Dillsue

I'd take a step back and sort out your design and inverter before you start wiring. Youve got panels over 3 differing compass points so they will be generating at differing times. If you wire them all together they'll likely affect each others generation at differing times of the day and you'll not get the best out of them. You may also be over the inverters max input voltage. You'll likely want to wire them in 3 groups, one for each group facing the same direction. Each group will need its own MPPT input on the inverter. I'm not saying you should use a pro installer but the £6k quoted will likely include design and a warranty that things work, as well as installation. There's more to an install than the materials you've mentioned- inverter, isolators, meter, connectors, elec certification, DNO paperwork, crimper, connection to CU. Assuming you're grid tied, have you got DNO consent to connect a 12kw system. Hopefully your installer had included to sort that out??

You mentioned previously that your main priority is ROI so you need to work your own figures and do a load of research. Plenty of discussion on battery ROI and to me at least its not clear cut that batteries make financial sense. If you go down the battery route and are constrained now, then design your system for how you'd like it to be and ensure your design allows for expansion when funds allow. Have a look at Enphase for micro inverters and Tigo/SolarEdge for optimisers as they all explain the advantages over conventional string setups. Disadvantages are additional cost and access for replacement if they fail but that's only applicable to roof mounted systems and likely won't apply to your ground mounted system. You can avoid some of the extra cost by buying surplus kit online- Solaredge optimisers can be had for £20 new rather the usual £50-70 but don't rush into buying until you understand what you are buying.

Be thankful you got the right letters and in the correct order. It was the thought of another bollocking that reminded me to add the "h" but doing 1 fingered caps on a tablet is a few keystrokes too much

Whether a 3.68kw inverter makes better sense than a 5kw one only you can decide. Sticking to 3.68kw means you could install under G98 and avoid the G99 application fee for a 5kw inverter- £300 fee for us in 2022. Down side is the peak generation from 5kw of panels could be lost for a small amount of time but if you are charging DC coupled batteries then you won't loose so much as you could be charging your batteries. How have you decided on 5kwh of batteries? As mentioned above and on the other thread, you need planning for an array over 9m2. If your array is hidden from view that might not concern you. If you want a flexible system then you can't beat micro inverters/optimisers for facilitating add ons and also allowing different wattage panels to be used in the same string. They'll also improve generation if you've got partial array shading

If that's the probe that's controlling the hot water, which it probably is, it seems obvious that with it near the top youre only going to heat the very top of the tank. It's hard to understand their rationale for putting it there especially if you queried it! If you've also got issues with the heating I'd be tempted to get some body competent in to check the whole installation over.

If 27c is the limit of the glue, could you not use a floating floor

If you avoid switching multiple loads on at once there's a fair chance you'll be able to stay under 3.68 kw for most of the time, but it can take a while to get into the swing of not switching everything on at once- 18 months for my wife to sort of get it!!

Yes you can and its straight forward- download the form and see what info you need. You'll likely need to supply a single line diagram of your house distribution but Google it and you'll likely find something you can doctor. If you installed without permission, you'll be breaking the terms of your electricity supply contract and the national terms of connection which I think are legally enforceable. A G99 is straight forward so why would you want to not do the right thing. No ones going to check up on you unless there's a problem. If you go for a 3.68kw G98 inverter instead of the 5kw one, then all the G99 paperwork, and fee, go away but you'll likely be drawing on the grid more often than with a 5kw unit

Incoming and outgoing capacity aren't the same. Fair chance you've already got the incoming voltage set fairly high to allow the DNO to get as much power round the grid without upping the current and requiring expensive bigger cables. When you draw 50amps from the grid it pulls the voltage down which isn't a problem if you've already started with a high supply voltage. When you try to export 50 amps it pushes the house voltage up and if your starting no load voltage is already high, your 50amp export will take the house voltage over the 253volt statutory limit. More importantly it might take your neighbours voltage over the limit which is a problem for the DNO. If you're on your own transformer it may give you more options but anything shared or potentially shared in the future and your likely stuck with the DNOs std policies

Not sure if NG publish such a thing but SPEN have online heat maps of their distribution networks showing where they have constraints for new connections(not domestic size systems) For each section of the network there's a contact email address so I just emailed that address and outlined what I had in mind. A junior engineer phoned me 2 days later, having already looked at the network serving us, and we agreed things over the next day or so. Formal application followed just to formalise what we'd already agreed. If your looking primarily to maximise self consumption then you may be best to go for a big system with export limitation as pushing the full 11kw down a single phase is quite a big ask. Its difficult to see how NG could say no if you implement export limitation and are prepared to go to zero for the addtional array and exporting only the existing 16amp

A G99 application is straight forward- download the form and have a look but there's a fee to pay. Our DNO(SPEN) was happy to look at an informal enquiry and we agreed our export limit by email/phone and then did the formal application. If you are tripling your array to 11kw remember that it's the inverters output you declare to the DNO, not the size of the array. You could hook up 11kw of panels to a smaller inverter and apply for the smaller inverters output. If you'll use all 11kw in the height of the summer then you could always go for an export limited system and do a G99/G100 application. That way you'll have the full 11kw available for self consumption but export as much or as little as your DNO will allow.

