PV on an outbuilding belonging to another property

[cojmh]

This is perhaps a bit of an odd query but one I am hoping to find the solution to as I am bringing forward some RE plans given the on going energy crisis.

Basically we are in the fortunate position to own the house next door to our own and we rent out this second house.

The second house has an outbuilding (a large garage) that we have separated off from the rental house for use by me as a workshop.

I am hoping to put 5KW of PV on the roof of the garage and connect it to my house but I am mindful if I ever need to sell the second house then that would mean selling the outbuilding and changing the solar setup.

Currently the outbuilding can be supplied by my house or the rental house (They are not connected together - there is a feed available from both houses and an electrician just needs change the tails in the consumer unit to one or other of the supplies).

My current thought is:

• Apply to the DNO for permission for this system as if it is part of my house (I already have permission for 5KW on my house). I would probably ask for 8KW extra.

• Install a the inverter and a battery stack in the outbuilding

• Run an ethernet cable from my house to the garage so that I can put a CT clamp on my supply for the inverter in the outbuilding

As far as I am aware this is all legal and should be easy enough to do?

If I was ever to sell the house (or both houses) then I would just decommission the outbuilding solar (and probably leave it to the purchaser to sort out how they want to deal with it - or I could apply for DNO for the second house and get connection changed over (the main issue would be CT clamp to the rental house).

I am after feedback to see what you all think about the proposed plan and whether or not you can see any pitfalls or things I should be doing differently?

Thanks,

[Stinsy]

I don’t see any problem. You own it you can do what you like!

The DNO might have a problem with that much inverter capacity (assuming single-phase), but there are solutions to that…

[nowty]

Only thing I would recommend is keeping the next door outbuilding inverter size to 3.68kW, that way if you sold next door, it could simply and legally be re-connected to next doors supply under G98 post install notification rules. You probably would not get away with anything larger anyway.

Something like a SOLIS RHI-3.6K-48ES-5G 3.6KW HYBRID SOLAR INVERTER can still take up to 7kW of panels.

[AE-NMidlands]

you could write a "contract" with yourself to give your house ongoing right of access and use of the roof and attach it to the deeds of the next-door house at the Land Registry.

Nowty's idea is probably better as it would enhance the sale value - rather than knock it down which my idea probably would.

[cojmh]

Thanks for all the answers.

I suspect there is a bit of nuance here:

Only thing I would recommend is keeping the next door outbuilding inverter size to 3.68kW, that way if you sold next door, it could simply and legally be re-connected to next doors supply under G98 post install notification rules. You probably would not get away with anything larger anyway.

Something like a SOLIS RHI-3.6K-48ES-5G 3.6KW HYBRID SOLAR INVERTER can still take up to 7kW of panels.

In a situation with 5KW of panels would this inverter still be able to use the 5KW of solar power even given it's 3.6KW inverter? I am just a little confused about the amount of panels it can take versus the rating of the inverter. Sorry if that is a thick questions.

Thanks,

[Stinsy]

Thanks for all the answers.

I suspect there is a bit of nuance here:

Only thing I would recommend is keeping the next door outbuilding inverter size to 3.68kW, that way if you sold next door, it could simply and legally be re-connected to next doors supply under G98 post install notification rules. You probably would not get away with anything larger anyway.

Something like a SOLIS RHI-3.6K-48ES-5G 3.6KW HYBRID SOLAR INVERTER can still take up to 7kW of panels.

In a situation with 5KW of panels would this inverter still be able to use the 5KW of solar power even given it's 3.6KW inverter? I am just a little confused about the amount of panels it can take versus the rating of the inverter. Sorry if that is a thick questions.

Thanks,

3.6kW is a perfectly acceptable inverter size for 5kWp of panels!

Firstly your panels rarely generate their rated power, and even then only for short periods. In blazing august sunshine the panels jut get too hot and in winter the sun isn't strong enough even when it does shine.

Next a hybrid inverter will divert excess onto the batteries. So if your panel are producing 4.6kW while your BEV is charging, or your electric shower is being used, 3.6kW will go towards the demand and 1kW will go into the batteries.

[cojmh]

3.6kW is a perfectly acceptable inverter size for 5kWp of panels!

Firstly your panels rarely generate their rated power, and even then only for short periods. In blazing august sunshine the panels jut get too hot and in winter the sun isn't strong enough even when it does shine.

Next a hybrid inverter will divert excess onto the batteries. So if your panel are producing 4.6kW while your BEV is charging, or your electric shower is being used, 3.6kW will go towards the demand and 1kW will go into the batteries.

Thank you for the explaination.

I was not totally clear in my initial post as I do have the scope to add further panels (possibly an additional 7kw on top of the 5KW that I was looking to add to the garage roof). So the 8KW I was asking for from the DNO could potentially have 12KW of panels connected. I was limiting the ask to 8KW as I expected the DNO to come back with somewhere between 5KW and 8KW of additional capacity based on the 5KW I already have permission for.

Sorry that was not stated initially as I thought the issue would be with setups on different properties (as opposed to the size of the setup).

I guess the best thing to do is have a chat with the DNO to see what they would be happy with (if this is something that the DNO will do?).

From reading other threads my understanding was that it would be possible to have a larger hybrid inverter and limit it's export capacity to keep the DNO happy (or am I missing something).

I appreciate that you are trying to save me money by getting appropriately sized equipment so thank you for that.

Cheers,

[nowty]

cojmh, please be a bit more clear of what you mean by kW capacity of what you have and what your DNO approved for.

There is the kWp of the panels, there is the kWp (uncapped) of the inverter(s) and there is the kWp of max export.

Its generally the uncapped kWp of the inverter(s) the DNO is primarily concerned about, but that can be mitigated with export limitation in some circumstances.

Generally the DNO is not interested in the kWp of the panels. I used to say its non of the DNOs business but an over the top PV array may interfere with the operation of some export limitation systems meeting the G100 specs if your going down the G99 route.

[cojmh]

cojmh, please be a bit more clear of what you mean by kW capacity of what you have and what your DNO approved for.

Thanks for the response.

What I currently have:

I have a letter from Western Power that says I can export up to 5KW which is the same as the maximum capacity of the current inverter I have (and 4.7KW of panels on the roof).

What I intend to install Phase 1:

In terms of what I want to install - I was intending to add 5KW of panels on the garage initially and if this is enough for our usage etc. then stick with that.

What I intend to install Phase 2 (if necessary):

If I think that our usage can still benefit from more panels then I have the option of hooking in 2kw of panels from the motor home (which is a future upgrade to the motorhome) whilst it is parked on the drive and possibly another 5kw of panels on a car port. However if we don't need it then I won't.

In terms of phase 1 and phase 2 - I have nothing yet, just in the initial ideas and figuring out how to do it with minimal fuss. I am looking to get permission from the DNO for what I think could be the maximum that I need for phased 1 and 2 as opposed to changing things in the future - or the maximum they will give me if that is less than what I ask for.

In terms of limiting export etc. if this is required by the DNO then this is something that I can do, my primary focus is getting our reliance on grid power and FF power down to a minimum. However if I have excess then I would hope it can be used to reduce the carbon foot print of someone else (i.e. exported). But if this is not possible then so be it.

So my initial thought was to go with an 8KW rated hybrid inverter with 5KW of panels, with the scope to go up to 12KW of panels.

But I acknowledge that I have very little experience in this field so thought I would ask for opinions and thoughts.

Thanks

Jonathan

[cojmh]

Sorry, I should say that I am expecting our summer usage to still exceed an additional 5KW - hence the phase 2 extension.