Solar system design

[dan_b]

Hi Brave Knights of the Round Table
My friend is doing a self-build, and is getting to the part where he's looking to spec and install some renewable generation.
The south-facing aspect of his roof is essentially unlimited size - 9m x4m!
He also has a 3-phase electricity supply (the plot was ex-light industrial)

I have offered to help him get the right kit.
He'll also have an Air Source Heat Pump which he plans to use for space heating and hot water.
He has an EV, so will want a car charger, and he's also keen on getting a stationary battery for the house too. He wants to be as grid-light as possible.

Given it's a self-build, and there's no FiTs anymore, I guess he can do a DIY installation and not be too concerned?

Was thinking 9kW or 12kW of solar - so 3 or 4kWp on each phase?
With that size roof I guess go for the lowest cost £/W panels rather than gunning for Ultra high power ones?
Any good 3-phase SolarPV inverters out there?
Thinking a "Hybrid" inverter that could also control a battery system
A Zappi for the EV
And a PylonTech battery system ?

Do I actually suggest to him doing a split array rather than sticking it all on South?

[Oldgreybeard]

For a new build it's a no-brainer to fit a roof integrated system. Saves on the cost of roofing, looks a LOT neater and if properly installed is as well, if not better, ventilated than an on-roof system (roofs need ridge and eaves vents now anyway). We went down this route and it was painless and saved maybe £2k in roofing cost.

Our roof faces SW and is ~12.m x 7.8m, pretty much all of it covered in panels. Makes us pretty much grid independent a lot of the time in summer, along with a stack of 6 Pylontech US300C batteries. Over the past week or so we've not used a single unit of grid energy, and we've been charging the car for free pretty much since the end of Spring.

[Stinsy]

Hi Brave Knights of the Round Table
My friend is doing a self-build, and is getting to the part where he's looking to spec and install some renewable generation.
The south-facing aspect of his roof is essentially unlimited size - 9m x4m!
He also has a 3-phase electricity supply (the plot was ex-light industrial)

I have offered to help him get the right kit.
He'll also have an Air Source Heat Pump which he plans to use for space heating and hot water.
He has an EV, so will want a car charger, and he's also keen on getting a stationary battery for the house too. He wants to be as grid-light as possible.

Given it's a self-build, and there's no FiTs anymore, I guess he can do a DIY installation and not be too concerned?

Was thinking 9kW or 12kW of solar - so 3 or 4kWp on each phase?
With that size roof I guess go for the lowest cost £/W panels rather than gunning for Ultra high power ones?
Any good 3-phase SolarPV inverters out there?
Thinking a "Hybrid" inverter that could also control a battery system
A Zappi for the EV
And a PylonTech battery system ?

Do I actually suggest to him doing a split array rather than sticking it all on South?

That is all good advice. If he’s building then “in-roof” is a no-brainer.

Solax do a modestly priced 3-phase hybrid inverter: https://www.solaxpower.com/wp-content/u ... brid-1.pdf

[ALAN/ALAN D]

Reference. Three Phase Supply.

How much load has he got on each phase.
Some older houses get fed with two / three phases and use one phase as an economy 7 supply.
Best to find out what his house load / hot water tank / electric house heating system is going to be. ?

[nowty]

If I had a self build with 3 phase from scratch, my wish list would be,

5 or 6 kW solar PV per phase, 16 x US5000 (77kWh Pylontech stack), 3.68kW battery inverter per phase (running off single battery stack), 2 x A2A heatpumps (one upstairs and one downstairs), 2 x car chargers, solar diverter's to hotwater, 1000 litre heatstore, ASHP + underfloor heating and about 10kW of a ripple windfarm.

Depending on the size of the new build you can probably pro rata reduce down the wishlist.

[spread-tee]

I would also seriously consider an interseasonal underground heatstore assuming there is room and a digger will be onsite for the ground works.

Desp

[Countrypaul]

9m x 4m is not that large a roof. You are looking at less than 18 panels, even at 500Wpeach that would still be only 3KW per phase (and the 50Wp panels are larger than 1m x 2m). If you have to look at a margin round the panels the space available reduces significantly and so does the panel output.

Is 9 x 4 for each side of a pitched roof - if so then I suspect you may want to consider a split sysem and higher power panels.

I agree about in-roof, we did so when renovating and it is much neater and saved significantly on tiling.

Consider an Eddi as well as a Zappi.