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

Martyn1981

ASavvyBuyer wrote: »

If you add some more panels & a battery how will that affect your FIT & Export payments?

It is something I would like to do, maybe add some panels to our east facing roof with a battery to benefit from the 5% VAT rate, but even though we would generate more, if we added 100% more panels would the amount we generate be halved when working out the FIT payments?

I'm thinking of it as a package because,

- I've worn Wifey down to allowing some steep panels against the garden fence, yippee.

- the VAT savings on a batt make it sensible.

- I believe the ESE Solaredge inverter can take the extra panels, so no inverter, or internal wiring costs.

- I think I can build a simple frame myself by driving two scaffolding poles into the ground (vertical and 60d pitch) then another 3m further down. So install costs will be minimal - attach two frame rails, attach panels, run cable.

- Regarding FiT's, the extension won't get any nor export. I'll have to tell my FiT provider and they'll apportion generation. So if I add 1.2kWp to the 3.58kWp, then they'll pay me FiT's and export on 3.58/4.78ths of generation.

I think it makes sense if I can do it cheap, if it saves VAT on batt, and provides generation in the winter and midday Nov-Jan when my panels can't see much sun.

Still in the mental planning stage, but if my assumptions are right, I think it's a sensible package.

Also, whilst not worth the pain and distress (especially to family and friends), I might manage most of this, even a secondhand EV, from monies that literally 'fell off the back of a lorry' so to speak.

Martyn1981

Nice leap today. The sun rises behind a house to the East, and pops out to the SE above their roof. But today the sun was just high enough to scrape over their roof, so it suddenly rose in the ESE (almost east) for the first time (as far as my panels are concerned).

Generation exceeded heat pump consumption at 7.59am. :cool:

zeupater

Martyn1981 wrote: »

Nice leap today. The sun rises behind a house to the East, and pops out to the SE above their roof. But today the sun was just high enough to scrape over their roof, so it suddenly rose in the ESE (almost east) for the first time (as far as my panels are concerned).

Generation exceeded heat pump consumption at 7.59am. :cool:

Hi

With a westerly array we're gaining at the opposite end of the day, but I must admit to having run the heat pump quite a lot recently even when we're not generating ....

22.3°C in here at the moment, solar is pushing around 4.5kW.t into the house & we're currently exporting over 2kW to the grid! ... :cool:

HTH
Z

ASavvyBuyer

Had the heat pump on all day today, some power diverted to the hot water tank, two loads of washing & used the dishwasher and still exporting at times.

Coastalwatch

Martyn1981 wrote: »

Nice leap today. The sun rises behind a house to the East, and pops out to the SE above their roof. But today the sun was just high enough to scrape over their roof, so it suddenly rose in the ESE (almost east) for the first time (as far as my panels are concerned).

Generation exceeded heat pump consumption at 7.59am. :cool:

It's encouraging seeing the ASHP system delivering via SP even in the darkest months. It's something I'm interested in pursuing but have no idea what output panels give in the winter months or over what duration. With our roof facing SSE I'm wondering if there will be sufficient SP energy to drive the ASHP in the afternoon. The only addition I could sensibly make would be a single panel horizontally mounted in the vertical plane on the WSW gable end. Given panels only produce 295w max I've no idea what additional output this single panel might give with a low winter sun in late afternoon. Another 100watts or so might just be enough of an addition to drive the ASHP for another hour or so but suspect the diminishing return from the 20 on the SSE roof are hardly likely to be compenstaed for? Does anyone have a panel/s similarly mounted who could furnish me with actual output figures from their system please?




.

Martyn1981

Coastalwatch wrote: »

It's encouraging seeing the ASHP system delivering via SP even in the darkest months. It's something I'm interested in pursuing but have no idea what output panels give in the winter months or over what duration. With our roof facing SSE I'm wondering if there will be sufficient SP energy to drive the ASHP in the afternoon. The only addition I could sensibly make would be a single panel horizontally mounted in the vertical plane on the WSW gable end. Given panels only produce 295w max I've no idea what additional output this single panel might give with a low winter sun in late afternoon. Another 100watts or so might just be enough of an addition to drive the ASHP for another hour or so but suspect the diminishing return from the 20 on the SSE roof are hardly likely to be compenstaed for? Does anyone have a panel/s similarly mounted who could furnish me with actual output figures from their system please?

Hiya, for a purely comparative exercise, try PVGIS, pop in your details and rough system size, and scribble down the Oct, Nov, Dec, Jan, Feb & Mch monthly generation figures.

Then pop in 5kWp at -70 azimuth and 30d pitch to see what my system would do (I've said 5kWp to estimate the sum of my systems, as the WNW will be poorer).

This wouldn't be scientific, but should give you a rough ratio.

So for instance, if your set up was 1.25 times the generation of my set up, then you could probably expect about 1.25 times the power at any given time.

If I'm happy Oct, Nov, late Jan, Feb & Mch, then you should be happier, and possibly Dec and early Jan too.

