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Solar Panels and Heat Pump fitted but savings not as suggested.

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Comments

  • chris_n said:
    Using electric showers when you have a heat pump or gas and storage is madness. It is just like burning £10 notes. The claims that the solar would cover most of your daytime usage is true for most people using electricity in the way that it is expected to be used. I own a property in the UK and it only imports during the day on occasional days when the weather is reallybad (today).
    Even if your panels were at full tilt you would still be importing 7kW. Maybe misunderstood rather than. misled or misheard would be the order of the day.
    It's not an electric shower, it runs off the hot water. We are as energy efficient as possible, and very careful with what we use 
  • QrizB
    QrizB Posts: 15,341 Forumite
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    It's not an electric shower, it runs off the hot water. We are as energy efficient as possible, and very careful with what we use 
    Are you certain of that?
    In your first post you said:
    The 'peaks' during the day do tend to be around shower times at around 1kwh per 5 minute shower (2 per day)
    Using 1kWh in 5 minutes suggests a load of 12kW. That's the sort of drain that is only generally seen if running an electric shower, or maybe if charging an electric car.
    What is the make and model of your shower?
    If the 12kW load isn't due to the shower, what else do you run at those times?
    N. Hampshire, he/him. Octopus Intelligent Go elec & Tracker gas / Shell (now TT) BB / Lebara mobi. Ripple Kirk Hill member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 33MWh generated, long-term average 2.6 Os.
    Not exactly back from my break, but dipping in and out of the forum.
    Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs, Best kettle!
  • QrizB said:
    It's not an electric shower, it runs off the hot water. We are as energy efficient as possible, and very careful with what we use 
    Are you certain of that?
    In your first post you said:
    The 'peaks' during the day do tend to be around shower times at around 1kwh per 5 minute shower (2 per day)
    Using 1kWh in 5 minutes suggests a load of 12kW. That's the sort of drain that is only generally seen if running an electric shower, or maybe if charging an electric car.
    What is the make and model of your shower?
    If the 12kW load isn't due to the shower, what else do you run at those times?
    It's definitely not an electric shower. It's a Mira the type that has taps and a large shower head that is plumbed directly to the hot water supply. The 1kw peaks seem to coincide with the shower times. The shower times are around 5 minutes but the usage charts are half hour blocks so im not saying we are using that amount in 5 minutes. We not running anything else at the time apart from things like the fridge that are are on permanently. I can only assume the peaks after the shower are when the water tank refills and reheats. This is what worries me, if it is using this amount of electricity to heat the hot water, how much will it be using in winter to power the heating 
  • QrizB
    QrizB Posts: 15,341 Forumite
    10,000 Posts Third Anniversary Photogenic Name Dropper
    if it is using this amount of electricity to heat the hot water, how much will it be using in winter to power the heating
    I think we need to start at the beginning.
    Before you had solar panels and a heat pump, how did you heat your home? How much energy (of each type, if it wasn't all electricity) did you typically use in a year?
    Just to give you an idea, a typical dual-fuel home might use 3000kWh of electricity and 12000kWh of gas/LPG/oil per year.

    N. Hampshire, he/him. Octopus Intelligent Go elec & Tracker gas / Shell (now TT) BB / Lebara mobi. Ripple Kirk Hill member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 33MWh generated, long-term average 2.6 Os.
    Not exactly back from my break, but dipping in and out of the forum.
    Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs, Best kettle!
  • QrizB said:
    if it is using this amount of electricity to heat the hot water, how much will it be using in winter to power the heating
    I think we need to start at the beginning.
    Before you had solar panels and a heat pump, how did you heat your home? How much energy (of each type, if it wasn't all electricity) did you typically use in a year?
    Just to give you an idea, a typical dual-fuel home might use 3000kWh of electricity and 12000kWh of gas/LPG/oil per year.

    We was on LPG for heating and hot water prior to the heat pump. Its hard to say how much we used, as we don't have a meter but I would estimate about £800 per year. Electric was 3562 kwh in the year up to having the heat pump and solar fitted 
  • Martyn1981
    Martyn1981 Posts: 15,126 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    QrizB said:
    It's not an electric shower, it runs off the hot water. We are as energy efficient as possible, and very careful with what we use 
    Are you certain of that?
    In your first post you said:
    The 'peaks' during the day do tend to be around shower times at around 1kwh per 5 minute shower (2 per day)
    Using 1kWh in 5 minutes suggests a load of 12kW. That's the sort of drain that is only generally seen if running an electric shower, or maybe if charging an electric car.
    What is the make and model of your shower?
    If the 12kW load isn't due to the shower, what else do you run at those times?
    It's definitely not an electric shower. It's a Mira the type that has taps and a large shower head that is plumbed directly to the hot water supply. The 1kw peaks seem to coincide with the shower times. The shower times are around 5 minutes but the usage charts are half hour blocks so im not saying we are using that amount in 5 minutes. We not running anything else at the time apart from things like the fridge that are are on permanently. I can only assume the peaks after the shower are when the water tank refills and reheats. This is what worries me, if it is using this amount of electricity to heat the hot water, how much will it be using in winter to power the heating 
    Hi. I think there may be some confusion here. I also assumed it must be an electric shower due to the 1kWh in 5mins reference. But now I see you say it's 1kW, which may just be the HP reheating the water (as you mention), which isn't that much, especially if only for 5-10mins (so 80Wh to 160Wh).

