Installing panels on a garden room.

Ruislip Resident · Dec 28, 2024

My house ( mid terrace) roof has a dormer on one side (probably too weak for the ballast to hold down solar panels and difficult I think to assess so too much risk.of collapse) and three velux windows and a wrongly shaped / positioned gable on the other side. So the main roof is not really suitable for panels. Also with the loft converted I don't really have space for all the inverters, battery storage etc. The rear of the house has a kitchen extension which at best gets sunlight till about 2pm on side of it in the middle of summer, so again not that suitable. However I have a garage at the end of the garden ( rear access road ) which is never in the shade, even with a big tree in a garden nearby on the other side of the access road. It's not in good enough nick to fit panels, battery storage. However at some point ( probably within the next few years ) I'd like to get it replaced with a large garden room, either under permitted development or proper planning permission. It would then be a suitable position to have solar panels, battery storage and possibly a heat pump. I dont mind digging channels in the current garden for cables etc as its not that fancy so nothing expensive would be getting ruined. Has anybody ever had such a project done. Although I have looked extensively on Google, You Tube etc , I've never found a company / developer in a case study showing them doing both the build and the solar / battery and possibly heat pump installation. They are always one or the other.

Brian0 · Dec 28, 2024

I'm not sure of the details, but I know the rules are different for installation on a separate property. Check with your local council. Usually they are quite relaxed about interpretation of the rules.

PVperson · Dec 28, 2024

Ruislip Resident said:
My house ( mid terrace) roof has a dormer on one side (probably too weak for the ballast to hold down solar panels and difficult I think to assess so too much risk.of collapse) and three velux windows and a wrongly shaped / positioned gable on the other side. So the main roof is not really suitable for panels. Also with the loft converted I don't really have space for all the inverters, battery storage etc. The rear of the house has a kitchen extension which at best gets sunlight till about 2pm on side of it in the middle of summer, so again not that suitable. However I have a garage at the end of the garden ( rear access road ) which is never in the shade, even with a big tree in a garden nearby on the other side of the access road. It's not in good enough nick to fit panels, battery storage. However at some point ( probably within the next few years ) I'd like to get it replaced with a large garden room, either under permitted development or proper planning permission. It would then be a suitable position to have solar panels, battery storage and possibly a heat pump. I dont mind digging channels in the current garden for cables etc as its not that fancy so nothing expensive would be getting ruined. Has anybody ever had such a project done. Although I have looked extensively on Google, You Tube etc , I've never found a company / developer in a case study showing them doing both the build and the solar / battery and possibly heat pump installation. They are always one or the other.

As you may guess from my username here, I'm an expert in PV and renewable, I have over 8kW on outbuildings, (saving the house roof for solar-thermal!) I would always use a reputable installer, and have PV (panels) bolted down to the roof structure, high winds are becoming more and more common in London, and the force will easily exceed the weight of the PV, even with "ballast"
Your best way to save power in winter is put a min of 15cm of PUR/PIR insulation on the external walls. your heating bills will drop so much you'll be able to afford the charge the EV without solar PV!

johnb80 · Dec 28, 2024

Consider battery only install and get your peak use to off peak rate eg (5p kWh)

Grandadgeorgec · Dec 28, 2024

johnb80 said:
Consider battery only install and get your peak use to off peak rate eg (5p kWh)

I have a small 2 bed bungalow and the roof area/configuration rules out solar. However, I am awaiting a battery only install in January to take advantage of the cheap rate as you said in your post.

johnb80 · Dec 28, 2024

Grandadgeorgec said:
I have a small 2 bed bungalow and the roof area/configuration rules out solar. However, I am awaiting a battery only install in January to take advantage of the cheap rate as you said in your post.

Good choice, you can then get usage like this:-

This is typical of how my system runs, some nights we have much higher consumption if we charge both cars and run the washing machine and tumble drier.

Gomev · Dec 29, 2024

Ruislip Resident said:
My house ( mid terrace) roof has a dormer on one side (probably too weak for the ballast to hold down solar panels and difficult I think to assess so too much risk.of collapse) and three velux windows and a wrongly shaped / positioned gable on the other side. So the main roof is not really suitable for panels. Also with the loft converted I don't really have space for all the inverters, battery storage etc. The rear of the house has a kitchen extension which at best gets sunlight till about 2pm on side of it in the middle of summer, so again not that suitable. However I have a garage at the end of the garden ( rear access road ) which is never in the shade, even with a big tree in a garden nearby on the other side of the access road. It's not in good enough nick to fit panels, battery storage. However at some point ( probably within the next few years ) I'd like to get it replaced with a large garden room, either under permitted development or proper planning permission. It would then be a suitable position to have solar panels, battery storage and possibly a heat pump. I dont mind digging channels in the current garden for cables etc as its not that fancy so nothing expensive would be getting ruined. Has anybody ever had such a project done. Although I have looked extensively on Google, You Tube etc , I've never found a company / developer in a case study showing them doing both the build and the solar / battery and possibly heat pump installation. They are always one or the other.

