[meldrewreborn]

@NHOJ
i’ve a relative who lives in the Churchill devolpment in Pinner- about 30 flats. Their ASHP isn’t noisy and delivers unmetered wet heat to the flats, which are then billed via the management charge.
visit nearby developments by the big boys- imitation has benefits.

[wizzo227]

Some of you have noticed that the Enormous Heat Pump solution is not always ideal and costs a lot of electricity, especially if always on.

I did something else, starting from 2kW(peak) of solar panels often (not always, and daytime-only) having more than 0.5 kW of spare generation.
For an energy budget of "a few kWh" on "a few days per week" "daytime only", I got a small air source heat pump for one room, which really is exactly a reversible air-conditioner. That uses 0.7kW(electrical) to make up to 2.2kW(thermal). In autumn, I open the door from the living room to the stairs, activate the heat pump from 10am until 2 if sunny or less than that if less sunny, or not at all if warm enough already, and I get as much heat as possible from free rooftop solar electricity. In winter, I close the living room door to keep more of the collected heat down there.

That is a partial solution; I still use the gas combi boiler and conventional gas central heating, but not a lot; averaging 4.5 kWh/day of gas use at present. To get this to work, your starting point has to be from a house with adequate insulation.

This week, I've not always been in or the weather was not sunny, so the small heat pump has only been on for about 4 hours in the week, using gas central heating instead, on for only a few minutes and only when needed. 18 to 18.5C is my usual indoor temperature for winter except while heat pump is running, which gets 21C in the living room.

The collector for the heat pump is intentionally located in the sunniest corner of the garden, so that it is moving heat from moderate outdoor temperature to moderate indoor temperature.

[retrotecchie]

@wizzo227

Can I ask a question? Is your 2kW solar array grid tied, or is is a completely standalone system?

[Plantagenet]

@wizzo227

So your ASHP is an air to air unit ?

[wizzo227]

@retrotecchie
The 2kW(peak) is conventional grid tied, through a Sofar inverter.
I do have a couple of other solar panels in the back garden but lets not complicate this thread.

[wizzo227]

@Plantagenet
Yep. what I call a "small air source heat pump for a single room" is a ten year old Mitsubishi air-air heat pump with a blower high on the wall in the living room and a collector outside, just like air conditioners. CoP of 2.2/0.7 is a bit over 3 at best.

[retrotecchie]

Originally Posted by wizzo227

@retrotecchie
The 2kW(peak) is conventional grid tied, through a Sofar inverter.
I do have a couple of other solar panels in the back garden but lets not complicate this thread.

Indeed, because I've been working in on-grid and off-grid solar for about 20 years...and don't want to bore the punters with the details either!

[wizzo227]

Some things I never get bored with. Better bicycle time to work? Pew pew pew more space invaders ? zm zmm zmm more solar power.
Suppose that we do complicate this thread as much as you like, what's your favourite tweak ?

[retrotecchie]

@wizzo227

Using the right type of panels is the best tweak, for me. Not having a grid tied system but rather a grid fall-back is the next best, and for every 1kWp of PV, installing 1kWp of ETTC comes a close third.

[wizzo227]

Sunpower E19, roof installed in Oxfordshire in 2012 (the installer said that he couldn't get E20's at the time).
plus Kyocera KD235's obtained from Machynllyth in 2009 for back garden messing.

I run grid tied so that the MPPT (maximum power point tracking) is always at-best irrespective of my not finding a local load. To minimise whole street CO2e would be my aim, but that should need net metering at the substation and cooporation amongst other households, so this year no chance. I am mindful to aim to export and import as little net power as possible; if there is spare solar electricity I'll switch on a 0.5kW nasty electric heater if doing that will save needing to with bought electricity at night time.

What does ETTC stand for ?