If you have a smart meter you can see the charging kWHr rate. If you have the new Cooper SE and a 7kW chargepoint, make sure you change the charging current within the car's charging menu. We had to set our our car to charge at 7kW as the default setting is lower.
It's under My Mini, Plan Charging/Climate Control, Settings Charging Current.
Its not 100% straight forward as there are communication pins in the EV charge socket that allow the charging current to be altered- I have a combination of solar and mains, and the current will vary depending on the excess being generated by the panels. You cant do this by changing the input voltage, so its set buy the charge controllers. On the fast charge cable low is about 3.5 kw minimum and in my case 7kw on max due to the size of the mains input cable size in an external garage. It will go up when the PV panels are in full sunlight. On the mains cable its about 2.5kw on max, 1.5kw on reduced and 1kw on low