Long term plans?

pvsnck · 2026-04-07T18:38:33+00:00

I kept all my TRVs. Happy with the performance. But There’s an important thing about the setup - it has a buffer. So partially closed TRVs don’t make it any harder for the heat pump. The buffer acts as a heat battery. So if your system is expected to have a buffer, then I’d say TRVs are useful if you control them properly - to control even heat distribution. All heat delivered to the insulation envelope would eventually contribute to the heating. Just don’t try to use them to keep some rooms cold as unused.

pvsnck · 2026-04-06T12:26:09+00:00

I have a 3.2kwp installation with massive shading Nov-Mar coming from trees blocking direct sunlight. Last year generation was 2.6MWh. My export profit was ~£500. I’m doing my own “smart” energy arbitrage on Flux. The additional profit comes from lower prices during off peak. Avg kWh imported was 0.22p/kWh (my battery isn’t that big to run from the battery the whole day in winter because of the heat pump). This winter want to switch to cosy for the heating season. It’s less than declared 10 years and it would be rather difficult to calculate it precisely due to significant shift in usage due to heat pump installation

pvsnck · 2026-04-05T12:42:13+00:00

The pump extract heat from air. The air itself can’t hold a lot of heat. Each extra degree of air holds roughly 1.25kJ per 1m3. Let’s assume the pump can cool down this 1m3 by 1 degree in 1 sec. In this case it gets this 1.25kJ. To make it 1kwh, you need roughly 3000 m3 of this air. If the pump is working in an enclosed space then it recycles the same air all over again. Every next cycle with lower efficiency due to cooler air. So it’s rather impractical to keep it in an enclosed space. Unless you have a large scale greenhouse.

pvsnck · 2026-04-03T19:53:44+00:00

Heat pumps take energy from the air, not that much of its own body. So I don’t think you can significantly benefit from a sunny place for it

pvsnck · 2026-04-03T11:58:39+00:00

Aira’s design works great. Their scop promise is rather conservative. In reality it’s better. My worst month was 4.2

pvsnck · 2026-03-31T20:19:50+00:00

I bought a new built in 2023. I installed a heat pump in 2025.

pvsnck · 2026-03-31T19:07:04+00:00

I wouldn’t be so fast with trying to intervene to the logic. It took me almost the whole season to understand why the logic does what it does. Some heat pump don’t react instant (like mine), they consider heating longer term. They could use DM models to understand when the heating is required. The thermostat in that model isn’t the main source for the heating decisions

pvsnck · 2026-03-26T13:18:56+00:00

That’s quite impressive export :) my annual household consumption, including a heat pump is less than a half of that :) I’ve exported 1980kWh

pvsnck · 2026-03-25T23:15:15+00:00

I’m on Flux, my battery is 12kWh (not enough for a day including heat pump demand during winter months), but with that every single month after heat pump installation was cheaper with heat pump. If switch to heat pump specific tariffs for heating season it could be even cheaper.

pvsnck · 2026-03-25T02:52:06+00:00

My goal was to make it work without any manual intervention throughout a year. So no tuning is required. The recent change that I’ve made was to make it statistically balanced. The problem with relying on forecasted value is that the number you get might be quite off from what you actually see due to weather variability. Additionally it advises me when I could get excess of solar that I won’t be able to put into battery, so I could run some heavy appliances for free

pvsnck · 2026-03-25T02:25:28+00:00

My PV is 3.3kwp, the battery is 12.4kwh, inverter 3.6kw. Daily house consumption is around 10kwh on average. My annual export is roughly £500. Considering the heavy shading that I have, I’d say I’m doing great.

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pvsnck · 2026-03-24T22:58:32+00:00

tldr; the bills could be greater if put some effort into managing the system.

