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Solar PV - should I get a battery?

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  • 08-02-2021 4:31pm
    #1
    purethick
    Registered Users Posts: 172 ✭✭


    Would anyone be able to offer some advice on what factors (apart from cost) are relevant in relation to whether a battery is needed with a new PV system?

    - South facing house (Dublin)
    - Currently use about 3,500kWh per annum
    - No immersion (have a gas combi boiler)
    - House is occupied during the day
    - Looking at a PV system in the region of 2.6-3.0kW

    If the system is too small to warrant a battery then is it safe to assume that at some point soon(ish) we'll be able to feed unused energy into the grid with a smart meter and be paid for it?

    Thanks


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    #2
    KCross
    Registered Users Posts: 12,076 ✭✭✭✭KCross


    purethick wrote: »
    If the system is too small to warrant a battery then is it safe to assume that at some point soon(ish) we'll be able to feed unused energy into the grid with a smart meter and be paid for it?

    https://www.boards.ie/vbulletin/showthread.php?t=2058149744


    July 2021 is the target date.


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    #3
    uphillonly
    Registered Users Posts: 287 ✭✭uphillonly


    We only had our Solar PV installed in Dec 2020 so my data is limited. Dublin, 5.8kWh battery. 2.8kW array facing south. The 3.2 kW East facing array is shaded for a few more weeks until sun rises further so only producing a few hundred watts and not relevant to your question.

    With this set up from December the battery receives some charge every day. Highest state of charge so far: 49%. Everything the panels produce we consume. So the battery is definitely being used regularly even in these shorter months. When it starts reaching 100% regularly we'll leave the EV plugged in for surplus trickle charge on the Zappi.

    Economically I understand the payback is questionable but it's nice to know we're using all we produce and helping the grid a little.


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    #4
    Calahonda52
    Registered Users Posts: 12,220 ✭✭✭✭Calahonda52


    uphillonly wrote: »
    We only had our Solar PV installed in Dec 2020 so my data is limited. Dublin, 5.8kWh battery. 2.8kW array facing south. The 3.2 kW East facing array is shaded for a few more weeks until sun rises further so only producing a few hundred watts and not relevant to your question.

    With this set up from December the battery receives some charge every day. Highest state of charge so far: 49%. Everything the panels produce we consume. So the battery is definitely being used regularly even in these shorter months. When it starts reaching 100% regularly we'll leave the EV plugged in for surplus trickle charge on the Zappi.

    Economically I understand the payback is questionable but it's nice to know we're using all we produce and helping the grid a little.

    Are you charging the battery at night on the night rate and use it during the day?
    The FIT when it comes in will be less than miniscule

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    #5
    slave1
    Moderators, Sports Moderators Posts: 18,742 Mod ✭✭✭✭slave1


    uphillonly wrote: »
    We only had our Solar PV installed in Dec 2020 so my data is limited. Dublin, 5.8kWh battery. 2.8kW array facing south. The 3.2 kW East facing array is shaded for a few more weeks until sun rises further so only producing a few hundred watts and not relevant to your question.

    With this set up from December the battery receives some charge every day. Highest state of charge so far: 49%. Everything the panels produce we consume. So the battery is definitely being used regularly even in these shorter months. When it starts reaching 100% regularly we'll leave the EV plugged in for surplus trickle charge on the Zappi.

    Economically I understand the payback is questionable but it's nice to know we're using all we produce and helping the grid a little.
    You mention surplus trickle for Zappi, it needs to be 1.4kw minimum so given your house load it will be interesting to see what months you can charge the car

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    #6
    uphillonly
    Registered Users Posts: 287 ✭✭uphillonly


    Calahonda52 wrote: »
    Are you charging the battery at night on the night rate and use it during the day?
    The FIT when it comes in will be less than miniscule

    No, no night charging yet. I've read the debates on the savings versus reducing battery life. Holding off for the moment.

    slave1 - re Zappi. One of my neighbours said he only trickle charged the car from Zappi between April and October. Nothing from the grid. Daytime working from home, our base is 400-700w ignoring the occasional kettle etc. We've already had peaks up to 2,700w without the east array getting direct sunlight yet so I'm hopeful we'll have some sustained higher generation as the sun rises higher. Should be enough to cover usual weekly driving around town. Will be interesting to monitor.


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