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What Next - Is my Solar-PV really Maxed?

  • 05-11-2021 1:03pm
    Registered Users Posts: 107 ✭✭

    It seems at first sight to be: 10kWp arrays with mixed orientations and 12kWh batteries. c6kW export limit on the inverter so as to comply with the ESBN regs.

    But I have some spare roof space and would like to do more for the environment.

    The house is already insulated more or less to the max possible (it's old with a protected facade, net-energy requirement when export is factored is falling but still about 3MWh north of zero per annum). (Urban setting so that wind turbine seemingly not yet viable with current tech.)

    Has anyone else figured out the What Next in this situation?

    To me: Best remaining option with current tech is simply more PV. It would have to be wired so that the 6kW export limit still works, or we'd need to upgrade to three-phase or island the new array from the grid with some dedicated purpose like charging the EV, running DC devices (few come to mind) or possibly sit there with a battery as a backup for grid outages.

    Focus is contribution to the environment. Happy to export for free.


  • Registered Users Posts: 793 ✭✭✭reklamos

    You can limit export at inverter to the grid. Add more PV if needed daisy chain inverters and add more batteries.

  • Moderators, Sports Moderators Posts: 18,814 Mod ✭✭✭✭slave1

    I'd increase the battery setup so you are more self consuming, check out the Solar Battery Options thread, good few of us there with 20kWh+ batteries

    My stuff for sale on Adverts inc. outdoor furniture, roof box and EDDI

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  • Registered Users Posts: 107 ✭✭Coltrane

    Thanks. But unless I'm focussed on managing grid outages, more batteries seem to me to be pretty marginal. In our case, only productive around the shoulders (autumn/spring).

    During the darkest/coldest months, the existing batteries are already oversized (much too large to fully charge). Even when the sun is shining the heat pump tends to hoover up existing-PV production and leave little surplus. The additional battery storage would seldom be used.

    During the brightest/warmest period, the existing PV/batteries are already much too large for the house's energy requirement. The additional battery capacity would quickly fill and the batteries would remain at close to 100% soc for months.

    So even more PV (somewhere!) might be a better option...

  • Registered Users Posts: 2,485 ✭✭✭bullit_dodger

    You got an EV? That's the only thing I can think of that you can easily improve on things

  • Registered Users Posts: 793 ✭✭✭reklamos

    We live in Ireland not Spain :) So even in summer it is very rare to have clear skies for 3 days in a row. With bigger battery you could potentially go of grid for longer periods. I was able to do that this year 11 days in a row and that was with 10kWh battery and 4.5kW PV. All the washing was done, with plenty of hot water and still was exporting to grid. If I had 15kWh I could have stretched this even more.

    During dark months you could leverage bigger battery for night rates.

    If I had space for 10 kW PV or more, I would really consider in getting EV

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  • Registered Users Posts: 107 ✭✭Coltrane

    Yes, but it’s often fully charged already (with the existing PV) during the summer!

    And what I’m really trying to do is generate more (relatively) ‘clean’ energy rather than improve self-consumption.

  • Registered Users Posts: 107 ✭✭Coltrane

    Thanks again. Yes, more batteries could help the environment during winter by shifting demand to the windier hours. But what about the enviro footprint of the batteries…

  • Registered Users Posts: 793 ✭✭✭reklamos

    One thing I know for sure, there is no free lunch. We will see the full impact of batteries in next 10years.

  • Registered Users Posts: 3,958 ✭✭✭mp3guy

    Best to just invest money else where, you are maxed out from an environmental perspective. See this video:

    Aim your investments in a direction that get the attention of bigger players, your existing investment in PV has already made its point. Whacking up another few panels will have negligible effect on the bigger picture.

  • Registered Users Posts: 107 ✭✭Coltrane

    Cheers mp. Believe it or not I previously watched that video!

    Fully agree with your sense of the larger importance of influencing others. Just wanted to give the house another small push, as a tiny, tiny part of a highly complex challenge.

    Hope your own power station continues to go well!

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  • Registered Users Posts: 1,460 ✭✭✭reboot

    My EV won't take a charge below 10 Amps,probably not much to ask from your battery set up,but not doable from my small battery setup,which is designed around 5v USB.I have recently added av100 watt turbine,from a Mayo company for the dark days,5 amp into 12v battery.

  • Registered Users Posts: 107 ✭✭Coltrane

    Thanks. Do you live in a windy location and does the turbine work well? If so, which firm from Mayo?

  • Registered Users Posts: 1,460 ✭✭✭reboot

    I don't live in a particularly windy area,and don't want it always turning,as the PV is pretty good,and if the turbines not at cut in speed,it's not charging,just wearing the bearing out.

    Like most turbines it's 3 phase ac,they sell a rectifier,and you end up with 20v dc off load,100 Watts,enough to charge a 12v battery at 5 Amps.

    It's a manageable size,3 foot across blades,but not easy to mount on a pole.

    Good luck,worth a punt at €200.

  • Registered Users Posts: 1,460 ✭✭✭reboot

    Just found out today,that buying the turbine from the nice folk in Mayo,.ie cost me a fee of £10.16 on my Bank of Ireland Sterling account!

    Card payment in a Foreign currency.

    Hands across the border.

  • Registered Users Posts: 6,587 ✭✭✭SouthWesterly

    What turbine did you get?

    Will be interesting to see developments

  • Registered Users Posts: 1,460 ✭✭✭reboot

    As mentioned above to Coltrane, Mayo company.

    3 phase 100 Watts,20 volts off load. Will charge a 12v lead acid at 5 Amps.

    3 blades total diameter 1 m.

    Low cut in speed,pretty quiet.

    €200 plus rectifier.

  • Registered Users Posts: 1,460 ✭✭✭reboot

    Might be a case for a separate Small scale micro grid thread if people interested.

    Wouldn't want to confuse with big PV thread.