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PV panels

  • 26-07-2020 7:18pm
    #1
    Registered Users Posts: 2,941 ✭✭✭ teednab-el


    Going with air 2 water in my house. I have a garage almost 30 meters away from my plant room in house where air to water unit is and the outer a2w unit will be located.

    Is it possible to put pv panels on roof of garage and use them to help heat water for house without relying 100% on the a2w heat pump? I don't want the pv panels on the house roof tbh.

    If provisions need to be made for pv panels for my scanerio what needs to be done? There is no air to water system in yet. I have fuseboard in garage.

    Do i need underground electrical wires to go from garage to house or are there other factors that would be required? Would pipes or control systems have to go in too? I would like to know more about it first.


    PV panels wouldn't be going in now but maybe in the future. I could make provisions if possible for them.

    Thanks


Comments

  • Registered Users Posts: 412 ✭✭ Mr Q


    I don't know what type of heat pump you are installing but it is extremely unlikely the manufacturer would recommend a distance anywhere near 30 metres between the two units. I would think 10 to 15 metres is the max.

    Why can't you install the heat pump unit outside of the wall of your plant room or as close as possible?


  • Registered Users Posts: 2,941 ✭✭✭ teednab-el


    Mr Q wrote: »
    I don't know what type of heat pump you are installing but it is extremely unlikely the manufacturer would recommend a distance anywhere near 30 metres between the two units. I would think 10 to 15 metres is the max.

    Why can't you install the heat pump unit outside of the wall of your plant room or as close as possible?

    My heat pump is outside on wall of my back door. Plant room is located inside that wall. The problem is if i want to put pv panels in future. I don't want them on the roof of house. I was hoping to put them on the garage roof instead. The garage is 30m away from back door.


  • Registered Users Posts: 412 ✭✭ Mr Q


    Misread that, thought it was that the inside unit is in the plant room and the outside A2W unit will be 30m away in the garage.

    Some heat pumps can be integrated to use excess PV, have you purchased it yet? Using the PV directly to heat the water wouldn't be as efficient as this if your HP can do it


  • Registered Users Posts: 2,941 ✭✭✭ teednab-el


    Mr Q wrote: »
    Misread that, thought it was that the inside unit is in the plant room and the outside A2W unit will be 30m away in the garage.

    Some heat pumps can be integrated to use excess PV, have you purchased it yet? Using the PV directly to heat the water wouldn't be as efficient as this if your HP can do it

    I was hoping for the pv panels to help to heat our water so that the Heat pump wouldn't be using electricity to heat the water.

    Plan was to put the pv panels on garage in future but just make provisions for them now during building stage. Worth doing or not?


  • Registered Users Posts: 2,941 ✭✭✭ teednab-el


    teednab-el wrote: »
    I was hoping for the pv panels to help to heat our water so that the Heat pump wouldn't be using electricity to heat the water.

    Plan was to put the pv panels on garage in future but just make provisions for them now during building stage. Worth doing or not?

    Anyone? I still dont know if i will go with the idea as I can't get enough information on it.


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  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    teednab-el wrote: »
    Anyone? I still dont know if i will go with the idea as I can't get enough information on it.

    I would recommend you make provision for installing PV but not on the basis of heating hot water.

    Heating hot water with your heat pump should cost <€150/yr so you won’t save anything substantial by heating it with PV as PV would only cover a fraction of that and most PV hot water diverters cost extra so it won’t pay for itself in any reasonable time.

    PV is to be used to reduce your daytime electricity usage... i.e the expensive 16c/kWh electricity.

    To make provision for PV keep space for the inverter near your fuse board and a duct between the house and garage is a good idea regardless.

    You should also make provision for an electric car charge point. You might not need it for 10yrs but you will at some point. Put a standard external socket on an outside wall where you could charge an EV from. It needs to be a dedicated circuit with a 40A capable cable. The dedicated circuit bit is critical. If/When you get an EV you can then easily swap the socket for a charge point without having to run cables (digging/drilling etc).


