Hi,
winter starts, so I decided to enable DESS again, to be able to cheap-charge from grid. However, to know what to expect, I would have a few questions about the Battery Costs - and how they are used in the system.
First, I’ve setup the battery costs as the info-box describes, simple equation based on capacity, cycles and price leading to 0.03 € per kWh.
Yesterday, at 14 there have been 4.72 kWh from “Solar to battery”, and DESS concludes a price of 7 cents on “battery costs” - how is that calculated?
I assume it’s 0.03 * 4.72 / 2? /2 because “half the costs” is put on charge, half is put on discharge, right?
For Feed-In, I would get about 9 cent / kWh. So, in this case - charging 4.72 kWh to the battery - I missed 42 cent (Opportunity costs) which I would have earned without a battery. These costs seem to vanish? I would have expected to see them as “battery costs” as well, so any kWh going from solar through my battery is not 0.03 but should be 0.12?
This leads to the final question:
How does DESS take the battery costs into account for charging from Grid? I’m mainly interested in unterstanding, when one of the following two decissions will be made:
- Battery empty, use from grid but DONT charge the battery.
- Battery empty, use from grid AND charge the battery for later usage.
Will it decide to charge the battery, when GridPrice + CostsPerKwH < GridPriceInLaterHours or is there more behind it?