Notes from an eco house. (2025 Update)

I think Nick's point was that large generation 3 reactors have passive safety features. Actually, I think it is part of the key characteristics of generation 3.

No, clearly a sub SMR is irrelevant to what would be useful for a city or even a decent sized town, quite apart from how it is cooled.

Perhaps only while the minority have EVs and electric heating? Will that

You would be surprised at how much transmission lines cost

No, it could not.

Type approval only applies to factory built modules of identical design and construction

I dont expect it to slip.

In message snipped-for-privacy@mid.individual.net>, at 20:54:45 on Sun, 29 Dec 2024, ajh snipped-for-privacy@loampitsfarm.co.uk> remarked:

It's a year now since I switched to Octopus, and I've still failed to persuade them to either fix my broken (for about three years now) smart meter, or fit a new one.

I'm beginning to lose my patience.

Electricity does cost more - by a factor of about 4. And perhaps the heat pump costs double to run in winter - although I doubt that, given the solar/battery.

If all else is equal, besides the eco-features of the new house, the new house should cost a fraction of the old to run. I think you're keeping at least one critical variable all to yourself. My guess is is property size - the new one is a lot bigger with masses of glazing. And there could be a fault, user error, or poor installation at play.

Just adding a few solar panels and a battery, with no cheap feed in to charge it overnight, has cut my annual dual fuel costs by maybe a quarter (I haven't gone a full year yet). If I had all of that insulating, heat pump, and heat recovery gubbins I'd expect to save a lot more. Not stay the same.

This:

RJH snipped-for-privacy@gmx.com wrote: If I had all of that insulating, heat pump, and heat

Yes, but you'd "save a lot more." whatever you were using to provide the heat.

I was surprised myself, but he assured me that that was the case.

Property went from 3/4 bed detached victorian single brick to full eco house of similar size. Big windows yes, but vert well glazed. solar gain is enormous

I've been with them over a year and never had problems with smart meter but none of their innovative tariffs suit my demand so I have stuck with their flexible offering.

Their new cosy offering would suit me but my smart meter does not have the switched output for a storage heater so that's out too.

Yes that is how I see it, in fact I believe the special EV rates are loss leaders.

Surprise me! Apparently £24.50 of the average annual bill is transmission costs.

A lot of stuff said in this thread surprises me. Apparently people are claiming the can make money from home battery storage. That surprises me. I'd have thought the generation companies could balance load much more cheaply than a home battery.

I also find it hard to understand how huge investments in insulation and new heating systems would ever be economic for me, given I don't spend that much on heating.

Well you can claim that, but I fail to see why the approval process couldn't be streamlined for large power stations with the same design. Just as construction costs would benefit from shared knowledge, as they did in France.

And yet... new technologies, construction projects do slip, it is the normal thing to happen. It seems to be a natural consequence of our investment/procurement methods. Unrealistic promises are dishonest, irritating, but it is what it is, it is the way the world works.

I agree we should race ahead with the Rolls Royce SMR project, but we need solutions now, not delayed in the hope of a magic new technology. We have had 25 years of that, and see where we are now.

A sensible thing to do might be to use government money to parallelise development stages in the same way they did with Covid vaccines.

An immersion heater would soak-up surplus PV output, better than exporting it at SEG pittance rates?

Fair enough! Be interesting to see how it ends up in a couple of years.

My sister had a heat pump installed in her pre-Victorian 5 bed detached house. Seemed unlikely to me. I've asked her (and her environmental scientist husband) a few times about before/after costs. They don't seem to know - they just say it's fine, and pay the bills.

Theo of this group seems to be doing some pretty thorough analysis, but the problem for me is transferring his experience to others.

Surely you don't need that, just a timer? Teleswitching was needed when everything was mechanical and clocks could get out of sync, but nowadays a simple electronic timer would suffice - either a plug timer or something beefier wired in.

You would need to set the timer to match the published periods on your tariff, and keep it updated with summer/winter time changes if it didn't do that automatically, but that's more or less fit and forget?

I have one of these - it's a PITA to use with a tiny screen and buttons so I wouldn't recommend it, but it sits on a DIN rail and could easily live inside a consumer unit:

Theo

I was taking a casual look at the Givenergy forum the other day, and noticed a post complaining about the running cost of their (same as mine) solar inverter

- 80W/hr. I asked if that was constant or varied by the 'work' it was doing but no reply.

I was surprised it was so high - no mention of it in the initial calculations, just efficiency. Certainly explains why my ambient consumption jumped up after the solar was installed. And the cost of running the thing will wipe out most of the export - if those figures are correct.

The takeaway is that for the same power OUTPUT gas is slightly cheaper than a heat pump due to the inflated price of electricity.

Which the renewable lot claim strangely is 'because of the high price of gas'...

My guess is that if you are running a cheap peaking OCGT plant for an hour a day you need to raise your prices to make any money.

So gas generation would be cheaper if there were no renewables....

Be that as it may be, but I reckon that their low overnight rates have saved me about £1k in the last 12 months. Moving to Octopus generally has also saved another £1k agoinst the charges of my previous supplier.

Yebbut that only 'saves' if you were planning on heating the water with the immersion anyway. If you were going to use a gas boiler (or an ASHP) then the actual value of the heat is more like 6p/kWh not 25p.

And if you're on the SEG you're likely doing something wrong as there are better tariffs available, although probably when it's a sunny June midday the export rates are going to be low because everyone else is also exporting, so diverting into immersion could make sense then. But better would be to store in the battery and use it in the evening when peak rates are higher.

There are so many variables it's very hard to project what your 'return' might be in the future, even if you can get a feel for how things work right now.

But I think solar makes a lot of sense if you can keep the install cost right down. eg if you go here:

If you can DIY and you can keep roof access cheap, then that reduces the payback time to a few years even with the most pessimistic assumptions and making no attempt to optimise your consumption.

Rule of thumb is that every kWp generates 1MWh over the year. So that system would generate 5000kWh per year, and even if you only used a small percentage of that optimally then payback would only be a few years if you were able to DIY the install (or contract out the minimum that you need help with and DIY the rest).

Theo

Does it feel warm? It's hard to lose 80W, that's like an old hot lightbulb. You'd expect it to either be hot or running a fan to vent the heat as warm air, like a PC.

I can't see how it would lose that other than as overhead when converting - at night say it isn't doing very much. At full tilt if the inverter was say

Does the manual give any efficiency curves?

For baseload I wouldn't be surprised at say 10W extra all the time, just to run all the stuff. But 80W sounds a bit much.

Theo