JohnMo

But in the case of a large array say 6kW and a small inverter 3kW or an inverter that can limit export, you could have 6 kW DC, the inverter will waste the rest as heat

A timber framed house is normally encased in 4" blocks, or bricks. Nearly every new house in Scotland has been timber framed for the last 30 or 40 years. Use cellulose, wood fibre or dense Rockwool for best performance, PIR will give little or no sound deadening. Windows will then be where the noise comes in.

It is in Scotland I believe, not sure about anywhere else

What is the DHT22 tied into to signal the MVHR to go into boost?

If you want to use for MVHR or similar, it looks the same, but internal wall is anti bacterial treated to stop nasty stuff from growing with the correct semiflex duct. Normal underground stuff is a little stiffer and not treated.

Exactly what is your roof buildup currently?

Go on your local council website they should point you in the direction of all the rules. The Scottish rules are different from the rest of the UK. Ultimately the rules come from SEPA. But there are other agencies sitting beneath SEPA.

Could you use a Shelly EM plus 50A clamp on your inverter output. Once output equal to xx, switch power to immersion, when below xx switch off immersion.

No different stuff. Use the excess DPM for covering sand etc to stop it blowing away or wood to stop it getting damp while waiting to be installed.

As Joe90 and ProDave say, DIY is the only way to go. Batteries way to expensive, cost per cycle still way to high. If you have an ASAP you can triple your useful output of your PV system. PV also covers your home background daytime electric usage for most of the year.

You will need a heat loss calculations to determine if the existing boiler is ok or otherwise. No need for actuators, you will need a pump, mixer valve and wiring center. Once thermostat is no longer calling for heat the pump will stop. Wiser thermostat looks an expensive way to control a couple of loops and you possibly need to use the UFH controller instead of a simple wiring centre. The mixing valves are designed for that.

Something like Rockwool flexi.

Option 1, you include a DPC below. An option maybe to apply DPC, insulation, the concrete. Attach UFH pipes to the insulation. 2. How deep are you floor joists and how much space below to ground. A better option would be to insulate between with a dense Rockwool, more forgiving to install than PIR. Use aluminium spacer plates to carry the pipes. 3. Similar to 2.

Black is great at absorbing heat, not sure if you have a black coating out the outside face of the blackout blinds. We also have white internal blinds and they have a great effect at keeping the sun's heat at bay. Not as good as external blinds but can certainly keep the room cooler by 3 or 4 degrees when closed.

The issue with ventilation is, to get full output you need some airflow at the rear for cooling. GSE trays do include ventilation. Even without cooling it is at max output when you may loose a few percent in performance, so 20 or 30 days a year, for a couple of hours a day if facing south. Not something to worry about.

Don't think my floor has seen over about 34 degrees, never saw the reason, house just got too hot at that temperature. Normal max temp is about 30 deg and that's for batch charging the floor. Think you really need to run to assist drying the screed. Not sure there is much point in the summer, especially with air temps in the 20s for a few months anyway.

Outer course of blocks/bricks replace with thermolite blocks, keep the 20mm compacfoam or just replace with PIR, not sure it's there for any structural reason at the threshold. Or replace the compacfoam/cast concrete details with a full depth compacfoam and thermolite outer skin.

If the cylinder is unvented, that needs to be done. Not sure what gets done on ASHP other than making sure it's not full of of leaves etc. has no leaks or not making noises it shouldn't.

Avoid flexible, unless pulled taught. Use hard pipe and elbows, will give a better performance from fan and less noise.

Mine is 50mm which is way to thin, more the better.

Use your phone, instead of a router, or sit the the 4G router in you car, powered from your car.

Not good

As above, but think you meant to say is you have multiple loops on each floor and you want to operate each floor as a single zone. On the manifold, each loop will have a flow meter and isolation valve. You don't really need to have an actuator. The thermostat will call for heat and start the UFH manifold pump. The mixer valve will limit flow temperature. You need to then balance the system so each room is at the correct temperature, so to increase temperature you give more flow, to decrease temperature less flow. No need for floor sensors or that much complication.

Do you also have historic England/Scotland etc consent. We fell fowl on a house, where planning said go ahead, so I assumed they had talked with historic Scotland, but they hadn't. How big is large ish? Sash or different windows

Quick rough sketch