Balcony Solar Is Coming!

[SteamyTea]

I am currently reading Howard Mark's Mr. Nice.

Seems you can buy anything, anywhere.

[Dillsue]

22 hours ago, Mattg4321 said:

yet old Joe Bloggs can nip to Wickes and he’s fine to plug it into a system that isn’t safe to start with and has now been made even worse by him pushing power through devices in the wrong direction. 

Don't forget that earth leakage detection and tripping is a secondary safety feature and if Joe bloggs is plugging into system that isn't safe it's not because he doesn't have bi directional earth leakage detection.

[Ferdinand]

Serious question on this one:

As a landlord, what do I need to worry about with electrical systems in rented dwellings wrt balcony solar?

My practice has been to rewire or professionally review the wiring, usually with a new consumer unit.

These days 5-yearly electrical inspections are required, with potentially swingeing fines (tens of thousands) just from a Council in England, just as a civil penalty before it gets to Court.

Are there extra inspections or insurance I need to consider, in case a T gets a balcony solar and just sticks it into one of my systems which has something that is not covered by the standard regimen? This is the sort of thing a tenant would just do. A few would check with the LL; most would not.

If they are a T who has had their own house previously they would be aware, but many Ts do not know how to run a house. Around here it is mainly unfurnished, so most have at least some idea of looking after a house.

What are the failure modes - will I have an RCBO going pop or a house burnt down?

Comments welcome.

[Mattg4321]

1 hour ago, Dillsue said:

Don't forget that earth leakage detection and tripping is a secondary safety feature and if Joe bloggs is plugging into system that isn't safe it's not because he doesn't have bi directional earth leakage detection.

You’re possibly correct with the second part of that. I wouldn’t be too worried at all if all else was correct other than having uni directional rather than a bi directional device fitted. 
 

RCD protection is sometimes “additional protection” and sometimes “fault protection”. Most usually in the case of fault protection in TT systems where they are often the only method of protection as fault currents are too low for fuses/MCB’s to operate in a line to earth fault scenario. 

[Mattg4321]

1 hour ago, Ferdinand said:

Serious question on this one:

As a landlord, what do I need to worry about with electrical systems in rented dwellings wrt balcony solar?

My practice has been to rewire or professionally review the wiring, usually with a new consumer unit.

These days 5-yearly electrical inspections are required, with potentially swingeing fines (tens of thousands) just from a Council in England, just as a civil penalty before it gets to Court.

Are there extra inspections or insurance I need to consider, in case a T gets a balcony solar and just sticks it into one of my systems which has something that is not covered by the standard regimen? This is the sort of thing a tenant would just do. A few would check with the LL; most would not.

If they are a T who has had their own house previously they would be aware, but many Ts do not know how to run a house. Around here it is mainly unfurnished, so most have at least some idea of looking after a house.

What are the failure modes - will I have an RCBO going pop or a house burnt down?

Comments welcome.

As they are effectively portable appliances, then I can’t see how you can possibly be held liable for any injury that occurs due to equipment that you are not aware of and has been installed by the tenant. Same as with any faulty appliance owned by the tenant. You could insist they test all their appliances I suppose. 
 

The other risk would be a fire risk and what effect this would have on your buildings insurance - would they cover a fire caused by faulty balcony solar?
 

The rules brought in a few years ago mandating electrical inspections have actually worked quite well and the average rental is probably in slightly better condition than the average owner occupied house these days - from an electrical point of view. 
 

The biggest risk other than pre existing electrical installation faults is probably the imbecile that installs it so it takes off and kills someone at the first sign of windy conditions or catches fire where they’ve shut the lead in the window/door etc. I’m sure we’ll also see people cutting the plugs off and badly reinstalling them and people plugging in multiple systems into the same circuit. 
 

On that last point, if you have say 3x (or more) 800w systems on a standard 20 amp radial circuit that might already be running at capacity as it’s feeding a tumble dryer and hot tub outside, then you’re moving into fire risk territory. 
 

You have a circuit that is designed for max 20 amps that could now be taking more like 30 amps. 

[Ferdinand]

Thanks @Mattg4321.

The angle I am coming from is risk management - a huge part of effective landlording is understanding the locus of potential tenant behaviours and lifestyle, and having a robust property that manages the risky ones out before they start.

The reason is that once it gets into the consequences the implications become horrific because a Council will go in feet first and HARD, and a single problem can destroy an entire business - or in my case future pension provision. The blame will *always* be on the LL not the T.

Equally something like a gas problem born from simple neglect can have consequences up to and including death, and constant sweating of the detail is the only strategy. My risk management for that as soon as I can will be all electric houses.

And risks can only be managed in advance - which is why credit checks etc need to be obsessive.

Three examples of strategies I pursue routinely are to install enough sockets so that extension leads will *never* be needed - in the last 8x8ft kitchen I renovated there were about 11 double sockets plus appliance ones below the worktops. And provide constant trickle ventilation (poor man's MVHR - loft PIV fan and a trickle HR ventilator downstairs) to maintain a fresh atmosphere just in case eg washing is dried inside, and install shelves immediately above every radiator so washing physically cannot be added.

So I'm just thinking through balcony solar.

I suspect one I need to look at is the type of RCBOs.

Cheers

F

[SteamyTea]

1 hour ago, Ferdinand said:

The angle I am coming from is risk management

Can you specify that they must not use one.

As pointed out above, it is not just the wiring load, there is also the problems with the kit cluttering up the place and possibly falling.

It is not unusual to make minor changes to contracts.