I guess it would need to be so it could power the critical loads/charge the battery from from the grid when there's no PV??

That's a grid tied set up with back up. The grid tie is the AC connection coming out of the bottom of the inverter then running to the left out towards the grid without any means of automatically disconnecting from the grid. If the grid goes off so does the inverters output to the grid and the consumer unit, so the consumer unit is dead. The inverter you are showing has a back up output for critical loads but needs a grid connection to operate fully ie power the loads off the main consumer unit. If the outbuilding supply came off before the CU, then its protected by the DNOs service fuse so a fault in the outbuilding would take out the service fuse(or fry the cable) and black out the house, likely for a long time until the DNO got out to replace the fuse. If you add your own fuse/mcb to protect the outbuilding cable then you might aswell have the outbuilding supply coming off the CU and not before it.

The OP is trying to avoid running another cable out to the outbuilding. If the existing is used for the PV DC therell be no AC supply to the outbuilding That's the way all grid tied inverters are connected as they shutdown when they loose their grid connection.

If you've paid a deposit to the kit designer, I assume you have a quote based on a fairly detailed spec. Fair chance you'll be able to do a pretty accurate heat loss calc off the spec/quote and know if an ASHP is in the running

Some things to consider- As ProDave mention volt rise could be an issue but you can mitigate it. Some inverters allow you to reduce power generation as the voltage rises. If you are happy to do this then pick the correct inverter. As loads are switched on in the house the house voltage will likely drop a bit so when measuring your base voltage do it with 1, 2, 3 and 4kw loads switched on to see how the base voltage varies at different load levels and the likelyhood of the inverter power throttling. If your no load voltage is less than 244vac, then likely you've not got a problem with voltage rise. If you've got a battery to charge that's local to the inverter then voltage rise may not be an issue if you are routing power to the battery and not down the SWA. As TonyT mentions, to charge your battery when there's no load demand from the house you'll likely need a CT on the supply leaving the house and need to consider how the CT signal will get from the incoming supply to your inverter/battery. You might be trenching If your battery is AC coupled then how are you going to limit the current that flows down the cable from the inverter and battery. If your battery is DC coupled are you sticking within the 16amp G98 limit. Ground mount PV has planning restrictions and I think you are limited to 9m2 without getting permission. You may not be concerned, but worth knowing the limitation. If you might extend the array in the future then base your design on the extended array size/location

As the client, the level of insulation and air tightness is up to you. Get your head round your energy saving options and tell your architect what you want- build to passive house or building regs or somewhere in between, but it's your call

You asked if you could use the existing SWA or needed to run another one and the answer is you can do either. Concerns over distance from the incoming supply for monitoring wasn't mentioned but why are you considering a dedicated SWA if you think the shed is too far away??

Connect wherever you like so long as you consider circuit protection, discrimination and voltage rise when the inverters at max production.

Sorry I read another thread and replied on yours!!!! Ignore me

If your existing inverter is a 3.6kw unit and you're thinking of adding micro inverters to the garage you'll need DNO permission. If you want to avoid DNO permission you'll need a single 3.6kw G98 inverter and wire each of the 3 arrays to its own mppt input, or use optimsers. If you're going down the DNO route then it's likely cheaper to install a dual mppt inverter in the garage, where your big loads are, and split the east and west panels over the 2 inputs. If the existing inverter has dual input then move that to the garage and get a basic 2 kw inverter for the house.

Quick Google search says Enphase IQ8s will handle 560w panels. Avoid the junction box if you can which should be doable with micro inverters.

If the garden room panels are on an east/west split the you'll probably want the east and west arrays on separate strings so you'll need 2 spare mppt inputs on the inverter and 2 loops of cable running down to the garden room. The mix of directions and shading would make your set up an ideal candidate for optimisers/microinverters

The prices you've highlighted are 2018 and 2021 prices. May not be quite the same as we've got now??

Maybe you are looking pre 2023? Just scrolled through what I think we're the N Scotland figures for 2023 and I could only see one instance from 1/4 to 1/10 where it went just over 24p. If you go beyond 2023 then you've got all the turmoil of the start of the current energy crisis