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Solar Water Heating System

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  • 23-11-2015 8:27pm
    #1
    William F
    Closed Accounts Posts: 473 ✭✭


    I've a cottage in the west of Ireland that's dormant for almost 50 weeks of the year. I want to install a heating system in it to stop it from falling into dilapidation. At the moment it only has open fires and a hot water boiler.

    I was thinking of installing a Solar Water Heating System so as to have the hot water circulating around the radiators all year round.

    What kind of money am I likely to pay for installation of a system like this and will it work?


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    #2
    murphaph
    Registered Users Posts: 19,018 ✭✭✭✭murphaph


    OT but possibly important: Is the building properly insured for such vacant periods?


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    #3
    MicktheMan
    Registered Users Posts: 2,825 ✭✭✭MicktheMan


    William F wrote: »
    and will it work?

    No


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    #4
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,140 Mod ✭✭✭✭BryanF


    I'd probably install Pv and use it to run an electric heat source

    More tech but less leaks.


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    #5
    William F
    Closed Accounts Posts: 473 ✭✭William F


    BryanF wrote: »
    I'd probably install Pv and use it to run an electric heat source

    More tech but less leaks.

    What's pv?


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    #6
    johnnyc
    Registered Users Posts: 618 ✭✭✭johnnyc


    A photovoltaic system, also solar PV power system, or PV system, is a power system designed to supply usable solar power by means of photovoltaics.


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    #7
    dathi
    Registered Users Posts: 1,386 ✭✭✭dathi


    johnnyc wrote: »
    A photovoltaic system, also solar PV power system, or PV system, is a power system designed to supply usable solar power by means of photovoltaics.

    you said everything except what it does:rolleyes: it generates electricity from solar


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    #8
    quentingargan
    Registered Users Posts: 1,627 ✭✭✭quentingargan


    There are specialist devices to divert your surplus electricity to the immersion, so your PV can give you solar water heating. A 2kw system would cost about €3K plus VAT for the hardware - not much more than solar thermal, but a lot easier to retrofit and as Bryan said, no leaks or moving parts.

    But be careful about the diversion device. Some use triacs to switch like a crude dimmer switch. They distort the grid, not just in your house, but hundreds of yards down the road as well.

    Make sure the unit is high frequency switching and not based on phase angle / triac switching.


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    #9
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    Isnt there some cost in connecting to the grid in this way? couldnt it be possible to connect a solar PV system to an air sourced heat pump and an immersion if its sized correctly?
    Would this need any specialist equipment? maybe some contactors but nothing of the cost of a device that has to match the grids frequency and be capable of switching off in the event of failures on the grid.


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    #10
    quentingargan
    Registered Users Posts: 1,627 ✭✭✭quentingargan


    cerastes wrote: »
    Isnt there some cost in connecting to the grid in this way? couldnt it be possible to connect a solar PV system to an air sourced heat pump and an immersion if its sized correctly?
    Would this need any specialist equipment? maybe some contactors but nothing of the cost of a device that has to match the grids frequency and be capable of switching off in the event of failures on the grid.

    You can't run a heat pump stably without a grid. You could use a battery system to provide a stable grid, and charge the battery from solar, but this is all getting more and more expensive.

    The system of diverting to an immersion stands up price-wise against solar thermal and is maintenance free, but it would be better to export your surplus to the grid and get paid for it...


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    #11
    nice_guy80
    Closed Accounts Posts: 8,723 ✭✭✭nice_guy80


    quentingargan wrote: »
    You can't run a heat pump stably without a grid. You could use a battery system to provide a stable grid, and charge the battery from solar, but this is all getting more and more expensive.

    The system of diverting to an immersion stands up price-wise against solar thermal and is maintenance free, but it would be better to export your surplus to the grid and get paid for it...

    except you cannot do that now


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    #12
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    quentingargan wrote: »
    You can't run a heat pump stably without a grid. You could use a battery system to provide a stable grid, and charge the battery from solar, but this is all getting more and more expensive.

