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Solar PV - Excess from 2.1kw system?

  • 10-05-2021 10:38am
    #1
    NobodyImportant
    Registered Users Posts: 585 ✭✭✭


    Hi all,

    Looking to get a solar as a service job soon, and thinking about the upgrade to dumping excess energy into the hot water tank. I know it wont pay for itself, but more interested in having hot water during the sunnier months.

    Will there be much excess though? We've used nearly 10k kwh in the last year (because of working from home), but are a bit of consumer in energy, I put it down to the granny flat and a lot of devices always on, like 2 x routers, 3 x wifi repeaters, security cameras, 3 fridges etc etc. No point paying over the odds for this H/W function, it the house will suck up most of the energy produced anyway.

    So would there be excess energy from the basic system in the good months to give us some free hot water?

    Anything else I need to look at? I plan to ask the company to install a larger Inverter at my cost, so i can add more panels in the future as cash allows - we may end up with an electric car at some point. Not interested in batteries given their cost and how long it will take to break even.

    Thanks!


Comments

  • #2
    TheWonderLlama
    Registered Users Posts: 588 ✭✭✭TheWonderLlama


    I would get a battery before a diverter if i were you. I have both and find that the battery is infinitely more useful and helps with overall reduction of costs.
    Added to that, that in the future, you may be able to take part in dynamic pricing with a battery like they currently can in the UK (see Octopus Energy for an example)

    Difficult to say what your excess might be, do you have a monitoring app for the current setup?


  • #3
    NobodyImportant
    Registered Users Posts: 585 ✭✭✭NobodyImportant


    I've ordered an owl monitor to try measure the idle consumption of the house.

    Isnt a battery multiple times that of a diverter? The options on the website is (after grant), 2.1kw system, €20 pm, 2.1kw system with diverter, €35 a month, then 2.1kw system (I assume), plus diverter and battery is €72 a month. So a large difference adding in the battery, and it doesn't feel like I would see that money back for looooonnnnnggg time.


  • #4
    slave1
    Moderators, Sports Moderators Posts: 18,675 Mod ✭✭✭✭slave1


    Avoid a battery, not only will you have the battery cost but the Inverter will be double the cost of non-hybrid inverter.
    Understand your house load first, while you may have excess PV how useful is it to heat the water, I'm heating the water right now at 2.7kW but how useful is say, 200w at heating water, not great I would say...

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  • #5
    TheWonderLlama
    Registered Users Posts: 588 ✭✭✭TheWonderLlama


    over what period are those repayment amounts for?

    a 2.4Kw Pylontech battery recently cost me just over 1,100 to buy. There would be some installation costs on top, but you should be able to get one in for under €2k

    Might be worth having a nose through this thread to see the comparative prices for other systems before committing.

    https://www.boards.ie/vbulletin/showthread.php?p=112573896


  • #6
    SouthWesterly
    Registered Users Posts: 6,454 ✭✭✭SouthWesterly


    TheWonderLlama wrote: »
    over what period are those repayment amounts for?

    a 2.4Kw Pylontech battery recently cost me just over 1,100 to buy. There would be some installation costs on top, but you should be able to get one in for under €2k

    Might be worth having a nose through this thread to see the comparative prices for other systems before committing.

    https://www.boards.ie/vbulletin/showthread.php?p=112573896

    It's over 10 years.
    Quiet a few here have gone with them.

    I'm about to pull the trigger as well.
    They would have advised you against the battery or inverter on a 2.5kw system.


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  • #7
    TheWonderLlama
    Registered Users Posts: 588 ✭✭✭TheWonderLlama


    well, I always had a plan in mind of adding to the system as I could, so i overspecced the basic stuff up front.

    Now have a second battery, a diverter zappi and getting more panels installed up to the max I can. Looking to get an air to water system installed and possibly an off-grid system on my garage as i have really seen the difference in the electricity/heating bills. Goal is to be as independent of the grid as i can, but always have it there. i suppose it depends on what you want the system to do for you.


  • #8
    unkel
    Registered Users Posts: 64,745 ✭✭✭✭unkel


    TheWonderLlama wrote: »
    a 2.4Kw Pylontech battery recently cost me just over 1,100 to buy.

    Jesus. How much is the total cost of having it installed including the upgrade to a hybrid inverter / standalone battery inverter and install charges?

    How much do you expect this system to save you per year? Or did you do it mostly do be less dependent on the grid and to have a little backup power?


  • #9
    TheWonderLlama
    Registered Users Posts: 588 ✭✭✭TheWonderLlama


    already had the hybrid inverter and one battery, this was just a 2nd because I could see that we were pumping a lot units back into the grid during the day.
    Also had them install a zappi at the same time.

    I have a smartmeter installed and once I reach the end of my contract with current energy provider, I will be moving to a day/night rate with the idea being to charge the batteries at night, use them during the day to charge the EV and run the house and ultimately to get an A2W heat pump to get rid of the oil heating.

    The off-grid system is a long-term project and I will be trying top pick up cheap panels to DIY it.

    I know i will never get to zero grid, its just unrealistic for my situation, but i'm happy to plug away upgrading the house and reduce fossil fuel usage where i can.


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