    Or, if it's consuming 1kWh for a shower (in total), then I don't think that's too bad either. 
    Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • ecraig
    ecraig Posts: 254 Forumite
    Part of the Furniture 100 Posts Name Dropper Combo Breaker
    edited 19 August 2023 am31 11:40AM
    You mentioned in an earlier post that you have a 3.6kWh array, so it’s clear that your array isn’t big enough to fully cover your electrical needs if you use 3.562kWh per year, let alone the heat pump.
    You need more panels. Or use less electricity.
  • QrizB
    QrizB Posts: 15,341 Forumite
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    edited 19 August 2023 pm31 12:49PM
    QrizB said:
    if it is using this amount of electricity to heat the hot water, how much will it be using in winter to power the heating
    I think we need to start at the beginning.
    Before you had solar panels and a heat pump, how did you heat your home? How much energy (of each type, if it wasn't all electricity) did you typically use in a year?
    Just to give you an idea, a typical dual-fuel home might use 3000kWh of electricity and 12000kWh of gas/LPG/oil per year.

    We was on LPG for heating and hot water prior to the heat pump. Its hard to say how much we used, as we don't have a meter but I would estimate about £800 per year. Electric was 3562 kwh in the year up to having the heat pump and solar fitted 
    In normal times, LPG is about 5p/kWh (35p/l) so £800 would be 16000kWh. (Last winter it was closer to 10p/kWh, 70p/l, so it would be useful to know what price you were paying when it worked out as £800/yr.)
    Replacing 16000kWh via a heat pump with a 3:1 SCOP will take 5300kWh, which would suggest a total annual electricity demand of about 9000kWh.
    ecraig said:
    You mentioned in an earlier post that you have a 3.6kWh array
    A 3.6kWp PV array might generate 3500kWh a year. Optimistically you might be able to use half of those; let's say 1800kWh. That leaves you to buy 7200kWh from the grid.
    I don't know what tariff you are on, but at the default SVT of 30p/kWh you could be looking at an annual electricity bill of £2200.
    The 1700kWh that you sell back to the grid could (assuming Outgoing Fixed at 15p/kWh) earn you £250 which will be a little help.
    I have made several big assumptions to get to this numbesr, as mentioned above. If you have more accurate figures it should be possible to refine this estimate further.
    N. Hampshire, he/him. Octopus Intelligent Go elec & Tracker gas / Shell (now TT) BB / Lebara mobi. Ripple Kirk Hill member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 33MWh generated, long-term average 2.6 Os.
    Not exactly back from my break, but dipping in and out of the forum.
    Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs, Best kettle!
  • QrizB said:
    QrizB said:
    if it is using this amount of electricity to heat the hot water, how much will it be using in winter to power the heating
    I think we need to start at the beginning.
    Before you had solar panels and a heat pump, how did you heat your home? How much energy (of each type, if it wasn't all electricity) did you typically use in a year?
    Just to give you an idea, a typical dual-fuel home might use 3000kWh of electricity and 12000kWh of gas/LPG/oil per year.

    We was on LPG for heating and hot water prior to the heat pump. Its hard to say how much we used, as we don't have a meter but I would estimate about £800 per year. Electric was 3562 kwh in the year up to having the heat pump and solar fitted 
    In normal times, LPG is about 5p/kWh (35p/l) so £800 would be 16000kWh. (Last winter it was closer to 10p/kWh, 70p/l, so it would be useful to know what price you were paying when it worked out as £800/yr.)
    Replacing 16000kWh via a heat pump with a 3:1 SCOP will take 5300kWh, which would suggest a total annual electricity demand of about 9000kWh.
    ecraig said:
    You mentioned in an earlier post that you have a 3.6kWh array
    A 3.6kWp PV array might generate 3500kWh a year. Optimistically you might be able to use half of those; let's say 1800kWh. That leaves you to buy 7200kWh from the grid.
    I don't know what tariff you are on, but at the default SVT of 30p/kWh you could be looking at an annual electricity bill of £2200.
    The 1700kWh that you sell back to the grid could (assuming Outgoing Fixed at 15p/kWh) earn you £250 which will be a little help.
    I have made several big assumptions to get to this numbesr, as mentioned above. If you have more accurate figures it should be possible to refine this estimate further.
    Thanks for taking the time to work those out, the last couple of bills for LPG have been £0.68/litre   not sure what that equates to in kwh. The electricity tariffs look about right.
  • QrizB
    QrizB Posts: 15,341 Forumite
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    edited 20 August 2023 am31 8:19AM
    £800-worth of LPG at 68p/l is roughly 8200kWh of heat, which will take roughly 2700kWh of electricity to replace.
    Your total electricity demand for the year will therefore be about 6300kWh, not 9000.
    Net of solar self-use, you might need to buy 4500kWh from the grid at a cost of £1350.
    Hopefully that's a bit more reasonable!
    As part of your solar PV installation you should have been fitted with a generation meter (that measures all the electricity your solar panels produce). You should also have a smart meter which will be measuring how much electricity you export. If you compare those readings you can work out how much solar electricity you have used in your house.
    Do you know where to find those numbers? Could you share them here?
    Also, have you signed up yet with an electricity supplier to pay you for your exported electricity?

    N. Hampshire, he/him. Octopus Intelligent Go elec & Tracker gas / Shell (now TT) BB / Lebara mobi. Ripple Kirk Hill member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 33MWh generated, long-term average 2.6 Os.
    Not exactly back from my break, but dipping in and out of the forum.
    Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs, Best kettle!
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