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  • FIRST POST
    • zeupater
    • By zeupater 21st Jul 13, 5:35 PM
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    zeupater
    Discussion ... ASHP(Air/Air) with Solar pv ....
    • #1
    • 21st Jul 13, 5:35 PM
    Discussion ... ASHP(Air/Air) with Solar pv .... 21st Jul 13 at 5:35 PM
    Hi All

    The combination of a small ASHP(Air/Air) with Solar pv seems to be a valid pairing of complementary technologies which has been raised a number of times on this forum.

    The idea of this thread is to encourage discussion of this combination in order to validate what an appropriate equipment specification would look like in order to maximise performance benefits in a typical domestic environment.

    Obviously, it is well understood that a typical domestic-scale solar pv system will not generate sufficient energy to provide winter heating, but should be considered as being a 'shoulder' months supplementary heat source for well insulated properties ... it is therefore best to concentrate on Spring & Autumn as being the target periods for heat provision, with an additional benefit of provision of cooling in heat-wave conditions such as we've been experiencing recently.

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
Page 10
    • zeupater
    • By zeupater 29th Nov 17, 10:52 PM
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    zeupater
    Notice that GCH has come on a few times this month, either in the morning or evening to warm the bedroom up when the wireless programmable thermostat has called for heat.

    However, with the heat pump running in the lounge and the internal door opens to circulate the warm air, our gas use is down to a less than a third of what it was last October, at a predicted less than 200kWh for the month and electric use only up by about 20kWh, despite the recent poor PV generation.

    From checking stats for October last year, it has been a bit milder so far this year, but by only a couple of degrees, but there has not been much sun
    Originally posted by ASavvyBuyer
    Hi

    Bad News ... It's been dull again today so very little solar gain (again)
    ...
    Better News ... It's just about 3weeks until the shortest day
    ...
    Even Better News ... The log-burner was fired-up for a while today, not bad for the first burn ... almost December & only fed for a handful of hours thanks to the ASHP's contribution .. might need to use the GCH if the promised cold spell is actually cold .. & long!
    ...
    Outstanding News ... solar thermal has only needed the occasional GCH top-up and according to the weatherman it's going to be sunny tomorrow ..
    ...
    And back to the Bad News ... the DHW storage is pretty much depleted so even a really sunny day wouldn't make much difference, so another top-up is due either tomorrow or Friday ... couple this with the recent accuracy of the weather forecast & I'll not be getting too excited either way! ... ...

    Good things these high efficiency ASHPs ... if you can keep the small amount of heat they produce in it's surprising how much they actually help-out ....

    HTH
    Z
    Last edited by zeupater; 29-11-2017 at 10:55 PM.
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Martyn1981
    • By Martyn1981 30th Nov 17, 8:02 AM
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    Martyn1981
    Good things these high efficiency ASHPs ... if you can keep the small amount of heat they produce in it's surprising how much they actually help-out ....

    HTH
    Z
    Originally posted by zeupater
    Mine's been running pretty much every day from about 9am to 3pm, apart from one day when I generated almost zero, but no heating was needed (grey and warm).

    Dawned on me yesterday that at a COP of 4, just the GCH pump wattage run through the ASHP comes out close to my oil filled rad at 400W, which was good for keeping the chill off. Though I'm going to be below a COP of 4 these days I suspect.

    Tonight I'll see how this months leccy import compares to previous years.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Martyn1981
    • By Martyn1981 1st Dec 17, 7:54 AM
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    Martyn1981
    Tonight I'll see how this months leccy import compares to previous years.
    Originally posted by Martyn1981
    Leccy import was 189kWh, bit higher due to heat pump, with previous years 160-180, and total household consumption was 269kWh.

    I don't have monthly gas figures, and hard to compare due to annual weather differences, but I suspect this quarter could be 500kWh to 1,000kWh lower, but will have to see in a month.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 12th Dec 17, 10:44 AM
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    zeupater
    Hi

    Minus silly temperatures here last night, 10.5" of snow on the log store, bright sunshine all day yesterday and similar so far this morning although the sky's quite hazy ... heating went on for a couple of hours again yesterday to increase the background temperature, apart from that the heat-pump is performing really well, despite the fins currently being heavily encrusted with frost! ....

    Keep warm ...
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • SalsaDanca
    • By SalsaDanca 17th Dec 17, 12:07 PM
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    SalsaDanca
    Hi Zeupater,

    My house has central heating with an oil-fired boiler, and an air-source heat pump. How do you decide when to use one heating system instead of the other? Do you use the heat pump whenever possible, and only turn on the central heating when the heat pump isn't enough?

    I have a monitoring system that shows me how much electricity my house is using vs solar generation, so I can see how much the heat pump is costing me when there's not enough solar power. I'm sure the boiler is more expensive to use, but it looks cheaper because I can't see how much oil it's using.
    • zeupater
    • By zeupater 17th Dec 17, 4:34 PM
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    zeupater
    Hi Zeupater,

    My house has central heating with an oil-fired boiler, and an air-source heat pump. How do you decide when to use one heating system instead of the other? Do you use the heat pump whenever possible, and only turn on the central heating when the heat pump isn't enough?

    I have a monitoring system that shows me how much electricity my house is using vs solar generation, so I can see how much the heat pump is costing me when there's not enough solar power. I'm sure the boiler is more expensive to use, but it looks cheaper because I can't see how much oil it's using.
    Originally posted by SalsaDanca
    Hi

    Sounds like you have a true bivalent system where the heat-pump and the oil boiler both feed the radiators, maybe with auto-selection of heat-source depending on outside temperature?

