Discussion ... ASHP(Air/Air) with Solar pv ....

Martyn1981

Coastalwatch wrote: »

Our "living" room is some 28 sq m with a south and west aspect. Tables suggest we'd need an ASHP of some 18 Btu's or 5kw capacity. 12 Btu's capacity may stuggle to cope!

In planning a 6.84kw array I suspect I might need all of those to supply enough free leccy in the shoulder months!

Hi, ours is 3.5kW, and and I've had more than enough spare for a 5kW most of the time, remember the kW rating is the output, not the input.

Typically I need around 800W+ to avoid import with the ASHP and the telly on (plus the usual 'stuff' in the background).

Coastalwatch

Thanks Martyn, that's really helpful to know. According to the generation forecasts for my array and taking average output per hour only in the shoulder months then March should return 1.27kw/hr and Oct at 1.05!
I appreciate that some days the figures will be less balanced out by there being more on others.
I was wondering if I'd over spec'd the ASHP unit but suspect if I also wish to influence adjoining rooms then it's better to be over than under, assuming the array will cope without resorting to importing from the grid!
Not ever having had such a system(either SP or ASHP) your figures from real life experiences are certainly reassuring to have. Thank you.

tunnel

Thank goodness for ASHP. My boiler sprang a leek at 4.30 this morning so i had to isolate and leave it off till the gasman could get. Luckily the house was still warm(ish) so went back to bed but at 8 this morning i turned the heating side on on the ASHP and hey presto......warmth and not a penny of electric paid for, gasman arrived to a nice cosy house at 9.30 and all the family sat there in shorts and T- shirts. Don't you just love PV and all the bits that go with it.:cool::beer:

Martyn1981

How was this winter for everyone? I've got my 6 month figures for leccy and gas, but don't know if they are good or bad really, as I don't know how the last 6 months compare to other years weather wise.

So my figures are (for October to Mch):

Leccy up 158kWh v's the previous year (and best year).

Gas came out at 624 units, v's the previous 3yrs (working backwards) of 664, 565 & 687.

Does this suggest, prove, indicate anything?

tunnel

Martyn1981 wrote: »

Leccy up 158kWh v's the previous year (and best year).

Gas came out at 624 units, v's the previous 3yrs (working backwards) of 664, 565 & 687.

Does this suggest, prove, indicate anything?

Yep it does, it tells us the weather is unpredictable :rotfl:

ASavvyBuyer

As this winter has been quite a bit colder than last winter we have used about 1/3rd more gas.

Electric use, for the heat pump, has also been about 1/3rd more than last year, because of the colder outside temperatures.

Martyn1981

ASavvyBuyer wrote: »

As this winter has been quite a bit colder than last winter we have used about 1/3rd more gas.

Electric use, for the heat pump, has also been about 1/3rd more than last year, because of the colder outside temperatures.

Many thanks, as you are probably close enough for me to use as a fair comparison of this winter v's the previous one. I was hoping that after allowing for the weather the heat pump would have showed a decent impact, but didn't want to just assume.

So based on last year, and after allowing for DHW and cooking, gas consumption is down about 10%, and based on your comparison, it might be down about 30%(ish) on where it would/could have been.

I'm very happy.

PS. Also of interest, possibly, is that I can now work out my electricity consumption figures as I have an accurate export figure. So consumption for the last 6 months was:
Oct - 236
Nov - 269
Dec - 285
Jan - 281
Feb - 304
Mch - 296

I think Jan, Feb and Mch are interesting as they suggest an increased use of the heat pump when generation was higher, and the GCH could be left off, especially during the daytime.

ASavvyBuyer

Not been much discussion about this recently, despite the heatwave!
However, we are so pleased we had the heatpump/air conditioner installed.
It is working a treat keeping the house at a steady 24 degrees C, despite it being 30+ degrees C outside.
Also, it is hardly using any power to keep us cool and all coming from the Solar PV.

Dave_Fowler

We're just back from a holiday in the nice cool weather in Scotland to find the house is in the upper 30s and low 40s for most of the day - even with all the windows and doors open. Hot water fully heated, car fully charged and still lots of spare power.

What's involved in installing an air-con unit in the conservatory to cool the house in the summer and provide some heat in the autumn & spring? Is this a DIY install or do I need a specialist? How does one decide on a specification, particularly when hoping to use the PV system for most of its power supply?

Dave F

ASavvyBuyer

Dave_Fowler wrote: »

What's involved in installing an air-con unit in the conservatory to cool the house in the summer and provide some heat in the autumn & spring? Is this a DIY install or do I need a specialist? How does one decide on a specification, particularly when hoping to use the PV system for most of its power supply?

Dave F

You need an outside wall to install the external unit and a nearby electrical supply. To comply with building regs you need a certified installer. For spec, we went with the most efficient and controllable model in order to make best use of our available solar generation.

Take a look at the rest of this thread for some of the information on deciding the best model. Martyn, also had a unit installed in his conservatory, so may be able to give you more advice.