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Joule solar thermal system- west facing

  • 02-02-2020 2:01pm
    #1
    Registered Users Posts: 68 ✭✭✭ Thisonedone


    I don’t get any hot water from this apart from in summer, is that normal?


Comments

  • Registered Users Posts: 7,658 ✭✭✭ Markcheese


    Probably about right ,you'd get a bit of heat off them on a bright winter day , but it's not a huge amount...
    There's a Couple of things that might affect it though..
    Is that tubes or flat panel ?
    West facing probably not the best. .... Do you know are the panels at the right angle / is anything shading them at Anytime ?

    Slava ukraini 🇺🇦



  • Registered Users Posts: 68 ✭✭✭ Thisonedone


    Markcheese wrote: »
    Probably about right ,you'd get a bit of heat off them on a bright winter day , but it's not a huge amount...
    There's a Couple of things that might affect it though..
    Is that tubes or flat panel ?
    West facing probably not the best. .... Do you know are the panels at the right angle / is anything shading them at Anytime ?

    They are flat panels, not sure what angle but it’s a steep enough roof, there’s nothing shading them. They are about 7 years old, would cleaning them have any effect?

    That’s disappointing as I always thought solar thermal made more sense than solar electricity panels, but from reading this forum seems the opposite is the case? Or would solar electricity panels have the same problem for me given I am west facing?


  • Registered Users Posts: 7,658 ✭✭✭ Markcheese


    Ive always wondered about the economics of solar hot water .. especially when your washing machine and dishwasher usually use mains cold , a lot of showers are electric , and youre only really get the benefit 6 or 7 months a year ..
    I'd wonder about P.V. in less than optimal as well , might even depend on what part of the country ,how much cloud cover you normally have ..
    Even with pv would you need an expensive battery pack as well ?

    Slava ukraini 🇺🇦



  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,819 CMod ✭✭✭✭ unkel


    Solar thermal works well, but is expensive (even after subsidy). It only makes economic sense if you use lots of hot water. Solar PV is really cheap these days and also gets a huge subsidy. It is very inefficient to heat your water with PV, but it makes sense if you are going for a large PV setup anyway and your current way of heating water is expensive (as in you're currently heating it with an electrical immersion or with an old and inefficient gas or oil boiler)

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 68 ✭✭✭ Thisonedone


    unkel wrote: »
    Solar thermal works well, but is expensive (even after subsidy). It only makes economic sense if you use lots of hot water. Solar PV is really cheap these days and also gets a huge subsidy. It is very inefficient to heat your water with PV, but it makes sense if you are going for a large PV setup anyway and your current way of heating water is expensive (as in you're currently heating it with an electrical immersion or with an old and inefficient gas or oil boiler)

    Even in summer though it’s rare enough for us to be able to turn off the hot water schedule and rely on solar, especially last summer which had so few sunny days. The panels have never cleaned, we also had a lot of building work near us, should I look at getting them cleaned or is it simply the west facing aspect that makes the performance so poor?

    Not sure solar pv would work for us either given our west facing house and the fact we are out during the day and only back after 6.


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  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,819 CMod ✭✭✭✭ unkel


    Panels are far less efficient than tubes and you probably have only one or two panels, which will give a very limited output. Mine is a 40 tube Kingspan system, which gives very substantial hot water, even in winter on a sunny day.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 68 ✭✭✭ Thisonedone


    Wonder is it a big job to switch to tubes from panels or would it involve a ton of rewiring etc?


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,819 CMod ✭✭✭✭ unkel


    I'd leave it well alone. You already got the subsidy, you won't get it again. Concentrate on other (renewable) investments first. Like insulation your house, get a high efficiency boiler and rezone (subsidy $), solar PV (subsidy $$), or even better, an EV (subsidy $$$$)

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 68 ✭✭✭ Thisonedone


    unkel wrote: »
    I'd leave it well alone. You already got the subsidy, you won't get it again. Concentrate on other (renewable) investments first. Like insulation your house, get a high efficiency boiler and rezone (subsidy $), solar PV (subsidy $$), or even better, an EV (subsidy $$$$)

    The house was built in 2014 so it’s well insulated already and I wouldn’t be eligible for any subsidy’s. It’s just frustrating having a panel and it being fairly useless


  • Registered Users Posts: 2,092 ✭✭✭ Yellow_Fern


    Solar thermal stores energy gains a lot cheaper than PV as far as I can see


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  • Registered Users Posts: 2,092 ✭✭✭ Yellow_Fern


    unkel wrote: »
    I'd leave it well alone. You already got the subsidy, you won't get it again. Concentrate on other (renewable) investments first. Like insulation your house, get a high efficiency boiler and rezone (subsidy $), solar PV (subsidy $$), or even better, an EV (subsidy $$$$)

    He didn't say he got a subsidy
    The house was built in 2014 so it’s well insulated already and I wouldn’t be eligible for any subsidy’s. It’s just frustrating having a panel and it being fairly useless
    This is a real problem. There are probably huge numbers of freezing homes ineligible for grants as they are post 2011.


  • Registered Users Posts: 5,411 ✭✭✭ Charlie-Bravo


    I have 4 solar panels also west facing with a 300 litre cylinder. I have a ' Nutech' (company) LCD touch screen on the landing with all info, panel temp, top/bottom cylinder temp, room temp, fan system (convector radiator). Today, the roof panels are about 40 degreesC with the slight bit of sun - I have the Nutech control panel set to winter mode. The panels are not hot enough to be of benefit to heating domestic hot water cylinder. The winter mode sends the warm thermal panel liquid to the landing convector radiator. Overall it's a good system, not as good as having PV in my opinion, but that's what came with the house over 2 years ago.

    For the OP above, and to confirm what Unkel is saying, spending more money on an existing system is likely not going to yield any feasible rate of return.

    From my own point of view, and having the good thermal panel system that came with the house, I am looking into complimenting the house with PV with the remaining roof space in an E-W split. I am hoping to complete something before summer time.

    -. . ...- . .-. / --. --- -. -. .- / --. .. ...- . / -.-- --- ..- / ..- .--.



  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,819 CMod ✭✭✭✭ unkel


    astrofluff wrote: »
    Today, the roof panels are about 40 degreesC with the slight bit of sun - I have the Nutech control panel set to winter mode. The panels are not hot enough to be of benefit to heating domestic hot water cylinder.

    What makes you say that?

    The water coming into your cylinder at the bottom is typically about 10C in winter. A typical delta (difference in temp between roof panel temp and bottom of cylinder temp, before pump starts working) is 8C

    Which means that if the temp on your roof is 40C, it starts feeding the bottom of your tank with luke warm water until it reaches 32C. So from 10-32C. Which is very helpful indeed

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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