Taking advantage of a goofy tariff (Cosy Octopus)
I have just (today!) joined the happy band of Sunsynk system users with 5.6kWp of PVs, an 8kW inverter and two 5.32kWh batteries. My question relates to how best to make use of the UK Cosy Octopus tariff which runs like this:
04:00 hrs to 07:00 hrs cheap rate (40% cheaper)
13:00 hrs to 16:00 hrs cheap rate (40% cheaper)
16:00 hrs to 19:00 hrs penalty rate (60% more expensive)
At all other times the "normal" rate applies.
I have programmed my car charging times (a plug-in hybrid) and my heat pump (heating and hot water) to take advantage of the cheap rates and avoid the penalty rate.
It seems to me that the batteries on the inverter are a little more complicated and I would like to get opinions on how I could best set up the system.
The early-morning cheap rate, I think, is probably a no-brainer. 4am to 7am looks like a good time to charge the batteries pretty much regardless.
The afternoon cheap rate is, however, something I have never met or thought about before. It seems to me that charging from the grid during this period has a potential downside. You could be using battery capacity to store cheap rate electricity which COULD have been used to store FREE electricity from the panels.
I am struggling a bit to get my head around this last bit.
Does anyone have any insights which could make this easier to figure out?
I am willing to experiment a bit and won't be devastated if I don't hit the sweet spot right away!