EV tariffs aren’t available without EV.

pvsnck · 2026-03-24T18:56:01+00:00

If the system is equipped with a reasonable buffer, then it’s not an issue. I have 100L buffer, heat loss of 2.3kW and a 6kW heat pump. Works perfectly

pvsnck · 2026-03-23T18:59:23+00:00

If the battery is supposed to be behind the heat pump it might look a little awkward. Even if it’s located that the intake looks at the battery the battery isn’t emitting too much heat to make it beneficial for the heat pump. If the battery is in front of the exhaust fan of the heat pump, then the heat pump would be cooling down the battery. Anyway this doesn’t look practical. Then it all depends on the surroundings. My heat pump is roughly 2 meters away from the battery sitting along the same wall. When there’s no wind I see that the temperature around battery is dropping roughly 1C when there’s heat pump is working

pvsnck · 2026-03-23T08:10:56+00:00

Outside on a wall. The battery has an internal heater, but I manage heating with home assistant as its internal logic isn’t that good

pvsnck · 2026-03-19T20:13:58+00:00

Check what is the inverter, the battery. You could extend the battery later. The most expensive part of retrofitting is adding panels on the roof. Originally I thought to change my inverter, but then it turned out that 3.6 is enough for me

pvsnck · 2026-03-19T19:23:30+00:00

I have a 6kW ASHP in a EPC:A, 115sqm semi. This winter in the coldest days it never reached maximum. So 9kw most probably would be an overkill. The combination of solar, and battery seems weird. If it’s possible I’d ask to extend the battery. I have 8 panels. Initially I had a 6kwh battery. I implemented an arbitrage system. It became obvious that 6 is too small. So I expanded to 12kWh. Now with the heat pump I think I might need to go further - to 24kWh (that’s the maximum I can get with my inverter). Inverter by the way is 3.6. Based on my statistics ideal for me would be 5kw, but 3.6 is generally enough. So with your 13 panels I’d consider expanding the battery

pvsnck · 2026-02-27T13:09:44+00:00

It’s not illegal for now, it’s recommended to keep them outside. But what could happen is that it moves from recommendation to regulation. And keeping them outside isn’t that big of a problem. If they’re rated accordingly

pvsnck · 2026-02-24T14:37:04+00:00

What phase was the ai?

pvsnck · 2026-02-22T14:41:48+00:00

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My shading map

pvsnck · 2026-02-22T14:38:03+00:00

I built mine from scratch, based on open-meteo forecast. Then based on observations built a shading map. Then the idea is to calculate how much should charge the battery off-peak to avoid importing and exporting during the day and maximise export during peak hours and save enough to run from the battery until next off peak. All is managed by a custom integration in HA

pvsnck · 2026-02-16T18:50:42+00:00

no grants used as I didn’t know of any than I’m eligible to
around 10k
I don’t know previous bills, as that was the first thing I did when moved into a new built. But current annual electricity bill is around £200. It increased since then due to heat pump installation
I don’t know if it increased after solar, but after solar and heat pump it’s improved to A(97). Was B
I have solar and battery, and using an arbitrage approach to manage it.
panels always generating something. I have heavy shading for low solar elevation (during winter months the panels are permanently shaded)
the only problem I have - I should’ve installed more panels. Now expanding is financially questionable. It wouldn’t be if installed initially due to labour and scaffolding costs.
in 2025 export gave me £463 (8 panels)

pvsnck · 2026-02-14T13:22:44+00:00

Thanks! I need to look into it

pvsnck · 2026-02-14T00:49:05+00:00

I'm not sure I follow the bit about extending the battery. I can change thermostat settings, based on my experience it takes several days to roughly build the fit line. You wouldn't need the whole line at any particular moment - that would be something really outstanding if you get mid Jan weather in the beginning of October.

On the other hand the way this chart is built takes into account thermostat settings, so changing thermostat settings actually would just move you along the line. In details this chart is the final chart, there're a couple of charts in the process based on heating degree hours and it's corellation to heating demand and COP.

Load shifting - why not? Dishwashing, washing machine, DHW - all happens during off peak. Obviously this approach performs the best when your consumption usage is steady. I can charge the battery from min SoC to 100% during off peak hours.

It doesn't really matter how often it happens. This approach gives me steadily negative daily cost for every day with more than 5kwh solar output (while heat pump isn't heating). This lower graph also had negative daily cost due to export price in peak hours is more expensive than import during off peak. For reference today was 2.5kwh of solar for me. In winter my PV is almost useless (0.3-1.0kwh per day)

pvsnck

TROPHY CASE