Some observations on the Tesla Powerwall 2 battery system.
We’ve had this system installed since January and it’s been pretty impressive so far.
Nominal maximum storage is 13.7kWh and there’s a maximum discharge threshold you can set to hold power in reserve for a power cut. It seamlessly steps in during a power cut and maintains power for the whole house.
It monitors the weather and learns your usage patterns. For instance we set it to top up overnight on cheap off peak electricity and then the house runs on the battery and solar during the day. If the next day is forecast to be sunny it automatically reduces the amount it takes from the grid overnight, so for very dull days it loads up to 100% before morning and for bright tomorrow’s it takes no charge over night. So far it’s not made a mistake.
Since it was installed (in conjunction with our solar) we have consumed 1.8 MWh and 0.84 MWh has come from solar. As far as the grid is concerned we’ve only spent spent £11.10 on peak rate electricity during that period, the rest of grid consumption has been at 12p/kWh. Now the winter is behind us, I would expect any grid usage to drop dramatically.
Another feature of the Powerwall is “storm watch” where you can set it to automatically load up from the grid in anticipation of a storm, this is useful for us as we have a lot of trees and overhead power cables.