Have a look at this thread where it has been done. A member @Hotlush did more or less exactly what you want. Hotlush does post throughout the thread with details from start to finish.

Solar PV - no roof space

So we've had some quotes and they've basically knocked the idea of having solar PV on the house roof on the head due to the dormer. We had already been planning to get a summer house at the bottom of the garden so thinking of accelerating that and use it's roof space. We're lucky enough have a...

www.mgevs.com

Radders · Jan 4, 2025

We have a South facing flat roofed garage approx 10mtr x 4mtr. In Yorkshire Anyone able to give a laymans opinion on best way forward. We also have an EV

Richard P · Jan 4, 2025

We've a similar property. I installed batteries and inverter under the stairs and charge up overnight. Works well BUT I now realise it would have been far more cost effective to just use the capacity of the car battery - in fact would have been cheaper to upgrade to a LR vehicle as 7kWh of batteries plus inverter etc were around £6K

johnb80 · Jan 4, 2025

Richard P said:
We've a similar property. I installed batteries and inverter under the stairs and charge up overnight. Works well BUT I now realise it would have been far more cost effective to just use the capacity of the car battery - in fact would have been cheaper to upgrade to a LR vehicle as 7KWh of batteries plus inverter etc were around £6K

Not if you buy wisely it isnt.

Fogstar
14 kWh battery £1500

Inverter
Victron Multiplus II 5000 W £850 from Amazon and other places.

Bam Bam · Jan 4, 2025

Radders said:
We have a South facing flat roofed garage approx 10mtr x 4mtr. In Yorkshire Anyone able to give a laymans opinion on best way forward. We also have an EV

If it is isn't heavily shaded and can take the weight then maybe you can get some rows up there.

Get a few local MCS installers to go round and have a look and see what they suggest.

Solar + Battery is a great set-up.

Home batteries go great with solar and EV because you charge them up with the cheap overnight EV tariff and use that cheap electricity during the day.

damo2929 · Jan 5, 2025

Richard P said:
We've a similar property. I installed batteries and inverter under the stairs and charge up overnight. Works well BUT I now realise it would have been far more cost effective to just use the capacity of the car battery - in fact would have been cheaper to upgrade to a LR vehicle as 7kWh of batteries plus inverter etc were around £6K

BS 7671:2018+A3:2024 states it's now against regulations to have a battery and inverter under the stairs or in the path of a fire escape. They recommend being outside or in an outbuilding.

Having it under the stairs will make your home insurance invalid.

johnb80 · Jan 5, 2025

damo2929 said:
BS 7671:2018+A3:2024 states it's now against regulations to have a battery and inverter under the stairs or in the path of a fire escape. They recommend being outside or in an outbuilding.

Regulations aren't applied retrospectively, my professionally MCS installed, Growatt battery and Inverter is in the loft.

damo2929 said:
Having it under the stairs will make your home insurance invalid.

Dependent on when it was installed and I think may make your insurance invalid rather than will make your insurance invalid is more accurate. I informed my insurers about my solar inverter and battery being in the loft and they didnt have a problem with it at all.

EV convert · Jan 6, 2025

Never mind installing indoors, Under PAS 63100:2024 even positioning batteries outdoors is banned within 1m of a door or window - even if there are two or more exits! So if you have a terrace house then forget about installing a battery.

I did ask BSI why that was but didn't get a meaningful reply and when I persisted the replies dried up all together.

Everest · Jan 6, 2025

damo2929 said:
BS 7671:2018+A3:2024 states it's now against regulations to have a battery and inverter under the stairs or in the path of a fire escape.

Are you sure you're not confusing Amendment 3 with PAS 63100:2024 ? I thought that Amendment 3 only related to bi-directional protection devices

EV convert said:
Never mind installing indoors, Under PAS 63100:2024 even positioning batteries outdoors is banned within 1m of a door or window

Not strictly true - BSI - PAS 63100:2024” is advisory only. Furthermore, whilst it contains a number of sensible and logical safety recommendations, there are also a large number of gaps in this first edition of the Publicly Available Specification. For example battery chemistry is overlooked, as are battery voltages wrt. DC arc risks. Even Tesla have questioned some of the "recommendations" that they are non-compliant with in their Powerwall product.