  • Registered Users Posts: 2,941 ✭✭✭ teednab-el


    I have the electric car charger cable in. I don't have the pv panel cables in as of yet. I dont have 2nd fix electrics done yet or ducts for the wires or cables to the garage. It was an after thought but seriously thinking of putting it in before its all done.


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    teednab-el wrote: »
    I have the electric car charger cable in. I don't have the pv panel cables in as of yet. I dont have 2nd fix electrics done yet or ducts for the wires or cables to the garage. It was an after thought but seriously thinking of putting it in before its all done.

    You dont need to put in the wires. Just have the duct. Depending on what you buy you may need to pull extra cables anyway so no point in second guessing what you will need in 5-10yrs time... just get the ducting in so that its easy for you to get cables between the two fuseboards without getting out the hammer.


  • Registered Users Posts: 2,941 ✭✭✭ teednab-el


    KCross wrote: »
    You dont need to put in the wires. Just have the duct. Depending on what you buy you may need to pull extra cables anyway so no point in second guessing what you will need in 5-10yrs time... just get the ducting in so that its easy for you to get cables between the two fuseboards without getting out the hammer.

    Would you put draw wires in with the duct?


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    teednab-el wrote: »
    Would you put draw wires in with the duct?

    Ideally, but no big deal if there isnt one. Its fairly simple to pull a draw wire later.... having the duct in is the main thing as runnning cables after can be a nightmare... even more so in the case of getting between a garage and the house.


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  • Registered Users Posts: 76 ✭✭ Energy1


    teednab-el wrote: »
    I was hoping for the pv panels to help to heat our water so that the Heat pump wouldn't be using electricity to heat the water.

    Plan was to put the pv panels on garage in future but just make provisions for them now during building stage. Worth doing or not?

    I have a device called an eddie, basically using CT clamps it checks what electricity the house is using, it checks what power the panels are producing and if you are producing more power than the house uses it diverts the excess power to heat the immersion. I have a small 1.2kW system which came with my house, the house is A rated so the power we use is low as all appliances are A rated too. I found for 3/4 months we have hot water every morning without putting on the gas, this is all from the excess power the panels produced.

    I am in the process of a new build and will 100% install PV panels. Mainly to power a battery, charge an electric car and any excess heat the water and therefore as you mention reduce the need for the heat pump. As someone else mentioned its more efficient to use the heat pump to heat the water but the eddie uses excess power that would otherwise not be used. Hope that make sense.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,822 CMod ✭✭✭✭ unkel


    A lot of unwise decisions there, Energy1. With a 1.2kW PV system, the Eddi will never ever pay for itself. Even if you bought the part second hand and installed it yourself.

    Also charging the car from the battery is a very bad idea. It literally is cheaper to charge it from the grid at night rate

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



  • Registered Users Posts: 76 ✭✭ Energy1


    unkel wrote: »
    A lot of unwise decisions there, Energy1. With a 1.2kW PV system, the Eddi will never ever pay for itself. Even if you bought the part second hand and installed it yourself.

    Also charging the car from the battery is a very bad idea. It literally is cheaper to charge it from the grid at night rate

    I did put it in myself, I know from March till August I didn’t have to put on hot water for showers. Maybe it won’t but I bought it as I am building a new house and intend to bring it with me in two years.

    I know nothing about night rate, will it not be cheaper when the PV panels generate power during the day at no cost? Of course you have to factor in the cost of the system. A zappi ensures it only takes from the PV system not grid. Sorry I am only asking as I’m new to all this and interested to learn more.


  • Moderators, Society & Culture Moderators Posts: 31,247 Mod ✭✭✭✭ Gumbo


    Energy1 wrote: »
    I did put it in myself, I know from March till August I didn’t have to put on hot water for showers. Maybe it won’t but I bought it as it building a house and intend to bring it with me.