Warning, I might be talking carp here, as something doesn't sound quite right, but it's all fun learning I suppose.

zeupater

Coastalwatch wrote: »

It's encouraging seeing the ASHP system delivering via SP even in the darkest months. It's something I'm interested in pursuing but have no idea what output panels give in the winter months or over what duration. With our roof facing SSE I'm wondering if there will be sufficient SP energy to drive the ASHP in the afternoon. The only addition I could sensibly make would be a single panel horizontally mounted in the vertical plane on the WSW gable end. Given panels only produce 295w max I've no idea what additional output this single panel might give with a low winter sun in late afternoon. Another 100watts or so might just be enough of an addition to drive the ASHP for another hour or so but suspect the diminishing return from the 20 on the SSE roof are hardly likely to be compenstaed for? Does anyone have a panel/s similarly mounted who could furnish me with actual output figures from their system please? .

Hi

In addition to Mart's post above, have a look at UK systems on the PVOutput site .. <link> .. or at this brief analysis on seasonal variability on the Vriconian site.

We're currently generating 2.2kW, getting ~3.5kW of heat, powering everything that's on in the house and still exporting well over 50% ... that's in February, but it is a rare sunny day!

Our heat-pump has been running since around 9:30, on low for one room at first, but after the sun moved onto the panels the doors have been opened-up ... we don't usually use the HP on high power like this, but wanted to put some heat into the thermal mass but didn't want to use the log-burner today!

HTH
Z

zeupater

zeupater wrote: »

Our heat-pump has been running since around 9:30, on low for one room at first, but after the sun moved onto the panels the doors have been opened-up ... we don't usually use the HP on high power like this, but wanted to put some heat into the thermal mass but didn't want to use the log-burner today!

Hi All

Brrrr to Mmmmm... it's not particularly cold in the house, but not as warm as it usually is where I'm sitting, so with the doors open my toes were starting to feel a little icy .... shut the internal doors a few minutes ago to raise the temperature in here before the sun disappears and the temperature is rocketing up .... Mmmmm, that's more like it, house warmer, toes thawing and with generation of over 3kWh/kWp so far today (best this year!) not a penny being spent! .... :cool:

HTH
Z

Martyn1981

zeupater wrote: »

Hi All

Brrrr to Mmmmm... it's not particularly cold in the house, but not as warm as it usually is where I'm sitting, so with the doors open my toes were starting to feel a little icy .... shut the internal doors a few minutes ago to raise the temperature in here before the sun disappears and the temperature is rocketing up .... Mmmmm, that's more like it, house warmer, toes thawing and with generation of over 3kWh/kWp so far today (best this year!) not a penny being spent! .... :cool:

HTH
Z

Incredible day here. GCH was on from 6.30am to 8am. ASHP went on at 8am, and we were exporting by 8.30am (small import before that). Outside temp was 2C.

I was running it at 25C, living room 20-21C with door wide open to hallway.

Turned it down to 19C whilst dishwasher was on, then back up to 25C (but conservatory was still 22C+ anyway).

Probably importing a bit by 4.30pm (WNW was generating about 400W) when switched off.

Conservatory door closed at 5.30pm when room temps equalised.

The combination of cold with strong sunshine was a perfect example of when I'm getting the most benefit out of this.

Coastalwatch

Martyn1981 wrote: »

Hiya, for a purely comparative exercise, try PVGIS, pop in your details and rough system size, and scribble down the Oct, Nov, Dec, Jan, Feb & Mch monthly generation figures.

Then pop in 5kWp at -70 azimuth and 30d pitch to see what my system would do (I've said 5kWp to estimate the sum of my systems, as the WNW will be poorer).

This wouldn't be scientific, but should give you a rough ratio.

So for instance, if your set up was 1.25 times the generation of my set up, then you could probably expect about 1.25 times the power at any given time.

If I'm happy Oct, Nov, late Jan, Feb & Mch, then you should be happier, and possibly Dec and early Jan too.

Warning, I might be talking carp here, as something doesn't sound quite right, but it's all fun learning I suppose.

Thanks for the helpful (Fishy!edit) suggestion Martyn, I've just completed the exercise with the following results. I also added a third row for the single panel only on the WSW wall. Wasn't sure if PGVIS would return figures, but surprisingly it did!

........... 5Kw70Is 30p..........5.7kw -20Is 22p..........0.3kw +70Is 90p
Oct ...................233........................341......................11
Nov...................131........................197........................6.5
Dec....................91.........................136........................4.5
Jan....................105........................157.........................5
Feb...................170.........................235........................7.5
Mar...................357........................459......................14

I used Cardiff for your location, you're a half a degree further south than us. The 20 panel array I have in mind at 5.7w appears to return a higher output, circa 50% in Dec and Jan which is indeed encouraging. Not sure what to make of the single panel figures, but if we take there to be sunshine only every other day at this time of year, say 15/month that might suggest 300watts/day in Jan/Dec and half as much again in Feb/Nov. Given that the panel wouldn't attract any sunshine until mid day and it's then dark around four o'clock then perhaps 75 or 110watts/hour!
I looked at potential savings from the GCH system for the mid eight months of the year only if we used ASHP for heating from PV instead. Given that we use approx 100kwh gas/month for hot water only, then savings based on last years consumption would total around £60(2122kwh).
Presumably a sunny position for siting the outside ASHP unit is preferred in winter to attract some warmth! However, our ideal position for it would be up on the ENE gable end above the flat roof of the garage, tucked nicely out of site for us and near neighbours. So not the warmest spot!
I suppose the consolation being that in the summer when aircon might be required it will probably be in the shade by noon!

Yep! Fun learning, but was school ever this interesting. If only I could remember!