sgt_woulds

I'm also not an expert, but I thought masks were to prevent or reduce the risk of a carrier spreading the infection to others, rather than protecting against infection? Without a mandate, this relied on people having a social conscience and respecting their fellows. Unfortunately, this appears to be less and less common in all societies and especially in the UK. With my customers, of all the ones I visited during lockdown when their 'carers' were there, I observed different approaches to respect for others. The patients whose carers refused to wear a facemask all died. (Two of the worst tried to forcibly remove my own face mask) Now for the conspiracy theorists types, I would present this as evidence that face masks worked in preventing infection. This would be utter nonsense as a large proportion died, even where fully masked carers and family members took all the trouble they could to protect them. Personal experience and untested, non-peer-reviewed conclusions cannot be issued as a statement of fact. I just realised that I misquoted H.G. Wells as Arther C. Clark! A brain fart, or could it be the side effects of all the Covid vacines?

The actions of those in government during Covid can be explained as: 'Any sufficiently advanced incompetence is indistinguishable from malice' Or Arther C. Clark's sentence from the wheels of chance: 'There is very little deliberate wickedness in the world. The stupidity of our selfishness gives much the same results...' Ironic, as The Wheels of Chance was all about new-found freedom, whereas for most people, the experience of the pandemic was anything but.

If you buy a Ford EV in the UK now it will be a Volkswagon. Probably better for it, apart from the stupid haptic buttons 🙂

Glossing over... and back to the OP We know who is guilty of hastening climate change, and so do they; their own salaried scientists told them back in the seventies. How can we make them pay for mitigation?

Pretty much as I expected. It is pointless to engage with Climate Change deniers and Covid conspiracists, who never provide peer-reviewed sources and do not engage with reasoned debate backed up by evidence, but cite the Great Barrington Declaration as if it was a statement of fact. As an essential worker, visiting clients daily throughout the lockdown, I experienced more than enough of the horror of the pandemic's effects. I can tell you that the true Co-morbidity cost to my customers was traumatic enough that I still find it hard to discuss. 46 of our clients died in the first week of the lockdown alone, and I stopped counting after that. Is that 'normal for the flu season'? Those who stayed safe at home, fomenting conspiracies, can never understand how truly insulting it is to hear such utter rubbish repeated, let alone as part of a general discussion on a building forum. I'm thankful that I wasn't working in a hospital where I'd have actually had to watch them die, but I can tell you that there are many thousands of bereaved family members, traumatised medical staff, carers, and other essential workers who will never forget the lockdown and will never forgive conspiracy theorists who make light of their cost. Many lessons should be learned from the lockdown, and there may be alternatives to the various forms of lockdown and vaccination schemes used around the world. But all of these should be attempted with the best of intentions - to save lives, rather than prevent inconvenience. This is something for suitably qualified and evidenced discussion between experts - not a shouting match between DIY builders...

Out of interest, which ones? Just popping up to lob a grenade...

OSB is more rigid? It may have slightly more tensile strength, but the difference is marginal, and like every material choice, the characteristics suit different scenarios. OSB3 is cheaper and generally more vapour open, which is useful if you place it inside the structure and use it as a racking board and moisture vapour-variable control layer for a 'breathing wall' system. This is common in European construction using natural insulation systems. WBP (and make sure it is WBP, as there is a lot of fake crap coming in from China) will better survive getting wet a few times and living in a moist atmosphere. Especially if you use a hardboard face WBP ply. It dries quicker when wet, and is less likely to swell if building over winter. OSB is generally fine, and will also survive a short period of being wet, but it will swell and lose its structural strength faster than WBP in the same situation. WBP is also much more expensive, harder to source, heavier, and slower to cut. If using as external racking in an exposed location in summer OSB, winter WBP. If you need something to take structural connections, then WBP will hold a screw better.

Global warming is man-made, and we do need to stop burning everything. The question is how we go about achieving that, not that it should happen surely?

Stronger and cheaper. I'll have a look tonight and see if I have any photos of the stages.

