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I agree, though my main concern is not really the fire risk itself, it's concern that insurers or mortgage providers will turn round at some point in the future and say that the roof represents a big risk now and therefore either bump the price or refuse to engage. Obviously this would be a wider problem affecting a wide variety of installs. But living in a flat I'm currently unable to sell due to cladding issues (which as far as the surveys go was installed in a fully compliant manner at the time of install) makes me especially touchy on this subject.

The point of the isolator is to break the circuit. Once the circuit is broken the MC4 connector should be relatively safe to handle. Otherwise, installing solar would be a much riskier job. An isolator on a broken inverter can still break the circuit and once broken it should be safe to remove/replace and the new inverter will be installed with the isolator in the off position, ensuring no current flows during install.

With addressable tape, AFAIK, you can set the output to 0% and get no light even though the strip is powered on. Obviously there will be some extra current draw, but I wouldn't be shocked if normal LED controllers leave the power on all the time anyway. The 4 core cables you have are thinner than I was imagining and you have cat5e rather than chunky cat6. So overall the conduit is less stuffed than I thought but still given the awkward bends over the joists less is more. @andyscotland repeated my point about spacing the joins. I suspect your 4-core cable is stranded (maybe labelled as flexible) which will make it easier to pull. That CAT5 cable is probably solid core. If you wanted to pull CAT5 through conduit then getting some stranded would likely make things easier. (Its usually used for patch leads). As a complete aside, why did you choose addressable strips over normal ones? The added cost seems hard to jusitfy for me.

It was more that I thought I've seen that some of these systems overlap/interlock the panels. Saw something showing panels being riveted in place (didn't look hard enough to see whether the panel was still removable with rivets in place but if not looked like a bit of a job to remove).

True for most systems. Some of the integrated systems might be more tricky. So something to pay attention to.

Fibre cement is one way, I've seen a fire blanket on advertised. A layer of mineral wool would be a good option and provide insulation as well, though mineral wool formulated be used above rafters is pricey and has other complications. I wouldn't be shocked if mineral wool between rafters is enough. All the above relevant to in-roof systems. On-roof systems is easier. Metal roof or tiled roof covers you. If you have a single-ply roof may need to take extra steps. That's my question too. I've seen a lot of talk about it but not found any hard and fast rules. Obviously GSE trays are fairly commonly used without the extra steps above but I get the impression things have changed fairly recently and I'm not sure where things currently stand.

I've come across this guidance talked about many times, but every time I look at it I can't help walk away thinking its not really aimed at domestic properties. It's all about installing big commercial systems. Yes, when I said MC4 connectors it was because that is the most likely thing to fail *on the roof*. Isolators are usually elsewhere, but not really supposed to be installed on modern domestic systems any more (the inverter should come with a built in isolator and that is sufficient). And knows how to use it!

It shows the concept. Lots of companies selling similar but all very industrial/scientific so likely stupid prices. Coming up blank on aliexpress. This feels like a diversion from Alan's thread so I will park this for now. I'm a long way away from actually needing this.

I went googling: https://www.beadedstream.com/a-guide-to-thermistor-strings/

Some of that might already be there depending on your roof makeup, MCS does have some requirements. Saw a company advertising a fireproof blanket to install under panels and someone posted here about GSE trays waiting for fire safety tests here and I'm going to be interested to see if the result of those tests is any change to standard install instructions. (Could cause a few problems for people who have already installed but not yet got sign off).

When you are talking about a whole roof, this might be a lot of separate thermisters and wires to manage, all routed to a central point to alarms. I'm pretty sure I saw a premade cable with 1 wire thermisters spaced along the wire. Thats why I mentioned it, install would be comparitively trivial. Been a while ago though so would have to do some searching to see if something like that is still available.

It's the MC4 connectors that get most of the blame. In theory its a standard but each manufacturer has variation which can lead to tolerance mismatch and poor joints. Also, the connections from the roof to the inverter usually need to be made to fit on site and bad crimps, etc, has apparently been a problem. Arc Fault detection in inverters is now mandated by some countries to try and pick up on these dodgy connections (not yet here AFAIK). This has been a problem that has got a decent amount of attention from MCS, etc, so I would expect any recent install here to be fairly robust against it, but certainly an area to pay particular attention to if DIYing. For my future plans, I'd plan to see if I can put some 1-wire or similar temperature probes next to every join as an extra layer of safety. (Obviously needs monitoring).