[Ferdinand]

29 minutes ago, SteamyTea said:

Can you specify that they must not use one.

As pointed out above, it is not just the wiring load, there is also the problems with the kit cluttering up the place and possibly falling.

It is not unusual to make minor changes to contracts.

Yes - they could be excluded in the same way as "no washing on the balcony" in the contract.

But I can't see that sticking for ever, once they are in safe use.

[Mike]

On 23/05/2026 at 17:14, Ferdinand said:

Yes - they could be excluded in the same way as "no washing on the balcony" in the contract.

However such restrictions could be voided by the law, as has happened in Germany.

 

I'd sit on my hands for now and see what happens.

[DamonHD]

FWIW, I established with my FiT administrator that it should be OK to add balcony solar to an existing house that has deemed exports:

 

https://www.earth.org.uk/note-on-GB-FiT-and-plug-in-solar.html

[Beelbeebub]

On 23/05/2026 at 13:55, Mattg4321 said:

On that last point, if you have say 3x (or more) 800w systems on a standard 20 amp radial circuit that might already be running at capacity as it’s feeding a tumble dryer and hot tub outside, then you’re moving into fire risk territory. 
 

You have a circuit that is designed for max 20 amps that could now be taking more like 30 amps. 

I see this point come up alot, but wouldn't it only apply if the person overloaded the circuit to begin with? 

 

If you have a standard ring on a 32a breaker they can run several appliances together, say 3, up to the 32a limit, but the typical 2.5mm cables are only rated for 20a and the whole concept relies on both ends of the ring taking the load so no one part ever sees more than 20a.

 

A person could run more than 32a of load if the additional current was provided by the solar but as long as the wiring run from the solar to the load wasn't exceeding 20a it would be fine. 

 

So a tumble dryer plugged into the same double socket as the solar would be fine. 

 

The problem might occur if the loads and sources were too far apart or unbalanced but that is a statistical risk the ring main system accepts anyway. 

[JohnMo]

On 29/03/2026 at 10:49, ProDave said:

That's more for an 850W system than it cost me for my original 3.68kW system.

 

No wonder there is interest in selling this plug and play kit, it allows suppliers to charge a lot for a small system just for the users that think they are getting something special.

Completely agree. Many on are talking about what if.. lots of multiple systems on one circuit etc.

 

Who in the right mind would bother. You are royally ripped off on one system, so why would you buy multiple systems. Plus if your in a flat (the reason these systems exist) where do you put all these panels for multiple systems, most would struggle with a couple of large format panels.

[Beelbeebub]

I think the plug in battery systems might end up being the better solution.  A 1 or 2kwh plug in unit - especially if linked to time of use tariffs - could make a big difference to bills and the current 4-pm demand peak.

 

I keep thinking that octopus or similar could offer a tariff where you get a plug in battery and got a guarenteed low price for Xkwh a day.  Say you pay £1 a day all in for 5kwh with the rest charged at normal rates - maybe a roll over/forward facility up to 10kwh in a single day. The energy supplier would make their profit by charging the battery at cheap periods and thus reducing their volume a at high price periods. 

 

If such device were just a suitcase sized box delivered to your door, connected to WiFi and plugged in somewhere it could get really good uptake. 

[SteamyTea]

16 minutes ago, Beelbeebub said:

think the plug in battery systems might end up being the better solution

Posted up a bit about small (around 1 kWh) systems a few years ago.

The economics still say it is cheaper for the DNO to do it at the substation level.

[Beelbeebub]

8 hours ago, SteamyTea said:

Posted up a bit about small (around 1 kWh) systems a few years ago.

The economics still say it is cheaper for the DNO to do it at the substation level.

That may be a technically and economically better solution, but it may be difficult to create the incentives for that to happen. The hardware needs to go into the substation area, which is owned and operated by thr DNO, who has no interest in the consumer or the wholesale market. The energy Co doesn't have access to that facility.

 

Putting the batteries at the consumer's end is, whilst less economic, much easier - especially if it's just shipping a box to the consumer who plugs it in and connects it to WiFi. 

[SteamyTea]

22 minutes ago, Beelbeebub said:

hardware needs to go into the substation area, which is owned and operated by thr DNO, who has no interest in the consumer or the wholesale market

It may be a cheap way to reinforce the network.

The biggest losses are the local substation and 'last mile' of cabling.

The DNOs have to supply a reliable service.

[Beelbeebub]

29 minutes ago, SteamyTea said:

The biggest losses are the local substation and 'last mile' of cabling

But batteries at the substation won't help with the last mile of transmission. Pretty much by definition they are at thr junction between the low (relative to grid voltages! 😁) 240v system and the higher transmission voltages. 

 

If DNO's wanted to reduce the peak loading on their local network and avoid having to upgrade - then that might be an incentive for them to put batteries in customer's houses. But I'm not sure shirt term peak loads are that much of an issue for DNOs because of diversity. Their problem might be the sustained medium loads that never used to exist eg heat pumps and car chargers. 

 

That said, if you have an electrically heated street or estate, it would have been the case it would be sized for a sustained storage heater load overnight from everyone. So 4 or 5kw per house overnight. 

 

If you swap that out for heatpumps your load drops to maybe half or even 1/3 continuous. Which leaves the rest availible for charging cars overnight. 

[SteamyTea]

22 minutes ago, Beelbeebub said:

But batteries at the substation won't help with the last mile of transmission

They will help immensely by stabilizing voltage. Especially important with PV and heat pumps.