    The system of diverting to an immersion stands up price-wise against solar thermal and is maintenance free, but it would be better to export your surplus to the grid and get paid for it...

    I suppose a battery could be costed into things,
    But I dont know if that would not make it viable then or so less viable that its not worth it due to less predictable circumstances, like if a battery fails.
    Regarding batteries Id wondered would this affect a standard domestic scenario or could they even be put in a house? insurance? Maybe if you had a garage but that might mean extending wiring down from a solar PV panel/grid and then back where you need it. Id still probably want them in some kind of ceramic container and I wonder if you'd have to then also have a fire protection system?
    Batteries are used as banks to provide UPS for some businesses so they can either withstand a cut until the generator kicks in or until they can get things shut down correctly.

    Regarding feeding back into the grid, I think it should be much easier, especially with PV as its available when its needed (daytime) unlike wind which can be anytime and also when home owners might be more likely to be out so miay not be as able to use it.

    Whats the physical equipment in a connection line from grid to meter?
    IS it PV panel/array-grid tie (inverter),-cut off device, (or is that part of the inverter?) and then consumer unit-meter


    I see someone else has answered, I still thought it was possible to connect to the grid, just that its not economically viable as you pay more for what you buy than what you export to the grid, whats the maximum allowed for a domestic connection in terms of power/kwhs?

    and I think a bigger thing, why isn't PV or grid tieing favoured by the network operator?
    PV especially in areas near large lines should not be an issue? maybe if someone was down the country (possibly might have a wind turbine, but maybe PV or both), there might be an issue if the line size wouldnt have the capacity to manage a lot of individual inputs? or is it a power factor concern? or is it an institutionalized view?
    The grid is being upgraded, so why? or why not?


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    #13
    quentingargan
    Registered Users Posts: 1,627 ✭✭✭quentingargan


    cerastes wrote: »
    I suppose a battery could be costed into things,
    But I dont know if that would not make it viable then or so less viable that its not worth it due to less predictable circumstances, like if a battery fails.
    Regarding batteries Id wondered would this affect a standard domestic scenario or could they even be put in a house? insurance? Maybe if you had a garage but that might mean extending wiring down from a solar PV panel/grid and then back where you need it. Id still probably want them in some kind of ceramic container and I wonder if you'd have to then also have a fire protection system?
    Batteries are used as banks to provide UPS for some businesses so they can either withstand a cut until the generator kicks in or until they can get things shut down correctly.

    Regarding feeding back into the grid, I think it should be much easier, especially with PV as its available when its needed (daytime) unlike wind which can be anytime and also when home owners might be more likely to be out so miay not be as able to use it.

    Whats the physical equipment in a connection line from grid to meter?
    IS it PV panel/array-grid tie (inverter),-cut off device, (or is that part of the inverter?) and then consumer unit-meter


    I see someone else has answered, I still thought it was possible to connect to the grid, just that its not economically viable as you pay more for what you buy than what you export to the grid, whats the maximum allowed for a domestic connection in terms of power/kwhs?

    and I think a bigger thing, why isn't PV or grid tieing favoured by the network operator?
    PV especially in areas near large lines should not be an issue? maybe if someone was down the country (possibly might have a wind turbine, but maybe PV or both), there might be an issue if the line size wouldnt have the capacity to manage a lot of individual inputs? or is it a power factor concern? or is it an institutionalized view?
    The grid is being upgraded, so why? or why not?

    It isn't just a battery- you would need other components including a separate battery inverter to convert battery voltage to the grid. If you have reason to want a UPS system, it is very feasible to have solar PV meeting your household electricity needs, but a bit expensive for most.

    I think the network operators in Ireland like large central generation. It is up to the politicians and regulators to mandate that they must buy electricity from microgenerators.


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    #14
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    quentingargan wrote: »
    It isn't just a battery- you would need other components including a separate battery inverter to convert battery voltage to the grid. If you have reason to want a UPS system, it is very feasible to have solar PV meeting your household electricity needs, but a bit expensive for most.

