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Fast charging solar batteries at night

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  • 02-07-2024 12:46pm
    #1
    ...Ghost...
    Registered Users Posts: 3,551 ✭✭✭


    I have a serious problem!

    I'm addicted to solar and load shifting and I can't get enough. I blame all of you on here! 😋

    I need a little nudge here, as I am planning the next steps.

    My setup is currently 5kW Solis Hybrid with 5kW of solar and 15kWh LFP DIY storage (another 15 purchased for August), smart meter standard day/night EI tariff.

    For those with larger than 15kWh storage and 3-4 hour super cheap night rate, how do you do it?

    My hybrid inverter will only charge my battery at 5kW. So I can fully charge it in 3 hours, but when I add another battery, most likely another 2 batteries to bring me to 40kWh (usable), the inverter won't cut the mustard. My batteries will all be connected via bus bar. Reason I am looking at 40kWh, is my house uses this on average per day, divided over the year. The solar now supplements this, as does the load shifting with the 15kWh battery but winter is always coming.

    I'm still new at this, but my thoughts are to either:

    a. Add a dumb solis inverter and slave it out the master. Not sure how this would be wired to the batteries, but would allow faster charge AND discharge if I wanted to.

    b. Increase the inverter size to allow for faster charge/discharge, but I would still be limited by the 3 hour window realistically and would rather keep my existing inverter for now.

    c. Add a timed battery charger and connect to the bus bars. I think this is the most feasible option to get additional juice into the batteries, even if I am not able to fill from empty to full.

    If I go with option c, I have some spare ways in the CU, so could safely throw at least 3kW (12.5A) at the batteries, couldn't I?

    If I have 2 batteries and my inverter is throwing 5kW, they are sharing the load, so only charging at 2.5kW (or 10A) each. Now that I am looking at the numbers written down, I could probably just hook up a couple of 10A chargers on timers and let them feed the the batteries via the bus bars. It seems a bit too simple, so what am I missing here?

    What way do you have yours connected lads?

    I would love to add as much juice in as short a time as possible, as I am considering moving to the pinergy 5c 3 hour smart EV tariff. It would mean plugging the EVs in every night to keep them topped up, but I could live with that if I get my rate down that low and run the house off batteries the rest of the time. I would only ever draw from the grid when the house load is high, like when the electric shower is on, or I really need to top-up an EV during the day.

    I'd be interested to know what battery chargers you use, or recommend, either connected to the CU directly, or from a 13A domestic plug. Thanks all in advance for your input on this and other questions I asked elsewhere.

    Stay Free



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