What should SOC be set to during UK winter?
Hi everyone. New to the forum. Just had my system commissioned this week.
3.6KW Inverter
5.1KWh battery
6KW panels split into 2 strings on the front and side of roof
UK winter so managing expectations for now obviously.
My installer said that I should set the SOC to 15% across the board and that he'd been told during his training course with Keith that is how it should be. I'm a bit worried about this. In the UK winter we're barely covering the house load during the day with the solar and the battery is just constantly sat at 15%. Sometimes around peak time in the day it will get up to the heady heights of 18% by using a bit of excess from the solar but obviously as soon as someone turns something on it goes right back down to 15% as it's used up.
Now bear in mind that the weather is like this from Oct to Mar in the UK. Doesn't that mean that the battery is basically going to be sat at 15% for all that time, 4-5 months. Barely getting even to 20% on the best days? If you were to long term store the battery it should have between 40-50% in it as far as I understand. This is best practice for Lithium batteries isn't it?
My thinking is that the SOC should be set to about 40% minimum in the winter months to protect and get the best life out of the batteries. The solar will never charge it up to 100% in the winter and we don't have any cheap night time grid electricity to use so we don't really want to charge from the grid. Obviously this can be set lower when we start getting more sun and the excess will charge the battery more.
Can someone validate my thinking please.
Exactly. I'd have loved to do that this winter but Octopus aren't taking any more Flexible contract customers, while they play this consumption-shifting game. They say they will start again in April. In my case, since 14th Jan I have had a positive power balance, so wont need to import power again till mid November.