Domestic solar and 3-phase

[Pretty Mouth]

A customer has just bought a property. 3 bed semi, 'normal' size, but with a fair bit of land. 60A supply.

The main house will be space heated with solid fuel, but otherwise relies on electric for cooking, water heating etc.

There will be a 2 bed static park home about 30m from the main house. This will use electric for everything - heating, cooking, shower etc.

There is also a row of old stables, which will be repurposed as 2 workshops and about 6 small storage units. These collectively aren't expected to demand much of a load. No heating, the storage units will have lighting and perhaps be used to charge power tools, and the workshops are intended for light use.

There has been talk of a possible further additional residential building on the land, perhaps a small holiday let.

All of this from the same supply. The 60A supply won't be adequate for all this, so I've suggested upgrading the supply to 3-phase - one phase for the main house, one for the static park home, and one for the workshops, units, and holiday let.

At some point in the future, my customer wants solar panels on the main house. I won't be installing this, it will be a specialist - my knowledge of solar is limited, and I have never come across it on a 3-phase installation. So my question is, how does a small array such as this work with 3-phase? Would the power generated only be available on one phase, or could it be available across all phases, so it can be used where ever it is needed?

 

[littlespark]

I’m sure you get 3 phase inverters, but the costs could be way above a single phase domestic.

When we had the caravan park, we had 200 panels on the roof, 3 x single phase inverters… one onto each phase.

I don’t even think a single 100A supply would be adequate for everything.

Park homes, like static caravans, are usually propane for heating, keeping the electric draw to less than 32A.

 

[plugsandsparks]

Smallest 3 phase solar inverter i can get is 5KW, its about £100 more than the equivalent single phase, 5KW is only about 12 panels so not a big install but still need DNO approval in advance.

 

[Pretty Mouth]

Thanks for the replies guys. While the solar isn't really my problem, I want to make sure any work I do, or suggest having done, will work well with it when the time comes.

@littlespark , yes when I initially went to see the job, heating was going to be propane at the static home, but that has since changed to electric. At that time, I had considered a single phase 100A supply for all of this, however I can't see that working now.

@plugsandsparks so not a big difference in price, that's worth knowing. The solar is only expected to be a small installation

 

[plugsandsparks]

Yes inverter for TP 5KW £500, 5KW SP is £400,
"small" installation could be less than 16A around 3.6KW to achieve a G98 application post install, so installer may go for that, but TBH that is a very small installation nowadays as the panels have improved so much over the years.