Richard P said:
BUT I now realise it would have been far more cost effective to just use the capacity of the car battery

Doing that is unlikely to be cost effective due to the inefficiencies of the AC-coupled V2L connection - see my posting here regarding that issue.

V2G to be approved in Australia 2025

Not sure I'd agree with that Oh! That’s that idea blown out of the water 😂. I’m sure there must be work arounds but the 70% efficiency may be an issue. I estimate my home battery loose about 10% in battery to AC. If the capabilities were built into wall box. But not implemented until usable is...

www.mgevs.com

johnb80 · Jan 6, 2025

Everest said:
Doing that is unlikely to be cost effective due to the inefficiencies of the AC-coupled V2L connection - see my posting here regarding that issue.

Even with very low efficiency (I doubt it is as bad as you stated) it's still very cost effective to replace Energy costing 23.2p per kWh with energy plus losses that cost 5p per kWh!

Everest · Jan 6, 2025

johnb80 said:
Even with very low efficiency (I doubt it is as bad as you stated) it's still very cost effective to replace Energy costing 23.2p kWh with energy plus losses that cost 5p kWh!

At those prices, I agree.

EV convert · Jan 7, 2025

Everest - thanks for your comment and you are quite correct in saying PAS 63100:2024 "is advisory only".

However, home owners have to consider the potential consequences of not following the guidelines - would house insurance become invalid in the case of a fire (not even one involving the battery)? Would you be able to rent out or even sell a house with a non-compliant battery installation (look at the problems 'rent a roof' solar installations have created)?

And would registered installers even fit batteries in non-compliant locations as their registration status could potentially be compromised?

Alternatively, if you have to build an enclosure or fit a fire rated window and/or door, the cost will increase dramatically and it becomes a financial non-starter.

For all those reasons I believe PAS 63100:2024 does ban a large proportion of the housing stock from having battery storage installed.

T1 Terry · Jan 7, 2025

Ruislip Resident said:
My house ( mid terrace) roof has a dormer on one side (probably too weak for the ballast to hold down solar panels and difficult I think to assess so too much risk.of collapse) and three velux windows and a wrongly shaped / positioned gable on the other side. So the main roof is not really suitable for panels. Also with the loft converted I don't really have space for all the inverters, battery storage etc. The rear of the house has a kitchen extension which at best gets sunlight till about 2pm on side of it in the middle of summer, so again not that suitable. However I have a garage at the end of the garden ( rear access road ) which is never in the shade, even with a big tree in a garden nearby on the other side of the access road. It's not in good enough nick to fit panels, battery storage. However at some point ( probably within the next few years ) I'd like to get it replaced with a large garden room, either under permitted development or proper planning permission. It would then be a suitable position to have solar panels, battery storage and possibly a heat pump. I dont mind digging channels in the current garden for cables etc as its not that fancy so nothing expensive would be getting ruined. Has anybody ever had such a project done. Although I have looked extensively on Google, You Tube etc , I've never found a company / developer in a case study showing them doing both the build and the solar / battery and possibly heat pump installation. They are always one or the other.

Have you though about getting a stand along solar array built with a large single wall facing the optimum angle to get the best solar harvest. Have it set up as off grid as an EV charging facility ......... If you have it built in such a way that it could act as a shelter for the EV, even better.

Once it is all passed and certified fill in part of the walls to grow your garden under it if that is what you really want. As long as the solar array is certified along with the inverter and battery, and it is not attached to the house itself, that should be a loophole to get what you want with the required permissions.

If you do have an EV, you could add to the off grid storage battery required for the solar and inverter energy storage while the vehicle is in use, claiming it will need to recharge the EV when it gets home after the good sun hrs have past.
You could charge up the battery during the day, as well as the EV, then run parts or all of the house from the inverter and battery while topping up the house battery via V2L to provide free power you harvested from the sun.....

T1 Terry

T1 Terry · Jan 7, 2025

Radders said:
We have a South facing flat roofed garage approx 10mtr x 4mtr. In Yorkshire Anyone able to give a laymans opinion on best way forward. We also have an EV

We installed a solar set up for a similar building in a South Australian town. We used solar racking that could be adjusted to the correct tilt for late spring through to early autumn, then stood up straighter for late autumn through to early spring to catch the sun when it was lower in the sky.
We had to do quite a bit of strengthening under the roof and extra legs bolted to the cement floor to not only share the weight, but to brace the roof against high winds with the panels mounted at an angle like that. That was in 2018 and it's still holding up fine, as are the batteries.

T1 Terry

Installing panels on a garden room.

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