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Solar PV and car charger setup

  • 17-05-2023 8:36am
    Registered Users Posts: 7


    Our solar install just went in this week and I am trying to understand the optimal configuration for it to work well with our existing car charger, eg. how to avoid the car just running down the house battery when plugged in, presume this is not ideal?

    Typically work from home so can have the car plugged in when needed, day or night.

    Just wanted to get some thoughts what would good practice around inverter and car charger settings, based on setup below



    10 x 400w panels

    Solis inverter

    5kw battery

    Eddi diverter and harvi monitor

    Existing car charger setup - wallbox pulsar plus with power meter - charging a phev with 18 kw battery.


  • Moderators, Home & Garden Moderators Posts: 5,767 Mod ✭✭✭✭graememk

    Do you have a day night meter?

    if so put a timer on the car or the charge point to only charge at night?

    Does the wall box support charging from solar? It should be able to detect excess with the power meter. Although the eddi will gobble that up first so it possibly will never see enough power to start unless you turn the eddi off when you want to divert to the car.

    If you are on a 24 hr meter, It doesnt really matter if the power comes from the battery or the grid.

  • Registered Users Posts: 7 KTaps

    Have a smart meter but on a normal 24hr tariff for now.

    What I wanted to avoid was the scenario of just moving energy from the smaller house battery to the larger car one, as that seems inefficient.

  • Moderators, Home & Garden Moderators Posts: 5,767 Mod ✭✭✭✭graememk

    If on a 24 tariff.. it doesn't matter. You aren't trying to avoid a high day rate. If the car uses 5 kwh and the house uses 5kwh your battery is going to be flat no matter where it goes.

    You could just have it charge overnight if you want to avoid battery use.

  • Moderators, Science, Health & Environment Moderators Posts: 4,678 Mod ✭✭✭✭Tree

    The wallbox can do solar out of the box if you have the right type of powermeter. It'll detect export and soak it up if it's greater than 1.3kW. Mine has the wrong type of powermeter, so instead of explaining to the installer that it can be done (it can but they only want to sell eddi's for solar), I use home assistant to trigger and pause charging (with the added bonus of detecting draw down on the battery becuase I get that info from my inverter)

  • Registered Users Posts: 1,927 ✭✭✭keith_d99

    Getting an install done in a couple of weeks and this article was recommended by a mate with your exact problem

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  • Registered Users Posts: 654 ✭✭✭Johnny Jukebox

    Would you mind expanding on this a little ? Background is I have a Garo charger installed for my EV and am about to get panels installed and am not sure if the Garo can support solar as you describe it above ?

    If it can't, can I add an eddi for the EV alongside the eddi for heating the water ?

    Thanks !

  • Registered Users Posts: 1,402 ✭✭✭DC999

    Eddi heats hot water tank, as you say. Zappi only charges EVs.

    You can ignore changing the car charger for now. FIT is ~20c for unused units (if you have a smart meter). And if you charge the EV on a cheap night rate (around the same rate as FIT pays), there is no cost difference. As in don’t need to charge the car from solar.

    Meaning you can leave the Garo in for now. Then in time decide if you want to automate it via Home Assistant (if it allows that, I've no idea). Or could decide to replace it with a Zappi and sell the current one. But you can defer that decision if on a smart meter for reason above.  

    Get as many panels as the roof takes, you can afford, + the inverter supports. Save the money on the Zappi for now. Cheapest time to get more panels is day1 (cost of skilled labour is huge). 

  • Moderators, Science, Health & Environment Moderators Posts: 4,678 Mod ✭✭✭✭Tree

    The OP has a wallbox pulsar, they can do solar with the right power meter. Not sure about Garo at all, but if you have any control over it through a home assistant addon, you can set up your own charging feedback.

  • Registered Users Posts: 1,419 ✭✭✭Big Lar

    I have solar and an Easee charger, use home assistant automation that runs every 20mins to control Easee and immersion, Instead of Eddie and Harvi I have a Shelly Pro2pm (Used to have a 1pm it was close to max current with the immersion so I split immersion across two channels in the 2pm).

    I see that there are HA integrations for Garo and Wallbox also

    * If car is plugged in and awaiting charge or charging and the battery > 65% SOC and Current PV >1600w then start charging @2.1Kw, but if Current PV > 4000w set charger to 4.8Kw.

    * If car is not plugged in or completed charge and the battery > 65% SOC and Current PV 1600w then turn on the immersion.