    The small air-to-air heat-pump we use is fully independent of other heat sources - it has multi set point/day 7 day thermostatic timer, but it's mainly used on 'manual' as you would an electric or gas fire in the main living area, before opening internal doors to allow heat to balance around the house overnight, and of course, we look to utilise the unit when the solar pv is generating

    When the ambient temperature causes the house to cool we progressively use the log-burner then the GCH to top the heat up, however, the combination of masses of insulation & high internal thermal mass means that as long as we don't allow the structure to cool the temperature tends to stay reasonably constant .... it's very rare that we need to use all three heat-sources, but through setting the thermostats at different points everything works well, the log burner normally having the last say! ...

    Similar to you, we constantly monitor (real-time) electricity generation and have the advantage if having metered gas consumption although oil heating systems can easily have in-line flow-meters installed to provide similar consumption information .... having calculated the relative heating costs, the comfort & cost priority for us is heat-pump, log-burner then GCH ...

    HTH
    Z
    Last edited by zeupater; 17-12-2017 at 4:41 PM. Reason: +the
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • SalsaDanca
    • By SalsaDanca 19th Dec 17, 10:28 AM
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    SalsaDanca
    Hi,

    Thanks for the detailed reply. My system isn't bivalent, the radiators are only heated by the boiler. The heat pump runs two air conditioning units in the lounge, and one on the upstairs landing. There's also a wood burning stove in the lounge, so I have quite a few options for heating. An Immersun diverter provides hot water from surplus solar power for most of the year.

    The air con units have simple on/off timers, but so far I've been using them in manual mode. I've experimented with a Tado controller for one of the units, which should control the air conditioning using a mobile phone app, but it doesn't work as well as I'd hoped.
    • ASavvyBuyer
    • By ASavvyBuyer 30th Dec 17, 7:11 PM
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    ASavvyBuyer
    Heat Pump has been a real bonus over the last few days.
    There was a fault on next doors mains power cable that ended up with us being on a generator for a couple of days, set up by Western Power.
    For some strange reason it stopped our GCH from working, but the Solar PV & heat pump carried on working a treat.
    Back on normal mains now & GCH working OK again; but still more efficient to use the heat pump as main source of warmth in the lounge.
    Rhondda Cynon Taf, 4kWp, W roof, 30 pitch, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • Martyn1981
    • By Martyn1981 8th Feb 18, 7:31 AM
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    Martyn1981
    ASHP's rock!

    Been a star in Dec and Jan, but Feb is staggering - most days it's been going like a train, so no need for daytime GCH.

    Small benefit of having it in the conservatory is that I can set the heat higher. With the living room ajar (for cats) it's about one degree less than the conservatory, but with the door wide open it's around 4/5 degrees less, so conservatory at 25C, with heat leaking through open window to kitchen, and living room at almost 20C with hallway warm too.

    So low gen days, just warm living room, high gen days I pump it up!

    Leccy use hard to say, but comparing Jan 18 to lowest previous Jan is +30kWh's, so 200kWh's for a year (6 months) seems a fair to high guess.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Martyn1981
    • By Martyn1981 8th Feb 18, 7:38 AM
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    Martyn1981
    New plan, perhaps 2020-22.

    Add 4 panels in the garden (1.2 to 1.5kWp) south facing 60d pitch.
    Add a big batt such as the PWII.
    Get an EV.
    Get E7.

    Should be able to cover house and EV use from Apr to Sept with zero or negligible import.

    Mch & Oct, all leccy including ASHP covered by PV and batt, with EV on E7.

    Nov - Feb, EV on E7 and batt topped up by E7 to supplement PV.

    So, possibly, zero daytime import all year, even with EV use and ASHP supplementing heating.

    I think?
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • ASavvyBuyer
    • By ASavvyBuyer 8th Feb 18, 10:31 AM
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    ASavvyBuyer
    New plan, perhaps 2020-22.

    Add 4 panels in the garden (1.2 to 1.5kWp) south facing 60d pitch.
    Add a big batt such as the PWII.
    Originally posted by Martyn1981
    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?
    Rhondda Cynon Taf, 4kWp, W roof, 30 pitch, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • Martyn1981
    • By Martyn1981 8th Feb 18, 10:48 AM
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    Martyn1981
    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?
    Originally posted by ASavvyBuyer
    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.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Martyn1981
    • By Martyn1981 20th Feb 18, 8:08 AM
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    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.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 20th Feb 18, 2:14 PM
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    zeupater
    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.
    Originally posted by Martyn1981
    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 ....

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

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • ASavvyBuyer
    • By ASavvyBuyer 20th Feb 18, 6:58 PM
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    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.
    Rhondda Cynon Taf, 4kWp, W roof, 30 pitch, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • Coastalwatch
    • By Coastalwatch 23rd Feb 18, 3:08 PM
    • 84 Posts
    • 182 Thanks
    Coastalwatch
    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.
    Originally posted by Martyn1981
    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
    • By Martyn1981 23rd Feb 18, 3:27 PM
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    Martyn1981
    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?
    Originally posted by Coastalwatch
    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.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 23rd Feb 18, 3:46 PM
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    • 5,387 Thanks
    zeupater
    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? .
    Originally posted by Coastalwatch
    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
    Last edited by zeupater; 23-02-2018 at 4:30 PM. Reason: grammar
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • zeupater
    • By zeupater 23rd Feb 18, 4:26 PM
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    • 5,387 Thanks
    zeupater
    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!
    Originally posted by zeupater
    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! ....

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Martyn1981
    • By Martyn1981 23rd Feb 18, 7:00 PM
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    • 11,301 Thanks
    Martyn1981
    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! ....

    HTH
    Z
    Originally posted by zeupater
    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.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
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