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

Martyn1981

ASavvyBuyer wrote: »

Multiplying those figure by an average of 11.1 to get kWh that equates to about 3,940kWh of gas.

Our figures for the same quarters (Jan-March) were:
2016 6,423 kWh
2017 2,804 kWh

So through those colder months, a saving of just over 56% by using the heat pump.

This month is forecast to be an even greater saving, as currently forecast to be less than 200 kWh of gas, compared to just over 900 kWh last April.

Holy Cow!!

Martyn1981

ASavvyBuyer wrote: »

Multiplying those figure by an average of 11.1 to get kWh that equates to about 3,940kWh of gas.

Our figures for the same quarters (Jan-March) were:
2016 6,423 kWh
2017 2,804 kWh

So through those colder months, a saving of just over 56% by using the heat pump.

This month is forecast to be an even greater saving, as currently forecast to be less than 200 kWh of gas, compared to just over 900 kWh last April.

OK, couldn't leave it at Holy Cow! I've gone back through your posts and found approx 124kWh of extra import. Assuming all 'extra' grid generation comes from gas at 50% efficiency, then that's 248kWh of gas burnt.

Also have to add on the gas burnt to make up for PV consumed (not exported), so I'll guess at another 124kWh of PV for HP use (?)

That's a total 496kWh of extra gas consumption (leccy generation), v's a 3,619kWh reduction in gas for GCH.

I'm staggered. :T

Martyn1981

Had quite a few opportunities to use the HP now, and works excellent, great at topping up house heat in the afternoon before a cool evening on a grey day.

But today looks like the real test. Conservatory is 16C, living room 18.5C, and 4C outside, expected to peak at 9C at midday.

Loads of sun today, and already ramping up fast at around 300W+. So, lets see if the HP can keep the living room warm, and spill enough heat to keep the rest of the house warm enough too.

Martyn1981

Well guys, you didn't lie!

Now day 4 of popping the HP on in the morning to warm things up. Today should be much warmer, but the previous 3 all started at around 2C or 3C and peaked at about 9C to 10C.

HP did a great job, boosted by solar gain from some great sunlight. No need for any GCH.

Seal of approval from the cats who moved from the bedroom to the 2 seater under the blower.

Probably got 90% of the leccy from the PV, but no doubts that even if imported it would have been better than using GCH.

Living room door open wide all the time allowing some warming of the hallway and rest of house.

Certainly a way to gain more from PV, and a (small) booster argument for batts too.

Should have done this years ago!

ajbell

Interested in this, are there grants and/or FIT payments available.
I have a 4kw solar array and could fit a heat pump in my conservatory to pump heat into my large kitchen.

ASavvyBuyer

ajbell wrote: »

Interested in this, are there grants and/or FIT payments available.
I have a 4kw solar array and could fit a heat pump in my conservatory to pump heat into my large kitchen.

Sorry, does not appear to be any grants or FIT type payments for this type of installation. Savings are on using more of the generated electric and reduction in use of GCH.

zeupater

ajbell wrote: »

Interested in this, are there grants and/or FIT payments available.
I have a 4kw solar array and could fit a heat pump in my conservatory to pump heat into my large kitchen.

Hi

As ASB mentioned, this technology isn't eligible for RHI although it's my view that it certainly should be. Domestic RHI only covers GSHP and ASHP where heat is transferred around the house on a 'wet' basis (ie similar to standard GCH with a different heat source technology), therefore air to air solutions are excluded.

there seem to be two logical reasons for this ...

.... Firstly a concern by the RHI scheme authors that including Air/Air reversible heat-pump technologies would encourage homeowners to use the units extensively for cooling in the summer, therefore increasing daytime demand and creating a new demand problem. I had a conversation with a pretty senior official at DECC a few years ago which confirmed this to be the case, however, when raising the point that there are Air/Air heating but non reversible units on the market as well as units where the cooling functionality can be locked out by the installer, further defensive argument on the point seemed to fade into a silence of uninformed embarrassment ...

.... Secondly, DECC consultations on the RHI scheme have been heavily weighted towards industry views (by 'heavily' I mean almost exclusively!). This approach certainly raises questions as to what possible reasons would lead the heat-pump manufacturing & installation sector to support technologies which typically cost the consumer between ~£8k & £20k, when Air/Air would cost far less (as little as <£1500 in many cases) and potentially offer far superior COP ratios ... so the answer to 'what possible reasons?' seems to resolve down to vested interests, it's just a shame that although providing a 'self interest' opportunity to the industry is pretty obvious to members of the public, DECC completely missed the point !


Regarding having the heat-pump in the conservatory and pumping the heat into the kitchen .... Although there's nothing wrong with the idea, the concept we're raising on this thread is to use a small but extremely efficient heat source in combination with pv to provide supplementary heating comfort to the main living area where we would normally be inactive, this mainly being in Spring & Autumn where pv generation is reasonable, but it's probably not cold enough to warrant using main heat sources (GCH etc). I believe that after much deliberation, the main reason that Martyn's decision to install is in the conservatory is one of lack of readily available alternative positions as opposed to preference.

HTH
Z

Martyn1981

zeupater wrote: »

I believe that after much deliberation, the main reason that Martyn's decision to install is in the conservatory is one of lack of readily available alternative positions as opposed to preference.

HTH
Z

Yes, I have to back that point up. In my case 'the conservatory' is an overly glamorous claim for what is actually a small room with one glass side approx 2.4m by 2.1m (UPVC doors and windows), and a DG glass roof of approx 2.4m by 2.7m. The other 3 sides are internal walls (one a party wall).

We've now had blinds installed that cover all glass, and are honeycomb type blinds with a ~10mm hollow in them, and a white reflective outer. I'm hoping that these will minimise heat loss when heating, and minimise heat gain when cooling. It's also ESE facing which is extremely important for cooling as it will lose solar gain from about 2pm onwards, at that point switching on the aircon means fighting ambient, not the vastly greater solar gain.

If someone has a large conservatory with glass to 3 sides and south facing, then whilst an ASHP may be a good choice for heating/cooling that room, it may not be a good way to follow the lead set by Z & ASB on here, as a lot of energy will be spent fighting with nature. So whilst I believe that my situation is environmental, this may not fit for all conservatories.

I hope to see a decent reduction in gas consumption over a year, but doubt it will match (percentage wise) what ASB has been reporting.

ASavvyBuyer

April 2017 update for using the Toshiba Air Conditioner/Heat Pump.

Comparing Gas & Electric use from April last year have ended up with the following figures:
Gas use down to 177kWh compared to 904kWh last year (a saving of just over 80%) :j
Electric import down by 7 kWh (probably due to slightly better generation than last year at the beginning of the month)
Rough estimate of % of solar PV generated electricty used has increased from under 40% to over 50% :j
From checking the historical records at Accuweather.com for weather, it has been very similar to last year, temperature wise, except that the beginning of the month was slightly warmer and sunnier; and the end of the month slightly cooler and duller. :cool:

Martyn1981

Hiya ASB, tricky to make comparisons here, but no GCH at all in April, with the ASHP probably running for 100+hrs, but total import was only 96kWh (82 in 2016 and 97 in 2015).

Gas consumption was 13 units in April (around 150kWhs) but can't draw any conclusions yet, as I don't have monthly figures to compare. The last few years have been 42-94 units for 2nd quarter, and most/all GCH consumption would presumably be in April, but doubt I'll be able to draw anything meaningful from the end of qtr data, except I hope it will be less this year.

Looking forward to qtr 4 when I expect to see some results, especially if it's mild, and the ASHP can be left to do its thing.