

Still needs a a bit of G99 begging for the inverter unless the new system is off grid