    * (Night Rate Midnight to 9AM) Set charger to 7Kw

    Have 30Kw battery, 8Kwp of panels and 6Kw inverter, in the winter time I will set the SOC limits to 85%

    Energy usage below of the last week or so for the car charger and immersion

  • Registered Users Posts: 42 arestifamiliar

    I have a wallbox and am just get Huawei inverter/solar installed . Am interested in the details of anyone’s automation around optimizing this setup (no battery -car is 70kw, no diverter).

    am thinking of changing the power sensor for my wallbox to support eco smart and maybe a Shelly for immersion, and maybe power negation too. Are people doing this with HA and if so, how ?

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  • Registered Users Posts: 2,475 ✭✭✭ECO_Mental

    I wouldn't worry too much about it....have you got a smart meter?. If so get on a tarrif with night boost were its super low for 2-3 hours at night. Charge your car at this time at 10cent (or lower from some providers), then export your solar at a FIT rate of 20cent..boom you are making 10cent.

    6.1kWp south facing, South of Cork City

  • Registered Users Posts: 1,419 ✭✭✭Big Lar

    Cheap rate at 2-3hrs wont do much as you would just get 7Kw over that time so that's around 21Kwh into the car, depending on your use that may o may not charge the car fully.

    Suggest if you need more than that then a Day/Night meter would suit better, now you have 9hrs (7Kw X 9h = 63Kwh) to charge the car at a cheap rate and as @ECO_Mental said above then get paid for any export during the day.

  • Registered Users Posts: 2,475 ✭✭✭ECO_Mental

    I do a fair bit of mileage on my EV 37k after about 15months and I have been testing this out over the last few weeks (getting ready my smart meter in 3 weeks, I have a D/N meter atm)with my Zappi just charging the 2 hours every night to see how that works for me and I think it will work out.

    2 hours is 20% battery and if I make sure you plug in every night and get the 20% it should cover 90-95% of my needs for the day ahead. If I find I am down to around 30% I will give it an extra hour or two once a week to bring me back up. If Electric Ireland I had a 3 hour window like Pinergy I think it would be a lot better, but for the vast bulk of people with an EV 2-3 hours every night at low boost rates should keep people topped up.

    6.1kWp south facing, South of Cork City

  • Registered Users Posts: 1,402 ✭✭✭DC999

    Same for us. 2-3 hour slot each night will get it to close to 100%. We certainly have days it only does low mileage so it will always get back to 100% several times a week. But depends on the mileage people do. 

    You can test it without a smart meter. Set the charger to only charge at night for 2 hours and see what % the battery stays at over the week. Then do the same on a 3 hour slot. That determines how much / little time you need. 

    We've an old Leaf so can only charge at 3.6kW - but most won't have that limitation. 

    Of course that EV charging slot is competing with charging batteries + load shifting. On My Energie devices you can set the max amps they will draw so they won't overload your electrics. 

  • Registered Users Posts: 4,424 ✭✭✭Gerry

    Still on 2.4kwh granny charger here and not seeing a massive need for the faster one, considering the outlay. Though our leaf has the 6.6kwh charger.

    My main effort needs to go on a better electricity tariff really.

  • Registered Users Posts: 42 arestifamiliar

    I’m on a D/N meter with electric ireland so get that 2hr window too. Just got. A letter about a smart meter upgrade due to be scheduled so fingers crossed will get that soon

    with electric ireland FIT is 21c , night boost is 11c (new prices nov) night is 19c , so no smarts needed at all, just charge car at night ideally in the 2hr window , just don’t charger car during the day , which I don’t

  • Registered Users Posts: 1,071 ✭✭✭silver_sky

    Set your hybrid inverter to charge at 0A during the window that you charge the EV at night. As the inverter will be "charging" the battery it won't discharge to the car. The house would run from the grid during that time.

  • Registered Users Posts: 1,071 ✭✭✭silver_sky

    2 hours is very short. Mine is 4 hours with energia and that's pretty tight also. I tend to time it to start and run into the regular night rate for the few hours afterwards. So a charge from a low SOC is usually 4 hours at EV rate and 2 hours at night rate for me.

  • Moderators, Science, Health & Environment Moderators Posts: 4,678 Mod ✭✭✭✭Tree

    Welcome to my exact setup.

    I have a huawei and a wallbox. Gave up trying to get the wallbox power meter changed and just did it all in home assistantt ( some scripts around here). I have it set so if the battery draw is longer than 2 mins it turns off.

  • Registered Users Posts: 42 arestifamiliar

    I wrote code to automate the wallbox and while it mostly worked, I figured I was spending too much time on it. I bought the em-112 meter that supports eco mode etc, to replace my old SPM1-100-AC clamp that only supported powerboost, will be installing it tomorrow. Seems the inverse to what you did :)

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  • Moderators, Science, Health & Environment Moderators Posts: 4,678 Mod ✭✭✭✭Tree

    Pretty much, it took longer to explain to the installer what I wanted than to just copy and paste into home assistant :)