Solar iboost installation

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  • silverwhistlesilverwhistle Forumite
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    You might well do better. I've never actually checked my iboost usage display until this thread reminded me. In the 16 months since installation I've sent 1374 kwh to the immersion. I'm single and use an electric shower so my hot water usage isn't great and most of the time during the summer months I was exporting a great deal once the tank was up to temperature. For more than 6 months I haven't used any gas at all (electric cooking) and in the shoulder periods either side still got some benefit.

    This summer it was all change again as I had a wood-burner installed, and so far this winter haven't had the central heating on at all. Since the beginning of September I've used [goes and checks as I'm interested now..] 16 units or about 180 kwh of gas for hot water: I do like a hot bath occasionally after playing football!
  • nigelpmnigelpm Forumite
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    Oh dear. My expectation was better, but no experience at yet. In three of the months when I use no central heating radiators, the water and a little gas cooking uses 650 kWh of gas in each month. My hope was that the iBoost output would cover most of that. We are heavy showers in the Sterling household.

    I suspect you'll find it will cover the majority of that.
    Problem is that's only (650*0.04) = £26!
  • SterlingtimesSterlingtimes Forumite
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    nigelpm wrote: »
    I suspect you'll find it will cover the majority of that.
    Problem is that's only (650*0.04) = £26!

    Thank you, Nigel.

    Of course, you calculate for one month. If I could cover three that would be £78. And if I could cover 6 of the 12 months, that would be £156.

    Not huge, I agree. But it makes the iBoost look viable for big showers.

    The next 12 months will tell.
    Solar installed 21 November 2014 > Centre of England > 3,780 Wp > 14 *270 Watt Trina panels > 14 * Enphase micro-inverters > managed by Enlighten Envoy Hub > 19° west of south > 35° pitch > tree shading to east > iBoost > Wattson Anywhere monitoring > Schneider Electric (Drayton) MiGenie smart thermostat.
  • edited 23 December 2014 at 7:04AM
    Martyn1981Martyn1981 Forumite
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    edited 23 December 2014 at 7:04AM
    Thank you, Nigel.

    Of course, you calculate for one month. If I could cover three that would be £78. And if I could cover 6 of the 12 months, that would be £156.

    Not huge, I agree. But it makes the iBoost look viable for big showers.

    The next 12 months will tell.

    Don't forget though that collecting that much in a month would be very tricky.

    Even allowing for the gas that is used for cooking, and the lower efficiency of the boiler, and all the lost heat from the pipes (which is a loss outside of heating season), it may still be more kWh's than you generate, or more importantly have spare after domestic leccy consumption.

    I'm totally guessing here but if 50kWh's for cooking(?) then 40% losses on heating water from a gas boiler (and pipes) that leaves 360kWh (600*60%). Not impossible in a really good month, but possibly an upper figure for your calcs. It will also depend on the size of your tank and the time of day of the showers. If none during the day, then once that tank is hot, it won't be able to absorb any more leccy till some water has been drawn off.

    In 'lesser' months there will be less spare leccy to divert, and more chance of good v's poor weather days - remembering that if the boiler has done some of the work, then a following good PV day can never go back and make it up, unless you avoid showers when generation is poor. Though you can minimise the effect by experimenting with the boiler/immersion temps.

    All that aside however, your circumstances do sound like you'd make the most of it, so it would be interesting to see how much gets diverted over a year, especially now that these devices seem to be getting cheaper.

    Best of luck.

    Mart.
    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.
  • SterlingtimesSterlingtimes Forumite
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    Martyn1981 wrote: »
    Don't forget though that collecting that much in a month would be very tricky.

    Even allowing for the gas that is used for cooking, and the lower efficiency of the boiler, and all the lost heat from the pipes (which is a loss outside of heating season), it may still be more kWh's than you generate, or more importantly have spare after domestic leccy consumption.


    Thank you, Mart. Upon reflection, I think you are correct.


    I ran some figures through the Energy Saving Trusts' Water Energy Calculator with plenty of tweaking of the variables.


    water_energy.jpg


    The sinks are easily forgotten. I had to adjust to indicate a mixer shower rather than power shower since the power shower setting indicated too high a burn. Anyway, water energy usage is clearly high at Sterling Manor (-: We'll see whether iBoost delivers the required results.


