Hello - PV newbie seeking some advice

[user 37834]

Hi everyone.

I am about to embark on a loft extension and have a company lined up to begin next week.

I don’t have the money for PV panels this year but would definitely like to future proof the build so that the wiring (and anything else that’s required) is ready for when I do decide to go for it.

I’d be really grateful to know what I need to do so that any future installer doesn’t have to retrofit anything – and so damage the nice finished walls!

Thanks in advance,
Dave

 

[Geoff1946]

Think where you may want anything at all and run in plastic conduits to accessible points.
Costs little and so doesn't matter if you don't use it.
Solar will need a convenient place to come into the building an isolator switch and a cable route to wherever you would locate the invertor and anything else related that you envisage, such as batteries.

 

[binky]

Main thing us a suitable location for the inverter and/ or batteries. They need quite a large space to dissipate heat, and batteries don't like the cold, or getting over hot. Once you've worked that out, it's easy enough to work out cable runs.

 

[user 37834]

Think where you may want anything at all and run in plastic conduits to accessible points.
Costs little and so doesn't matter if you don't use it.
Solar will need a convenient place to come into the building an isolator switch and a cable route to wherever you would locate the invertor and anything else related that you envisage, such as batteries.

Hello, in that case I will run conduits to each end of the roof just to be sure.
I had a quick look at conduit supplies - do you think 20-25mm would be sufficient?
Thanks again for your help.

 

[user 37834]

Main thing us a suitable location for the inverter and/ or batteries. They need quite a large space to dissipate heat, and batteries don't like the cold, or getting over hot. Once you've worked that out, it's easy enough to work out cable runs.

Hello, I hope I will have plenty of space for that. The solar panels would be mounted on the same side as the eaves storage that will be created. It will be insulated to building regulations, so there certainly won't be an issue with cold. Thanks very much for your advice.

 

[Geoff1946]

do you think 20-25mm would be sufficient?

20mm conduit meets most domestic installation needs.
If you want 'phone, network, TV aerial or video these need their own conduit and shouldn't share with mains.

 

[binky]

Hello, I hope I will have plenty of space for that. The solar panels would be mounted on the same side as the eaves storage that will be created. It will be insulated to building regulations, so there certainly won't be an issue with cold. Thanks very much for your advice.

eaves can be rather warm, but main thing is air movement. Inverters use natural convection cooling, so must have air movement or space for that to happen. They do also have overheating protection, but it can be rather irritating on a bright, sunny, summers days to find the inverter has got too hot and partially shut itself down. I've always preferred to mount soalr inverters outdoors on a shady wall, batteries are a different kettle of fish, they really don't like getting cold, and aren't suitable for outdoor mounting anyway. Some members on here have put batteries in small wooden sheds with heating mats for the coldest weather to stop them getting too cold mid winter. I would send some time reading up on it, and come back with any queries.

As for conduit, run 25mm as you can get 4 dc cables down that if needed - 20mm tends to be too tight. If you add batteries, then you will need separate conduit for any comms cables. easiest option is run 3 lots of conduit to ensure no problems.

One other thing you might contemplate is in-roof solar mounting such as GSE. It costs more than on-roof, but much of that cost is offset by savings on the roof covering itself.

 

[user 37834]

eaves can be rather warm, but main thing is air movement. Inverters use natural convection cooling, so must have air movement or space for that to happen. They do also have overheating protection, but it can be rather irritating on a bright, sunny, summers days to find the inverter has got too hot and partially shut itself down. I've always preferred to mount soalr inverters outdoors on a shady wall, batteries are a different kettle of fish, they really don't like getting cold, and aren't suitable for outdoor mounting anyway. Some members on here have put batteries in small wooden sheds with heating mats for the coldest weather to stop them getting too cold mid winter. I would send some time reading up on it, and come back with any queries.

As for conduit, run 25mm as you can get 4 dc cables down that if needed - 20mm tends to be too tight. If you add batteries, then you will need separate conduit for any comms cables. easiest option is run 3 lots of conduit to ensure no problems.

One other thing you might contemplate is in-roof solar mounting such as GSE. It costs more than on-roof, but much of that cost is offset by savings on the roof covering itself.

We will be building a properly insulated, windowless utility room on the ground floor - so based on what you have said, I think it would be sensible for me to integrate coupling to reach this room for inverter/battery storage.

Sorry to hammer the point, but do you recommend 3 conduits for solar alone - so I should add another 25mm conduit for aerial and broadband cabling (just to be sure)?

Yes, I went to a trade show and saw GSE and thought that would be a good option. My tiles will probably need replacing soon, so it makes sense. It looks slicker too, I reckon.

Thanks again for your help.

 

[binky]

We will be building a properly insulated, windowless utility room on the ground floor - so based on what you have said, I think it would be sensible for me to integrate coupling to reach this room for inverter/battery storage.

Sorry to hammer the point, but do you recommend 3 conduits for solar alone - so I should add another 25mm conduit for aerial and broadband cabling (just to be sure)?

Yes, I went to a trade show and saw GSE and thought that would be a good option. My tiles will probably need replacing soon, so it makes sense. It looks slicker too, I reckon.

Thanks again for your help.

Utility room is perfect - fitting heavy inveters and batteries in under eaves spaces can be back breaking work. So based on downstairs area, 25mm conduit to roof for the DC cabling should be fine (NB try to avoid bends), based on 2 string array. Separate conduit for aerial and boroadband, as we dont like to mix power with signal cabling. Run say 6mm for AC to utility room, and you may need a cat 5 cable for amp clamp if you fit batteries - depends on how hard it is to get to main consumer unit on your house. I'm saying 6mm as that will give you upto 40Amp or 9kW supply, and even if you only fit say a 4kW system, it helps keep cable cool and is simply more efficient for little extra cost over say a 2.5 or 4mm cable. Larger cable will also allow for possible cable derating due to insulation - run a cable through 500mm of insulation and we derate it by half.

One other thing to consider, battery and no solar is quite popular these days. This allows you to take advantage of off peak leccy tariffs without the cost of accessing roof to fit panels. It's a shame you havn't the budget to do the solar as part of the build as you would already have the scoffolding up, and you could fit an in-roof solar system, which looks a lot better than on roof, and doesn't involve invalidating any roofers warranties fitting an on-roof system. It costs more in materials, but that additional cost is offset in savings on slates or tiles for the roof