ASHP and Solar PV, are they worth it? - my experience and data

[jaminko]

@apples1500 I'll check to see if they've got any records. They've got some issues with damp, so it may need to be removed and redone in places but there's some other things we need to try first.

 

[jaminko]

@apples1500 I could have sworn my Dad told me they had lime render fitted fairly recently. Now he says they just had some "plasticky" stuff added on top of the existing render (probably concrete, 'cos it has been there since they bought the house in 1982) about 18 months ago.

 

[alpinehi]

@ghaynes I'm interested in having a home as efficient as yours... how did you get it? Did you have it built to spec, or from a developer?

 

[ghaynes]

@alpinehi The builder's are neighborhood friends that built their own home to a very similar standard. They bought an old barn conversion in our neighborhood, tore it down and split it into 2 plots. We reserved the first plot and the 2nd one is under construction still.

There are definitely new build developments following similar eco principles but I couldn't tell you where those are. I'm sure a quick Google will give you some results

 

[wodan]

@ghaynes I seem to be seeing the word 'passivhaus' used for these sorts of new builds so you could search for that.

Also just wanted to add another thanks to OP for this amazingly thought out post

 

[apples1500]

@wodan Passivhaus is a specific green building standard (I think originally from Germany), it would be a good place to start, and probably one of the most well known of the ultra efficient design standards. That said a lot of good efficient buildings may not be Passivhaus but could still be very good buildings.

 

[wodan]

@apples1500 Aha gotcha thanks!

 

[cg828]

@ghaynes Thanks for this writeup, it's timely as we're getting solar panels and a battery installed soon. Our 1970s house isn't as well insulated as yours, but it's got about as much as we can.

One of the things I'm interested in is automating things to come on more when there's lots of spare solar power, e.g. looking to trigger the immersion heater when there's available power to stop the boiler kicking in.

 

[ghaynes]

@cg828 Another user mentioned Home Assistant which is a very open source sort of platform for home automation. There's literally thousands of apps and tools that the community has developed to work with different smart home devices.

You could in theory have something set up that triggers your immersion heater to turn on (basic smart switch?) when battery charge is X amount or solar output is Y amount.

 

[cg828]

@ghaynes Yep that's the plan, I need to get solar input and battery status into home assistant somehow, my expected inverter has a bunch of data ports I'm hoping to use there.

I've already got HA controlling some other bits, and I'm also trying to get it to work with some TRVs so I can get better zoned heating. It would be good to not worry about heating the rest of the house when I'm WFH in my study.

 

[churchstumblingblock]

@cg828 Check out ESPHome for cheap microcontrollers that interface with HomeAssistant

 

[cg828]

@churchstumblingblock Yep I've got those too, some temperature sensors, a power monitor clamp and a couple of displays. My bedside clock is an esp32

 

[churchstumblingblock]

@cg828 Nice! I've got a bank of solid state relays that I use to toggle various things on or off depending on temperature/solar input/battery SOC etc.

 

[cg828]

@churchstumblingblock I was looking at those cards with a bank of relays on, but I'd need a sepearte controller and power supply in the airing cupboard. I spotted a din mounted ZigBee relay on Alixpress, so I'm going to give that a try.

 

[javi19]

@cg828 Myenergii solar diverter may be the device for you.

 

[cg828]

@javi19 That's an interesting looking device, but I've got home assistant running and a Raspberry Pi ready that can connect to the inverter, so I'm going to monitor it all locally.

I've also got a ZigBee relay ready which I'll hook into the emersion heater.

 

[javi19]

@cg828 I’m in the process of getting a air source heat pump, Tesla powerwall as well as increasing my solar PV system, from the research Iv done each device uses a CT to monitor production and usage and from there you should be able to set out a hierarchy I.e if the suns out and my house is fully powered, powerwall is fully charged then the solar diverter automatically switches on the immersion heater until such time the water reaches the pre determined temperature or the house load increases.

 

[cg828]

@javi19 Some sort of heat pump will probably be in my future, but for now I'm keeping my ancient but simple gas boiler ticking over until it becomes uneconomical to repair.

 

[javi19]

@cg828 Also something to bear in mind is the current carrying capacity of your zigbee relay. If that’s the route you intend to go down be aware just make sure that it’s able to take the load. Good luck, I’d love to hear how it pans out for you

 

[cg828]

@javi19 Yeah, indeed. TBH it's some random component from Alixpress, and I don't trust it to handle 13A (even though it claims to be rated for 16A) my plan is to get it to switch a chunkier more trustworthy relay.