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Impressive!

Would have thought you could load shift the hot water and bulk of heating, especially as you are targeting most usage during summer when heating less needed?

You've said stuff like this a few times and everytime I try to understand what you are getting at but I'm afriad I'm not really getting your point. In case it doesn't come across in the way I indend, the below is not having a go, just trying to understand your argument. The pipes buried in concrete (at least in low energy houses) are going to be able to cope with almost anything thrown at them and will last a very very long time.* A lot of what we discuss here is how to get the maximum efficiency out of a system and the theme here to achieve that is minimum controls, low water temperature, system on most of the time with weather compensation (a technology that has been standard in all heating systems in other countries for literally decades). Even if you add lots of fancy controls on top of the basic system, the fundamentals of the system are such that you should be able to remove those controls and still get a very functional system. Similarly, if the heat demand of the house increases then worst case you need to up the flow temperature in the pipes to compensate. Again, most of the designs talked about here for new builds are based on very low temperature heating. If you can output sufficient heat with the water in the pipes flowing at less than 30oC then if some cataclysimic climate change happened and suddenly we were all living in -20C then upping the temperature in the pipes to 40-45C should still be able to adequately heat the house. Obviously if people want to extend the house then any extension would need work, but thats no real difference to any other system. If you have a low and slow design the system shouldn't care too much where the walls are if they needed to be moved. I do think that any 'smart' stuff added to a house should always be removable while maintaining the basic function of the house. Maybe you lose convenience or a little efficiency, but things should still work. Again, in the vast majority of cases, the systems discussed here are of the type that could be removed without significantly reducing the basic function of the house. Therefore, it is easy to offer any future buyer of the property the option to have all smart systems removed before they complete any purchase. So these shouldn't have a negative impact on the price of the property. * Plastic pipes don't corrode and UFH systems should have much less metal in them overall reducing corrosion of other parts and build up of gunk. They can be flushed if there is a problem. Even in the unlikely event of the pipes developing a problem, retro fitting radiators or even electric heating to affected rooms would be unlikely to dramatically change the sale price of the house. I do see a concern about whether rafts can be relied on to last as long as traditional foundations, but this has nothing to do with UFH.

If you claimed a self-build CIL exemption for your build and move out before 3 years after completion you may become liable to pay CIL. It can be a lot of money so check this as well.

Lots of inverters (not all) come with a controllable relay output that can be used to signal things like excess energy available. Your Panasonic likely has an input that could be programmed to set a higher temperature when there is a signal present. So combining these two could likely do what you suggest without any extra geekiness. But still requires some set up and knowledge. Whether it’s worth doing vs doing the work to export and sell excess to the grid idk. A 3.6kw system with 5.6kw of panels should generate a decent amount of power that likely justifies the £250 charge to get export approval with Octopus (for a non MCS system).

A single inverter with two MPPTs will handle two strings with different condition (and importantly different voltages/number of panels).

The doc suggests a £2500 govt contribution to an overall £4500 cost so not free, just discounted. Bet their require MCS certification to do the install though so there goes your saving!

I don't think most people put anywhere near that much thought into their systems. We on this forum are not representative. I can see this happening, but not because the bulk of people have analysed the costs but through inertia. ie, "the boilers broken, lets just use the AC for now and decide what to do with the boiler later". They'll stick on the immersion for hot water and then forget about it.

Nothing in the doc that Simon posted suggests that the new A2A element requires removal or disabling of the old system. To me that seems like one of the biggest changes. In the end I suspect this change if stands as is likely means almost everyone just installs new A2A and uses the cooling but continues to use gas in winter (possibly less). Not sure how MCS will work with A2A stuff either. Most of the existing MCS contractor base is not f-gas and don't think there is much crossover to A/C installers.

Now show a modern equivalent mediteranian design. It will have large windows too (though also plenty of shading/overhangs most likely). Old houses has small windows because glass couldn't be manufactured in large sizes. Once large glazing panels became viable people everywhere wanted to use it with varying levels of solar gain mitigation, from brute force carbon intensive mechanical forms to passive approaches.

Interesting document. Firstly, want to make clear that my comments earlier are in relation to summer generation offsetting any additional cooling load caused by this policy change. I've not been thinking about winter generation at all though not sure that makes much difference for our conversation. Secondly, the document shows significant reductions up to 2030, which again aligns with my comments. Beyond that I'm surprised by their predictions but also note that they are basing their graphs on agreed plans. It's inevitable that more distant renewable projects haven't yet been approved as most renewable projects are relatively quick to implement. Nuclear being the only real long term projects that might show up for 2040 predictions at this time.

For voltage you want the string max voltage to be close to the inverter max voltage. That way you get startup to happen even in low light. If your startup voltage is too close to string voltage you will lose a lot of generation in lower light conditions. Up in scotland I'm guessing that is a very significant chunk of generation. The current spec you want to look at is short circuit current. The MPPT current can be exceeded as the MPPT won't draw more than it can handle. If you can supply more current you effectively cap generation once the current reachs the inverter limit. But this means you get more generation in less than ideal conditions with the trade off of limiting maximum generation.

Just had a quick google and first hit with displayed prices suprised me. Combination insulated shutter with fly screen, automatic operation, coming in at less than half the price of pure fly screens I've looked at before. Feel like I've misunderstood or misremembered something.

It's one of those things I'd like to see trialled. Certainly the behaviour of the previous governments (which in this case I think means civil servants rather than ministers) has been to distrust the population and assume that allowing them to install something that can cool will lead to them using the cooling feature and still falling back to the traditional gas system for heating. Personally, I'm not a fan of air based heating (or cooling) systems. I've never experienced one where I'm not disturbed by the noise when sleeping and I can see that pushing a lot of people to maybe install a system, use it partially but also keep relying on the quiet, hydronic, system much more than any government funded scheme would like. But I think it's worth trying, Americans tend to have air based systems and they don't generally see them as an issue.

Exactly, they are contracted to be on even if the power isn't needed. Changes are being made to eliminate the need for them in the not too distant future. 'Spinning Reserve' is a somewhat outdated concept. There is nothing to stop inverters from covering this function, the issue is that the software in inverters has been programmed to cut off if the grid gets out of spec rather than try to compensate (the grid didn't want to deal with the complexity and when renewables were new they didn't need to). Now we have more renewable generation and batteries on grid, inverter systems can take over this aspect of the grid. (of course with careful planning, testing and synchronisation).