charge_tracker: Add PV and grid power price option #429
Description
At the moment the charge_tracker only can be used with one global price. This is not true when using it with PV excess charging.
It would be nice to be able to enter two prices: One for the grid price and one for the PV power price.
When a car is charged the mix of PV and grid consumption needs to be calculated. It would also be nice that there is a summary which states that X kWh where charged from the grid and Y kWh where charged vom PV excess.