I have been asked a quizzer by someone looking to install a Victron Energy Storage System.
Here in South Africa, the mindset is very much about resilience to power failures, either as a result of local grid failure or "Load Shedding" by the national generating entity.
However, this person is an immigrant from Germany and they want a solution that optimises for reducing their expenditure on the utility even if that is at the expense of resilience to grid failure.
My thinking has always been: "Batteries are there to provide backup in the event of grid failure. Therefore you want them to be fully charged so they can keep things running as long as possible, ideally until the grid returns".
However, this person wants to make use of battery power during high demand periods in the day and charge them during low demand periods. They then want the batteries to supply power in the evening, again to reduce usage of the grid. I think there is some sense to this but I'm just feeling it with my fingertips.
To provide power in the evenings, by the end of the day, we will want the batteries fully charged. So, one might say that before 14h00 each day, the batteries can be used to supplement supply but only to 70% SoC. Below 70% or after 14h00, batteries must charge back to 100% before being used to supply again.
One might equally say that in the morning, the batteries must get back to 100% before they are used to supplement supply. That might only happen at 10h00. Thus, the batteries would be supplementing supply between 10h00 and 14h00 in that example.
Is something like this configuration possible with a Multiplus II 48/3000, Lithium Batteries and MPPTs?