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Renewables: "talking 'bout my generation"

edited 19 December 2019 at 11:25PM in Green & ethical MoneySaving
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  • Kernel_SandersKernel_Sanders Forumite
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    Same curtailment of peak output as per yesterday, but another ½kWh added to yesterday's record nontheless; now 21.88 kWh. Had immersion on again, but thermostat cut in when bottom of cylinder barely warm. Why is this when it is turned to its maximum of 180°F?
  • EricMearsEricMears Forumite
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    Same curtailment of peak output as per yesterday, but another ½kWh added to yesterday's record nontheless; now 21.88 kWh. Had immersion on again, but thermostat cut in when bottom of cylinder barely warm. Why is this when it is turned to its maximum of 180°F?

    As usual I'm just a bit behind you (20.77) - almost certainly due to shallower pitch as I didn't see a cloud all day apart from a few contrails.

    Immersion heater is probably in top half of tank ? They're designed that way to give a quick boost to DHW so you can do a bowlful of washing up or have a (short) shower asap. Very little circulation in a DHW cylinder so water at stop gets hot and bottom stays cold. Doesn't matter quite so much with the coil you probably have heated by a gas boiler or whatever as (a) that's usually set a bit lower and (b) it's controlled by a tank thermostat which is also set lower in tank.

    You could try fitting another (pref low power) element at bottom of tank but doubtful whether cost would be justified.
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    BEV : Nissan Leaf e+
  • edited 28 March 2012 at 12:57AM
    Kernel_SandersKernel_Sanders Forumite
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    edited 28 March 2012 at 12:57AM
    EricMears wrote: »
    As usual I'm just a bit behind you (20.77) - almost certainly due to shallower pitch as I didn't see a cloud all day apart from a few contrails.
    Yes, same here. I still think you will catch up (and, indeed, overtake me) before we reach the solstice.
    EricMears wrote: »
    Immersion heater is probably in top half of tank ? Very little circulation in a DHW cylinder so water at stop gets hot and bottom stays cold. Doesn't matter quite so much with the coil you probably have heated by a gas boiler or whatever as (a) that's usually set a bit lower and (b) it's controlled by a tank thermostat which is also set lower in tank.
    Aren't all single element immersion elements at the top of the cylinder? I just want to get all the water as hot as possible so it will cover the next couple of cloudy days that we have. Is it possible to disable the thermostat? I remember about 25 years ago the water boiling in my cylinder with steam coming from the header tank! Can't remember if this was due to the element or the thermostat for the gas coil that you mentioned.
    EricMears wrote: »
    You could try fitting another (pref low power) element at bottom of tank but doubtful whether cost would be justified.

    They're designed that way to give a quick boost to DHW so you can do a bowlful of washing up or have a (short) shower asap.
    The cylinder's quite old (possibly 35 years), so may invest in a stainless steel one. I'd want a small (500W?) element at the top so I can still have free hot water and that short shower in the winter.
  • edited 28 March 2012 at 10:17AM
    EricMearsEricMears Forumite
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    edited 28 March 2012 at 10:17AM
    Yes, same here. I still think you will catch up (and, indeed, overtake me) before we reach the solstice..

    The optimum pitch for SS day would be approx 30deg (latitude - 23deg). Your 23deg is closer to that than my 17.5 - but we'll both be better off that day than anyone with a slope of 45deg.
    Aren't all single element immersion elements at the top of the cylinder? I just want to get all the water as hot as possible so it will cover the next couple of cloudy days that we have. Is it possible to disable the thermostat? I remember about 25 years ago the water boiling in my cylinder with steam coming from the header tank! Can't remember if this was due to the element or the thermostat for the gas coil that you mentioned.

    The cylinder's quite old (possibly 35 years), so may invest in a stainless steel one. I'd want a small (500W?) element at the top so I can still have free hot water and that short shower in the winter.