Pre MCS we had our own in-roof system that allowed the panels to fit truly flush with the tiles and worked for both new build and retrofit. It was a bit more work than a tray system but the results looked much better than other in-roof systems at the time. For existing roofs, the tiles, battens and membrane were removed. 18mm ply was fitted between the rafters to achieve a flush surface. This was then covered with EPDM and then battened and tiled around the edges to the required dimensions. Tiles could either be mucked-in, or use industrial compriband expanding tape to maintain weatherproofing. A dedicated, weathertight cable entry point was included at the same time. We used double galvanised Unistrut rails fixed to the rafters - 21 or 41mm profile, depending on the tile profile depth - with spacers to allow unobstructed run off. With panels fitted over, the surface usually matched seamlessly with the rest of the roof; this looked particularly good with all-black panels against a slate roof. One of the benefits is that the gaps at the edges were 50mm all round without any flashing details except some leadwork at the bottom of the array to lap over the eaves tiles. And of course, the bloody pigeons couldn't get underneath, unlike some of the other early in-roof designs that were only slightly better than bolt-on in terms of profile and appearance. My own in-roof panels were constructed this way and are still looking good after 15 odd years. No reason that the EPDM couldn't be replaced with a fireproof metal roofing sheet and trapezoidal fixings for an updated version of the system. Sadly, you can no longer use Unistrut for an MCS-approved system, as they refused to pay the stupidly high MCS 'approval' fees. The market was too small for them to justify compared to all the other market opportunities. The same reason that our in-roof system and bespoke slate and plain-tile fixings using unsistrut were never commercialised. Too bloody expensive to get it through MCS approval.

Sorry Rick, That's just nonsense! DC requires touch pos and neg field cables in order to create a circuit. It's perfectly safe to strip and fit one cable at a time. Even better is to work backwards from the inverter to the panels. i.e. connect the field cables to the isolator first, (with AC and DC isolators in the off position) then run them to the panels (mark the cables to ensure the correct polarity) and fit the MC connectors before plugging into the panel neg and poss connections on at a time. As long as the isolators are switched off there is no chance of arcing when connecting to the panels as there isn't a complete circuit. If you are working on an existing energised system, isolate the AC (always AC first to remove the load) then the DC Isolator to break the PV circuit. If you are capable, and the space in the DC isolator allows it, you can safely remove one cable connection in the isolator at a time. Tape them off. You could also disconnect the field cables from the panels if you don't feel confident enough in your ability to work safely. But at that point, you should really be asking a DC-trained electrician to do the work for you. I have received shocks from PV in the past, and in most cases, that was due to poor installations by cowboys. I was once passed some wet field cables by an apprentice who had connected the panels first without asking - thought he was being helpful! Boy, did he get a lesson that day! The worst shock I suffered was caused by me having a hangover... from an extremely spicy curry! I felt groggy and shouldn't really have been working (back when I was industrial abseiling, I would have walked away...) I cut through both field cables - 660v at 12 amps. I was thrown across the room and thought my heart had stopped. I was also completely blind for about 5 minutes. I decided not to continue work that day...! An unnecessary accident caused by my own stupidity in not assessing my capability to work. I have a very healthy respect for DC power, but sensible precautions and pre-agreed working arrangements are the way to go - not waiting 'till the owls start hooting before climbing up a ladder!

Can you provide a link to a website? I need similar...

