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I am hoping some extra panels will be installed next Wednesday.

The simplest wiring route is along and down the outside of the house, which abuts an A road with no verge or footway. I am concerned that overhanging loads e.g. straw bales on passing lorries might damage the cables which could then injure pedestrians, of which there are quite a few.

There will probably be 4 x 4mm^2 solar cable, or possibly 1 x 6mm^2 T&E, to get less than 3% voltage drop. So what mechanical protection should I insist on?

• nothing/whatever the installers think fit

• flexible conduit like this https://www.tlc-direct.co.uk/Products/AF20BSB.html

• capping like this https://www.tlc-direct.co.uk/Products/CG192BK.html

• something else entirely?

TIA

You could fit galvanised conduit which should protect against any accidental damage or prevent any tampering.

I'd be inclined to use galvanised conduit for something that might get bashed, as the PVC stuff can get brittle when cold. Very tough and not hard to install. Only real downside is the need to cut a thread on the end of any cut length. It usually comes in 3m lengths with pre-cut threads and a coupler usually, but if a length is shortened a new thread needs to be cut on the end. The tool for doing this is about £40 IIRC. All the usual places, like Toolstation etc sell the stuff: https://www.toolstation.com/deta-galvan ... uit/p67774

There is now a non-threaded galvanised conduit system available, Conlok, the fittings are a bit more expensive but they just clamp to the conduit with set screws, avoiding the need to cut threads.

This is what the Conlok stuff looks like: https://www.cmwltd.co.uk/Metpro/Conlok- ... ed-conduit

Thanks. I have been trying to discuss this with the installers but their electrical supervisor has not got back to me in over a week which does not augur well. So have just returned from TLC with a variety of stuff as a precaution in case they don't bring anything. The capping is much more substantial than I was expecting, and if not needed TLC are very good about returns.

I hadn't considered metal conduit TBH, perhaps because there is another cable run (rainwater system controls FYI!) in flexible which has survived >10 years. But that is 12V so no hazard if exposed, 4 panels in series only ~150V but even so a nasty belt if you are unlucky.

Takes me back to when I installed a lot of trad conduit while we were re-wiring the school theatre over 50 yrs ago. Engineering Dept had proper pipe cutters, benders, threading dies, the lot so an excellent apprenticeship. No HSWA then, schoolboys working on mains panels, working at height, working with power tools, you name it.

Previous stage switchboard had a plugboard arrangement for the dimmers where you could have live plugs lying around your feet if you didn't know what you were doing. This perhaps explains why I am not keen on generator/mains/inverter changeover switching which relies for safety on operating switches in a particular order.

Use SWA cabling easier then metal conduit

AGT wrote: ↑Sat Nov 26, 2022 3:25 pm Use SWA cabling easier then metal conduit

True, but that then needs two additional interconnections and associated enclosures, as the solar panel DC cables need to be terminated into a box, connected to the SWA that's also terminated into that box, then the same again needs to be done the other way around at the inverter.

It’s quicker and more cost effective.

Swa to join box in loft, terminating PV roof cables.
Swa at inverter into DC isolator.

Oldgreybeard wrote: ↑Sat Nov 26, 2022 3:56 pm

AGT wrote: ↑Sat Nov 26, 2022 3:25 pm Use SWA cabling easier then metal conduit

True, but that then needs two additional interconnections and associated enclosures, as the solar panel DC cables need to be terminated into a box, connected to the SWA that's also terminated into that box, then the same again needs to be done the other way around at the inverter.

Worth thinking about. Is a bit cheaper than 4x solar cables plus flexible conduit (£2.62/m vs 4 x 52p + 99p. And it can go all the way into my existing DC Isolator at the inverter, so would need only one JB or ideally another isolator in the loft space, not a great expense.

But I had suggested SWA to a different installer and he said he would prefer to do it as 4x solar in flexible conduit as easier to install and smaller bending radius.

Would have been happy to go with him, however he said Edmundsons' solar division had no rails atm. So he was waiting for a new panels and rails supplier to start up in mid October with £Ms of stock (who they?). Since when he will not answer emails or his phone, I even pointed him at Midsummer's kit builder page with a suggested BoM. On the whole I would prefer to use a local tradesman but there are limits.

My personal view is that many electrical problems arise at interconnections, so the fewer of those there are the better. There's often more than one way to do something, and over the years I've learned that the simplest and least complex often ends up being the most reliable. Others may well hold different views.

Oldgreybeard wrote: ↑Sat Nov 26, 2022 4:55 pm My personal view is that many electrical problems arise at interconnections, so the fewer of those there are the better. There's often more than one way to do something, and over the years I've learned that the simplest and least complex often ends up being the most reliable. Others may well hold different views.

Yes, agreed. And bringing the two strings back individually to the inverter is better still as it provides a level of redundancy - in the event there is a poor connection I lose only that string.