Agricultural installation

[itsnewtome]

Hi
I have been  asked to quote for an installation on a grain store which is situated in the middle of a farm.
The grain store has its own 3 phase supply and the roof is large enough to get approx 37kwp system.
Next door to grain store (approx 10m away) is a workshop which has quite a heavy demand for leccy which also has its own seperate 3 phase supply.
And the other side of the grain store (approx 60m away ) is the farm house with its own 3 phase supply.
The customer wants to try and supply all 3 buildings.

So is there any reason why you could not have the following?

37 kwp on grain store supplying 3 inverters.
1 x SMA 10000TL connected to workshop
1 x SMA 10000TL connected to farm house
1 x SMA 17000 TL connected to grain store.

The workshop could house its own inverter and run DC cables (armoured) to the grain store
The grain store would have its own inverter
The farm house would have an armoured cable to the grain store with the inverter there also.

The thing that is niggling me is that that would mean bringing a second AC supply into the grain store from the house.
Also is there any reason why 3 systems cant be put on one roof if all the buildings are owned by the same person?
I cant think of any reason but this is new ground for me

What am I overlooking?

I know that the DNO would need notifying about 17kwp system and also that there is multiple installs etc.

Advice please.

[Ivan]

The DNO needs notifying for ALL grid-feed systems, regardless of size.

You need to ask their permission IN ADVANCE of connection for anything over 16A/phase. So you could install 16A/phase =11.52kW on a three phase system assuming your GT inverter will limit output to 16A/phase, and one of these for each of the 3phase supplies = 34.56. Actually, you can install more PV than this without needing to ask permission first, as long as the GT inverter is limited to the 16A/phase limit.

If you ask them nicely, you may be allowed to connect up to ~17kW/phase (can't remember - is it 70A/phase?) under G83 if they play ball. You still need to ask their permission first.

Check out the FITs rates, and how they go down for systems over 10kW, and decide whether it's worth installing 11.52kW on each supply (you'll probably decide that limiting it to 10kW is more sense).

[Ted]

As these would be multiple systems with a total of 37kWp on three phase then G83 stage 2 applies, so you would need to pre-notify the DNO and get their agreement that no reinforcement (e.g. transformer upgrade) was required. If it was then the customer would have to pay that cost.

The 3 phase supplies need to be balanced across the separate phases - easiest ensured with a 3 phase inverter.

At 37kWp whether this was registered as one or 3 systems wouldn't affect the FiT rate as you would fall into the new 10-50 kW band at 32.9p either way.

If you limited it to 3 x 10kW then the rate could be 37.8p - a 20% better return. Just exceeding a band is never going to be an economic idea. But OFGEM would have to accept these as 3 separate systems rather than one, which will be a small gamble.