    Nothing easier than disabling a thermostat - just bridge it with a bit of wire. HOWEVER, nothing more dangerous than an exploding DHW cylinder ! I wouldn't risk it. You can certainly buy replacement thermostats and with a bit of hunting around you should find one with a higher setpoint than normal. My 'Heatbank' has two adjustable thermostats in series - one goes to 80, the other 90 deg C; may sound silly but I guess the idea is that if you choose to short out the 80 and rely on the 90 the manufacturer hasn't recommended that.

    If you're buying a new cylinder, I'd suggest you specify one with two (or even more) immersion heater mounting points. One high wattage one in normal place to give almost instant emergency DHW and a couple of smaller ones at bottom so that you can wire up one (or both - depending on surplus level) to 'waste' spare electricity. Additional cost over a standard cylinder would be modest but whole cost of an unnecessary replacement probably not justified (although copper scrap value might help pay for a SS tank ?) .

    I'll try & look up a contact for purpose built cylinders from the UK_selfbuild forum.

    http://www.newarkcoppercylinder.co.uk
    They are pretty handy for Mansfield but only seem to do copper ones.

    I've PM'd you with some more
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    BEV : Nissan Leaf e+
  • EricMearsEricMears Forumite
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    Kernel S :

    I have sent you three PMs today.

    However, looking at my 'MSE control panel' it says I haven't sent any !

    Please let me know if you received them. If not , perhaps you'd care to try and PM me with an email address and I'll reply with info about other tank manufacturers and hi-temp imm heater thermostats.

    Regards
    Eric
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    BEV : Nissan Leaf e+
  • edited 28 March 2012 at 10:38PM
    Kernel_SandersKernel_Sanders Forumite
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    edited 28 March 2012 at 10:38PM
    Thanks Eric, I've received all 3 plus the test PM. There's something wrong with the system, as I had a PM missing from my sent box a fortnight ago, but it was received. Won't have time to look at those links just now as I'm searching for docs in support of my 2006-07 tax refund (deadline 31 March!)
    20.02kWh today, nearly 1½kWh down on yesterday. Peak down to about 2870W; not sure why in a cloudless sky! I was peaking at around 3500 a fortnight ago.
  • EricMearsEricMears Forumite
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    20.02kWh today, nearly 1½kWh down on yesterday. Peak down to about 2870kW; not sure why in a cloudless sky! I was peaking at around 3500 a fortnight ago.


    Funnily enough, ours was also slightly (1.2kw) down on yesterday. Peak 2.76kw at 12:40 (almost half an hour before true noon) with a distinct 'nibble' out of the otherwise smooth curve.

    High level haze ? Maybe even panels getting a bit warmer ?
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    BEV : Nissan Leaf e+
  • We exceeded 125% of our PVGIS estimate by 11am Weds, just before we set off for a few days away. Fortunately my Solo PV is logging away while we soak up the sun's rays elsewhere. If we've made another 55kWh then that'll be 1000kWh clocked up in total. Happy (sunny) Days!
    Cider Country Solar PV generator: 3.7kWp Enfinity system on unshaded SE (-36deg azimuth) & 45deg roof
  • KevinGKevinG Forumite
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    Wow. What a week! 76.17kWh in 7 days (2kWp system), exceeded 10kWh every day, completely smashed any period in the whole of last summer and now exceeded March PVGIS by 53%. :j
    Baxi Ecogen 24/1.0 Micro-CHP boiler installed Oct-2010; 2kWp Solar PV - 10*200W Kioto, SMA Sunny Boy 2000HF, SSE facing, some shading in winter, 37° pitch, installed Jun-2011, inverter replaced Sep-2017 AND Feb-2022.
  • KevinGKevinG Forumite
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    What a difference a (cloudy) day makes. Only 2.5kWh today. So that's March over, it would be great to have an April like last year's (before I had the panels) but with some overnight rain to ease the drought :)
    Baxi Ecogen 24/1.0 Micro-CHP boiler installed Oct-2010; 2kWp Solar PV - 10*200W Kioto, SMA Sunny Boy 2000HF, SSE facing, some shading in winter, 37° pitch, installed Jun-2011, inverter replaced Sep-2017 AND Feb-2022.
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