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Depends how much light hits the other side of the panels. If located on a dark roof, not much light will make it through (I think some does through the gaps between cells). On a angle or as a shade over a structure with light covered ground as a reflector I believe it can increase output 10-20%

Yep, our governments (whatever party) so often tend to try an bullet-proof everything and it just ends up making for complex policy. Often keeping it simple and accepting some sub-optimal outcomes at the edges is the better policy. Now, if only we could undo decades of this in building we could make building much easier. Governments keep adding layers on layers to try and control policy outcomes, when more detailled building control could produce similar outcomes with much less cost.

I'm not really the right person to help but as no-one more knowledgable has spoken up. Whats the fitting at the other end of the flexible pipe? Can you remove and show? I hope someone more knowledgable will be along soon.

£400-500 kWh does seem crazy when the battery itself can be had for ~£110 (assuming you already had the inverter that supported adding a battery). The install is adding a few cables and configuring the inverter, it's half a days work for 1 guy at most. The battery itself comes with fuses and isolators I believe.

Good point about roundtrip efficiency. Went down a little rabbithole looking at this. Looks like >95% is what to expect new (with 98-99% commonly claimed). Given the cost of the battery, even if it only did 4000 cycles and efficiency dropped to 80% round trip near end of life, I suspect the cost is still easily below your 10p/kWh mark.

This Fogstar battery (https://www.fogstar.co.uk/collections/server-rack-batteries/products/fogstar-energy-seplos-48v-16-1kwh-solar-battery) is £109/kWh, they claim 8000 cycles with 80% discharge (I think 8000 cycles is quite a common claim these days). If I've done my maths right thats: 109/0.8 = 136 136/8000 = 1.7p/kWh The batteries themselves likely aren't an issue cost wise. Installation, age related capacity reduction, etc, makes things worse but still worth investigating.

If you are building using the same construction techniques as the main building to practice, why not go through BC as practice of those elements? BC might point out something that causes you to avoid a costly issue for the main build. If its concern over making detailled BC plans, why not just do it as Building Notice? (seperate from main build)

I misread this the first time. I think you are right. Probably can choose which part to unscrew.

They look the same to me. Looks like the braided pipe is a standard fitting and the should unscrew from the rest of the assembly. The brass pipe on the new one has notches on it and I think whoever fitted the original cut the pipe down to a shorter length at the notches.

I've seen other people (mostly renovating) who having to deal with the builders waste left in joists. It's not a nice job, even small changes (electrical/plumbing) at a later date are gonna bring up a lot of dust (and one thought the waste between the joists was causing dust problems even before they started renovating though how accurate this is IDK).

I think the recent changes to PD has removed this: https://mcscertified.com/new-permitted-development-rules-in-england-air-source-heat-pump-installations-must-now-comply-with-mcs-020-a/#:~:text=On Thursday 29 May 2025%2C the UK government,pump from 0.6m3 to 1.5m3 for dwelling houses.

Can't comment on water proofing or anything but I believe its fairly common that the roof structure of old roofs isn't necessarily strong enough to support the added weight of solar panels, so may need redoing for that reason alone. I'm not sure the environmental benefits of solar would really stack up if you have to replace a perfectly good roof to install them (maybe if you re-used the slates).

The government has announced they are looking to streamline the planning process for small sites. Most notably removing the involvement of the committee for sites <0.5ha/10 properties. Worth keeping an eye on: https://www.gov.uk/government/publications/planning-reform-working-paper-reforming-site-thresholds/planning-reform-working-paper-reforming-site-thresholds

Interesting. Daikin does something similar for blocks of flats. Though thats a single unit installed where the boiler would be and will do hot water too. https://www.daikin.co.uk/en_gb/solutions/collective-housing.html Not sure I'd want the noise of the heatpump in my bedroom. Would expect it to be much noisier than a normal FCU.

This may not be in your budget but a route to look at is a small residential plot that backs onto a field. You'd obviously have to make two purchases and the farmer will likely charge a premium for it but it might offer a route around the planning restrictions. I don't know how realistic this is but has been an option I've been looking at myself.

Interesting. All of my valves I can press down manually (no tools). It's stiff sure but definitely movable by hand.

Is the plunger on top of the valve body free to move? Sometimes they stick and need manual manipulation to free up? If the valve body is new I doubt this is a problem. But not sure if you've just changed the TRV or the TRV + valve.

Given the space restrictions you have I guess the answer is no, but is there somewhere outside the kitchen where you could put your washing machine? Might open up more options in the kitchen.

I keep seeing people say that they prefer dry cold of -20/-30 to humid cold around 0. Don't think I've ever experienced dry cold and given I dislike cold I'm in no hurry to try but it's an interesting thought.

Would you mind sharing more about this? I haven't got this far yet (automation is one of those tasks I want to leave until much nearer the time) but this does sound somewhat along the lines of my thoughts.

Welcome! Reguritating some of the things I've learned by reading BuildHub over the last year or so, search the site for more details: If you build to true PassivHaus standards then you won't need much heating. Sometimes on the internet you see people saying don't need any at all but the consensus here is that you do need something, whether its worth the expense of a big complicated system though is doubtful. So think in terms of keeping things simple and the house at one consistent temperature (no zones). With UFH in a PassiveHaus the floor will never feel warm as it won't be running hot enough. Using UFH to provide mild cooling is possibly a bigger reason to get it than for heating. As far as smart stuff goes, try to think in terms of an add-on layer that all basic functions will continue to work without the smart stuff. You want the main services to work reliably (and have the ability to call out someone to fix them if say you aren't around but family is when something breaks). While many self-builders think of the project as a forever-home/once in a lifetime thing, life does tend to throw up curveballs so always keep in mind that you might have to sell it at some point. So avoid doing things that would put potential purchasers/mortgage companies off.

The release of energy is much the same. But the release of energy is not whats causing climate change. That is CO2, methane and various other gasses that act as an insulator in our atmosphere. Our planet has at times been much warmer than it is today and some of the CO2 from that period ended up being sequestered in the ground. Releasing that today is the problem. The sun blankets the planet it many orders of magnitude more energy than all the power plants on earth so the release of a little more from a buried source is not going to change things. Releasing the buried gasses do.

It's not the heat from the reaction thats the problem for climate change. The sun provides many orders of magnitude more heat. It's the CO2 (and Methane) that is providing a blanket of insulation in the atmosphere that is stopping the heat from the sun escaping. That said, the amount of concrete and steel used in a nuclear reactor means that they are a negative for climate change initially much more so than other power generation methods. They work long term because once they are built emissions are minimal. Edit to add: The steam emitted from power plants (not just nuclear) does have some effect on the local climate surrounding the plants, more fog, clouds, etc. Read an article a few years ago about how motor accidents were much more common on a road near a plant due to the commonly difficult conditions. When the plant shut down the issue went away.

I belive that NuScale has one in the US: https://www.theverge.com/2023/1/23/23567711/nuclear-energy-advanced-small-modular-reactor-design-certified Not that it looks like any sort of game changer

They did before all the Three Mile Island, Chernobyl, Fukushima accidents and the regulartory over reaction that followed. All their recent projects are equally overbudget and expensive. The nuclear industry shot itself in the foot when it chose to focus on adding redundant safety systems on top of fundamentally unsafe designs rather than pivoting to self limiting/safe designs earlier. Happening now but a lot of sunk cost.