    I think the network operators in Ireland like large central generation. It is up to the politicians and regulators to mandate that they must buy electricity from microgenerators.

    Not on boards for a few days, I did mention an inverter, but my intent when mentioning such a component was to convert battery power for use by standard items that run off/use 230 Vac.
    It would be nice to export to the grid to maximise the benefit and use of a pv panel, where essentially others can benefit from its installation and whereby the installer/operator get paid for it and at a rate that's a benefit to them as a bonus for generating electricity, but it seems like its a costly venture t get involved in grid tie and with no financial rewards no one can get a benefit from it, not the network of the individual.
    I'm wondering if the disadvantages for the grid are a power factor issue where domestic micro generators might have to compensate the grid operator technically and maybe financially? Perhaps balancing on different phases where its likely one person would be using one phase in a domestic scenario.
    For all the above, I think an off grid scenario makes more sense wherea/your PV array woulld run certain tyings in your home, ie a set certain plug sockets lights and maybe a resistive load into an immersion heater t utilise any power venerated when it's not required elsewhere in the home, even if you just broke even, you could probably outstrip rising costs and have a reliability and independence from rising costs and on the rare occasion the grid goes down locally have independence of supply.

    Exporting to the grid makes more sense, as there will always be someone that will want to use it if you are out of the house and you aren't getting further benefit from heating a water tank or its shut off for other reasons such as a Max temp attained.


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    #15
    GreenTech
    Closed Accounts Posts: 26 ✭GreenTech


    Hi William,

    Just to go back to the original question 'will it work?' .... i think the answer depends very much on how much energy it takes to heat the building. The reality is, if you have a cottage with solid stone walls and no insulation, coupled with single glazed windows, poor roof insulation etc. then the heat losses will be very high. If this is the case, whether you install solar thermal or solar PV is irrelevant from my perspective, as the demand will be highest in the winter when both solar thermal and PV will be at their least efficient. A solar water heating system generally only performs to about 10% of it's capacity mid winter, therefore when you need the heat most it is simply not performing and you need to boost it somehow (ie. a boiler or heat pump etc.). On the other hand you will be producing excess heat in the summer months if the house is vacant. Solar thermal heating systems can be efficient in a well insulated home where underfloor heating only requires circulation temperatures of 25 degrees, or thereabouts, as the solar thermal will provide low temperature water heating even i winter, albeit during hours of sunlight only. The same issue may occur with a PV system. If you install a PV array with electrical heaters you will produce the bulk of your power mid-summer. Mid winter you will be pulling electricity from the grid. The first question is, how does you cottage retain heat? The second is, how can I improve this?... and the third, what is the best system to maintain the buildings temperature in the depths of winter.

    If this is just an untouched cottage (solid stone walls with no insulation) then my advice would be to install a system which can run at night as well as during the day. Unless the building is well insulated and requires very little heat to maintain a 20 degree indoor temp in winter, you could end up spending a lot of money on a system which works best when you least need it (in the summer) and requires back up from the national grid or from a boiler, when you need the heat most. I have a lot of time for solar PV and solar thermal systems, but they are generally incorporated as part of a low energy design or retrofit scheme, where reducing heat demand is prioritised and supplemented by renewable energy technologies to maximise the efficiency and payback of renewable heating systems for the end user.


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    #16
    quentingargan
    Registered Users Posts: 1,627 ✭✭✭quentingargan


    GreenTech wrote: »
    I have a lot of time for solar PV and solar thermal systems, but they are generally incorporated as part of a low energy design or retrofit scheme, where reducing heat demand is prioritised and supplemented by renewable energy technologies to maximise the efficiency and payback of renewable heating systems for the end user.
    Agree totally. Also with your points that solar for space heating works best when you need it least, regardless of whether it is PV or thermal.

    I used to have an old cottage like this. I found the enemy was damp rather than cold. Dehumidifiers working at night or mechanical ventilation might be a better option?


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