Well this is stuck in my head for some reason so another thought: why not run all these cables outside the conduit? Leave the conduit for unexpected future need. No reason to pull out existing cables if future needs require something different, just add additional through the conduit.

More thoughts: Can you tie the conduit to something straight to get rid of those bends at the joists? They really aren't helping. Really want the conduit to be very straight until it turns the corner. A Stranded CAT5 cable would be much easier to pull than that chunky CAT6.

I meant show us a photo of the cable bundle you are trying to pull, especially the lead in (where you tape together cables). Are these cables sold or stranded? In any case, sounds like a lot to stuff down a 20mm conduit in the best conditions. Can you share the 4 core cable between the two strips. Vcc, Gnd, Sgl1, Sgl2? Obviously the Vcc/Gnd would have to take twice the current?

There was a fairly stunning story I read of one of the AI's being fed an ancient binary from a DOS/win31/95 game that could no longer be run on modern computers. Instructions were to produce code to recreate the game. The game was a hobby project that had sat on someones hard disk for decades, never been uploaded online. The AI took the binary and produced an almost perfect clone in python. AI's have some stunning capabilities when it comes to coding (as long as you are knowledgable enough to supervise them). Pure vibe coders seem to keep faceplanting once things go wrong.

Just saying that the detail around a zinc standing seam is likely to be somewhat different to the version you posted about before. Zinc can be soldered/custom formed in a way that steel can't. Seems to me that you might be underestimating how much time you need to get this (plus everything else done). That is a good idea if it can be done without too much extra effort (or if it saves a lot of effort that would otherwise be spent dealing with the MHVR). If you aren't really targetting a specific size for the roof space - just enough for MHVR and maybe some other plant then there maybe options that avoid the tricky bits. Simplist that comes to mind is insulate under rather than between the rafters (losing space but its easier). Need to think about airtightness carefully though.

Show us a photo of what you have? If I were doing it I would look to space each additional cable quite a way away from the the previous join. Bundling them all together will make for an inflexible section. Are you using stranded or solid core cable?

You had another thread recently about trusses vs hand cut roof. If you aren't trying to vault the ceiling or preserve the option to build additional rooms in the roof then going for bog standard trusses is more attractive than otherwise. If planning a future expansion into the loft then I understand the placement of the insulation. If not, is it possible that the architect is working of old or incorrect assumptions? If so could be building in extra cost/complexity in other areas too. Edit: Also note your plans say zinc roof whereas another thread suggested youd choosen something else.

Given you want roof integrated solar. Make sure your roof make up is compatible. Specifically about fire resistance. I'm pretty sure I've seen that requirements have got tougher recently. Sorry can't remember more or point you to anything specific.

I'm definitely in the camp of wanting as many panels as possible (even on the north side of a roof if the roof pitch is relatively shallow). Maximizing winter production using large numbers of panels seemed more cost effective than pretty much any other energy efficiency measure (when I last sat down and did some costing on this which is a while ago). The Viridian system looks good, whether it's worth the premium though idk. Proprietary panels always a concern but if doing roof trays then you are locked into a fixed size panel whatever you do (make sure you get spares/have a guaranteed ability to replace them in case you get unlucky with a hail storm or similar). The latest Viridian panel seems pretty up to date, glass-on-glass which is good to see (as last time I looked the more proprietary systems seemed to be a few steps behind the latest panels.

What is included? Panels themselves should be closer to £30/m^2, double that once you include the trays. Am I missing something? https://www.bimblesolar.com/solar/solar-pallets/PALLET-C455

Again, not got knowledge of the specifc hinge. But just because a normal spanner doesn't fit doesn't mean its not there for adjustment. Slim tools exist and wouldn't be a surprising requirement: https://www.amazon.co.uk/sourcing-map-Galvanizing-Automotive-Furniture/dp/B0DRP7YZF9?sr=8-8 The above are cheapo ones as I know you are on a budget. Its possible they are too weak for your needs (but amazon has easy returns).

Don't cap it. Leave the other side open while you fit the stop cock then turn the stop cock off. Can be done without too much mess (outside).

It's about the third significant tangent so far on this thread. In the running for most diverted topic of the year!