As an ex-installer from before FiT and MCS was around, I have never seen a fire caused by a PV system that spread to the roof, but have certainly come accross many instances of poor installation causing DC arcing, where a fire could easily have occurred. The most dangerous period for house PV fires in the UK was in the early period of FiT introduction, when we went from being one of only three Solar PV installers in the UK, to having 100 new companies forming every month. Many of the causes were installer mistakes - this is what happens when you allow roof monkeys and 'builders' to fit electrical equipment after a day's 'training'. Poorly fitted DC connectors, incorrect isolators (AC instead of DC specific) and loose neutrals were the most common issues (for some reason, the neutrals always work loose on the AC side of PV, which is why we introduced an inspection and maintenance service to check annually). Other issues were caused by solar equipment manufacturers themselves. There was a range of DC isolators we used in the early days (Can't remember the name now) that had an IP rating that was not worth the paper it was written on. Used under ground-mount arrays - even where the panels should have provided protection from rain, they would leak and cause DC arcing. We had five isolator fires in one install, and spent the next two weeks replacing them in every install we'd done to date at our own cost. Later, ABB introduced a 'DC' isolator that was not up to high voltage DC switching either. To compound the problem, their DC isolator looked exactly the same as their AC isolator, other than a model number difference. Guess what happened? Que another round of replacements - at least ABB paid for those. I conducted many maintenance and repair visits to 'Cowboy' installs, where they had used AC isolators on the DC side. When inverters were introduced with built-in AC and DC isolators, the safety of PV systems improved greatly, as idiot installers couldn't fit the wrong equipment. The more isolation points and connections you fit to PV, the more points of failure you introduce. Some of the early 'Goldrush' inverters were also dodgy. The old iron-core transformer inverters we used pre FiT (SMA, Sputnik) never went wrong. The early transformerless inverters were prone to electronic problems, and we had a couple of the early ABB inverters nearly catch fire. Not to mention some of the cheap Italian and Chinese crap that the cowboys fitted. SMA was also guilty of causing fires. Their first inverters came with certificates incorrectly stating IP65 in all conditions. They were IP-rated, but only if mounted vertically. If more than 30 degrees of vertical, moisture would creep inside. The issue was invisible from outside - the first time we encountered the issue, the installer opened the inverter lid and a ball of flame singed his eyebrows off! Personally, I think the biggest step backwards with PV safety was the introduction of the MC4 'compatible' connector. Previously, we had used MC3 connectors. These could only be fitted with specialist tools, and we never had a single failure of an MC3 connector, as they were hard to fit incorrectly; if you didn't crimp the terminal end properly, it would come off when you pulled the rubber boot on. The only issue was some people not pulling the shroud until it 'clicked' into place. As soon as the cowboys had MC4 they could fit them with a pair of pliers and hand-tighten the plastic shrouds without proper tools. No wonder so many failed! Mechanically poor and not waterproof unless fitted with the care and attention that your average UK 'tradesman' cannot be arsed with anymore. Then, of course, you can mix them with 'compatible' connectors from another manufacturer. Utter rubbish. I still have a supply of MC3s, and routinely replace any MC4 connectors on my DIY solar projects.

Also, PIR shrinks over time and when exposed to the high temperatures typical under a roof. Even if by some miracle you get a perfect fit when installed, as it shrinks, you will get thermal bypass. I agree that flexible insulation is better in this situation. Flexible woodfibre would be better still as the decrement delay will help with overheating issues we are likely to experience ever more often. On my retrofit, I used woodfibre between cut rafters (allowing minimum 40mm ventilated airspace) and PIR underneath, fully taped and sealed, and acting as the VCL and airtightness. This was a compromise to meet the U-value requirements and stay within the structural capacity of the existing timbers. Has worked very well through the heatwaves so far, and no sign of PIR shrinkage as it is protected by the woodfibre above.

Sorry, I missed your reply... It depends on the specification of the woodfibre sheathing. Some are available with a hydrophobic coating that allows any moisture that gets behind a properly ventilated rainscreen to run off and additional membranes would not be required in most parts of the UK. If you are in an exposed location where rain could force its way into the cavity, or if the rainscreen has less ventilation (due to firestops, or behind a brick or stone skin) then it will require a waterproof breathable membrane fitted, before the battens and rainscreen go on. Ideally, a nail-sealing tape should be used between the battens and the membrane to ensure that no water can run down the wall and find its way into the insulation zone. At least one manufacturer makes a woodfibre board that is pre-bonded with membrane to make this task easier and quicker (although slightly more expensive in material terms, you save on labour costs and install time, and reach a weather-tight stage, sooner) REI60 should be possible with the correct cavity closers and detailing. The aluminium skin would reduce the spread of flame, and woodfibre - although a class E product - smoulders and self-extinguishes (unlike plastic insulations which melt and ignite, spreading fire), so you are unlikely to have a Grenfell situation. The woodfibre manufacturer should be able to advise on this, and it is better to have e-mail evidence from a manufacturer to show building control if needed.