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Thanks!

5kw lithium iron phosphate battery

With the objective to maximize electricity and carbon savings without killing my battery (if that is even still a thing).

Hi, I am interested in any strategies folks are following with their evening drawdown of their household lithium ion batteries now that we are not currently loadshedding? I previously did not go under 40% for most timeslots and 60% in the early evening to avoid blackouts. Am considering going a bit more aggressive! Cheers Stephen

We have our geyser on the non-essential load and a timer. It works great. We have an existing Geyserwise system, and essentially use that only to give a digital reading on water temp. And we use it as a convenient place to turn off geyser when needed. But absolutely not needed. The timer is set to only be on in the day and we have cranked up the temp to the highest possible to make sure that we maximize the solar contribution and make sure that the stock of hot water lasts through the evening.

all indications are that batteries will be cheaper and better in ten years time anyway, so things should not be economically worse than the current case.

Agree it is not rational, but it is a fun challenge to drop the usage! I am not too worried about getting it wrong on the worst case scenario you have set out (especially as PE loadshedding is in 2 hr blocks), but am more concerned about over-stressing battery with the greater DOD. Not sure if that is a big deal or not.

Yip "independent and have uninterrupted service" definitely is worth a lot! So far I would probably not have needed any Eskom if I had another battery, but that would have been excessive cost for benefit I think. I currently let the battery DOD go down to 40%. Am wondering whether I should let this drop lower - possibly to 30% in early morning?

Thanks - how do we access this sort of info?

Hi everyone, Just for interest. We have a Sunsynk 5kw, 5kwh battery, approx 130k system, with a small household. Existing partial solar water heater. Electric stove and pool pump. Since installation at the beginning of the year we are managing to get just over 90% of electricity from solar. Interested in other experiences out there. Stephen

A follow-up response based on the efficiency issue. I have piles of excess solar in the day so am not sure the round trip efficiency is a big deal, only the efficiency in getting from stored battery to use. By my reckoning that halves the correction needed.

Rather split into two series as otherwise some minor/ partial shading or similar will drop performance on all panels, rather than just half. One series may be ok if identical and all pointed in exactly the same direction and no shade ever.

Thanks very much. That is helpful. It appears that based on the sort of numbers one comes out with that it would inevitably be cheaper (so long as one is not exceeding discharge limit) to prefer cycling the battery down rather than topping up with Eskom when in all likelihood the sun will come up at some point.

Should also say, we generally are not drawing anything from Eskom, just enough to stop the current reversing or the meter tripping.

Hallo, I have got a new 5kw pv system on a residential house, sunsink, 5.5 kwh lithium battery and 8 x 550w panels. Also older solar geyser. At the moment, if we hit evening with a full battery, after the evening use the battery gradually draws down to about 45-50% in the early morning before the sun kicks in. The grid recharge threshold is set at 40% SOC. My question, in the long term what is the optimum depth of discharge for a 5.5 kwh lithium battery?? We would like to minimize Eskom costs and carbon. We are not worried about "bad timing of loadshedding and cloudy morning" and am not worried about keeping the battery full just in case. But we don't want to have our battery dying prematurely. Based on current economics of batteries and Eskom prices, should we be charging more (or less) from grid in the early hours? Could we safely run the battery down more each night? Or is the cost in battery life worse than the cost of electricity to recharge a bit?