    Regards, Sterling
    Solar installed 21 November 2014 > Centre of England > 3,780 Wp > 14 *270 Watt Trina panels > 14 * Enphase micro-inverters > managed by Enlighten Envoy Hub > 19° west of south > 35° pitch > tree shading to east > iBoost > Wattson Anywhere monitoring > Schneider Electric (Drayton) MiGenie smart thermostat.
  • edited 23 December 2014 at 11:10PM
    zeupaterzeupater Forumite
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    edited 23 December 2014 at 11:10PM
    Thank you, Mart. Upon reflection, I think you are correct.


    I ran some figures through the Energy Saving Trusts' Water Energy Calculator with plenty of tweaking of the variables.


    water_energy.jpg


    The sinks are easily forgotten. I had to adjust to indicate a mixer shower rather than power shower since the power shower setting indicated too high a burn. Anyway, water energy usage is clearly high at Sterling Manor (-: We'll see whether iBoost delivers the required results.


    Regards, Sterling

    6262kWh just on showers in a year ?? ... That's the equivalent of around 2Hrs under an electric shower per day(6262/9/365), so likely somewhere between 10 & 20 people having one shower each & every day ..... of course, using a DHW cylinder is different, but there's still a similar heat provision requirement.

    .... small hotel or B&B comes to mind, else there's a problem with the calculation somewhere ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • SterlingtimesSterlingtimes Forumite
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    zeupater wrote: »
    6262kWh just on showers in a year ??

    .... small hotel or B&B comes to mind, else there's a problem with the calculation somewhere ...

    HTH
    Z

    Hello zeupater. That's the figure given by the Energy Saving Trusts' calculator.

    shower.jpg

    During the months when I use no central heating base usage is 648 kWh per month (7776 kWh) per year. So the estimate seems about right.
    Solar installed 21 November 2014 > Centre of England > 3,780 Wp > 14 *270 Watt Trina panels > 14 * Enphase micro-inverters > managed by Enlighten Envoy Hub > 19° west of south > 35° pitch > tree shading to east > iBoost > Wattson Anywhere monitoring > Schneider Electric (Drayton) MiGenie smart thermostat.
  • nigelpmnigelpm Forumite
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    Thank you, Nigel.

    Of course, you calculate for one month. If I could cover three that would be £78. And if I could cover 6 of the 12 months, that would be £156.

    Not huge, I agree. But it makes the iBoost look viable for big showers.

    The next 12 months will tell.

    Sorry my mistake. You'd be extremely lucky to cover more than 1,200 Kw/h in a year i.e. 1200 *0.04 = £48.
  • edited 25 December 2014 at 8:33AM
    Martyn1981Martyn1981 Forumite
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    edited 25 December 2014 at 8:33AM
    nigelpm wrote: »
    Sorry my mistake. You'd be extremely lucky to cover more than 1,200 Kw/h in a year i.e. 1200 *0.04 = £48.

    I'd have thought that was more the lower end, rather than the lucky higher end.

    1,200kWh of gas would need about 1,000kWh of leccy (if boiler is 80% efficient), and several people over the years seem to be reporting that amount, or more. In fact Silverwhistle seems to be diverting around 1,000kWh of leccy pa despite the limitations posted.

    If losses from boiler efficiency and pipes are closer to 40% (in non heating months), then 1,000kWh of leccy is closer to 1,400kWh of gas.

    I have seen people diverting closer to 2,000kWh pa, but that was on the Navitron forum and they did have a larger thermal store. Also a poster (with regular tank) diverting around 1,200kWh of leccy from an off south, split, 3kWp system (ie less than ideal situation).

    [Edit: Merry Xmas! M.]

    Mart.
    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.
  • nigelpmnigelpm Forumite
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    I guess the question is how much of that diverted energy is useful comes into play.

    I've no doubt you could divert around 1,200 Kw/h in a good year but not useful if you only make use of 75% of it.

    Like I say might just work for people at £200 - £250 but much more and I doubt it makes economic sense.
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