    I know nothing about night rate, how works it be cheaper when the PV panels generate power during the day at no cost? Of corse you have to factor in the cost of the system. A zappi ensures it only takes from the PV system not grid. Sorry I am
    only asking as I’m new to all this and interested to learn more.

    Add the cost of buying the eddi.
    Then work out how much it actually sends to the immersion.
    Then work out how long it will take to pay back that cost.

    Same for your comment about charging a battery in turn to charge a car. That’s not how it works. Domestic batteries are 5 kWh give or take. Your EV could be 64 kWh. So you’d drain the battery completely while putting very little into the car.

    Same for the zappi. The car needs a minimum amount of power in order to trickle charge and in some cars that’s 1.2–1.4 kw. So the 1.2 kw system may never be able to send the excess to the car.
    What EV do you have or plan to buy? As some can commence a charge lower than others. But, with most charging at 7kw at home I don’t think you’ll ever be charging your EV, while heating water and filling the battery. We are not there yet.

    Now, I’m not totally against your set up. Just sit down and do the numbers with someone that’s not trying to sell you the system.

    I have an eddi myself. But I installed a 3 kw system with Eddi for €2900 3 years ago. At that time it made sense. I’m
    Also adding a 5.2 kWh battery next week and an additional 2.04kw of panels but again, it’s self install through my mate so meet cost is €1k to me.

    Zappi is great but the costs don’t add up and I’m driving an EV since 2016 too.

    Night rate is 9c per kWh.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,822 CMod ✭✭✭✭ unkel


    Energy1 wrote: »
    I did put it in myself, I know from March till August I didn’t have to put on hot water for showers. Maybe it won’t but I bought it as it building a house and intend to bring it with me.

    Ah that makes a lot more sense. In your new build, make sure you plaster the roof with panels :)

    And in all of this of course, money is not the only consideration. For a lot of us in here there is also the intention to do our bit against climate change and to go renewables. And in many cases it turns into some sort of hobby too! It's always good to be aware of how much a system costs and how much it saves you though.

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



  • Registered Users Posts: 76 ✭✭ Energy1


    Gumbo wrote: »
    Add the cost of buying the eddi.
    Then work out how much it actually sends to the immersion.
    Then work out how long it will take to pay back that cost.

    Same for your comment about charging a battery in turn to charge a car. That’s not how it works. Domestic batteries are 5 kWh give or take. Your EV could be 64 kWh. So you’d drain the battery completely while putting very little into the car.

    Same for the zappi. The car needs a minimum amount of power in order to trickle charge and in some cars that’s 1.2–1.4 kw. So the 1.2 kw system may never be able to send the excess to the car.
    What EV do you have or plan to buy? As some can commence a charge lower than others. But, with most charging at 7kw at home I don’t think you’ll ever be charging your EV, while heating water and filling the battery. We are not there yet.

    Now, I’m not totally against your set up. Just sit down and do the numbers with someone that’s not trying to sell you the system.

    I have an eddi myself. But I installed a 3 kw system with Eddi for €2900 3 years ago. At that time it made sense. I’m
    Also adding a 5.2 kWh battery next week and an additional 2.04kw of panels but again, it’s self install through my mate so meet cost is €1k to me.

    Zappi is great but the costs don’t add up and I’m driving an EV since 2016 too.

    Night rate is 9c per kWh.

    Yeah you are correct and its not straight forward to calculate!! I didnt do the maths but gas was on for half hour every day for 5 months and with the eddi it wasnt!! Gas is cheap though. Is the best set up to use the battery during the day for house load and top up the battery with the PV during the day? Has your system every maxed out in terms of battery and load therefore eddi diverts to the immersion? Have you A2W? I am interested to see how often it tops up the water and if PV systems would be good to use, not sure if its a trickle charge as the water is used or what way it works.

    Tesla is the car I will be buying (Hopefully) I have seen videos on you tube and the houses are self sufficient but I personally need to do the maths as I find alot of companies are selling to make money and not help the customer have a system to suit their needs.


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