We have a new system installed a week ago, Inverter 5.0 and Battery 9.5. Callibration ran successfully. Since then the weather has not been kind so the battery has not gone much above 15-20%. System is just on ECO mode. I am on a 2 year fixed rate so no cheap periods.
My question is should I set the system to run a timed charge to a certain % daily as its not charging much at the moment or is it ok at these lower levels and just wait for soime sunny days?
Thanks.
Do you have cheaper periods of energy?
I had my system installed last week, and after initial calibration have just left it on Eco for any excess solar to charge it. Got to 85% on Monday and up to 35% today.
My thinking is charging it from the grid and using it from the battery is less efficient than the house just pulling what it needs from the grid. I'm on Octopus Tracker, which is one rate all day, but if I had a cheap overnight tariff then I'd fill it up and whack on the washing machine/dishwasher.
My battery did get down to 4% this morning, then gradually 0% at which point the grid charged it back up to 4% so it seems it's being looked after.
@Hook
No just a set tariff of 18.52p.
I will change when the fixed period ends but just not sure as the battery is not being topped up much each day due to cloudy days.
As its fixed rate I could top up 50% overnight to keep the battery turning over but not sure if its worth it or not.
mdb Would just seem like needless cycles on the battery without any benefit to me.
I don't know the efficiency of charging/discharging the battery, but I'm sure it's not 100% efficient, so you'd be effectively losing out if you're on a set tariff.
I agree. On a fixed rate, there is no point in charging the battery from the grid and then using that in the house. You are going to be wasting money on the round efficiency (85% as a worst case scenario).
Charge only from solar, use as much as you can, and leave the house to draw from the grid if the battery is empty. Eco mode all the way.
I would suggest charging to 100% periodically, say once every 2 weeks, so that the %SoC is calibrated to some extent, and the individual cells within the battery pack have the voltages evened out by the battery management system.
There are multiple threads on this forum with reports of the calculated %SoC not matching the real state of the battery with consequences on the charge/discharge cycles and the effective capacity being usable in the short term.
In the Summer this will require much less or no grid charging due to the higher solar PV generation.
I’m currently doing a couple of test overnight charges (installed last week) to see how much battery I need in the earlier parts of the day on these cloudier days, but will be leaving mine on eco only for a few weeks until I swap over to the flux tariff as there no advantage to charging a battery at the same rate I can get it from the grid!
Hook from my spreadsheet since the start of the year there is 12% less coming out from the battery than went in.
BarleyRiser Just looked at mine since it was commissioned. 88.75%, so pretty similar.
I wonder how efficient those with multiple batteries are in comparison.