Forums

UK Hours to Charge from Grid

UK Hours to Charge from Grid

In UK, how may hours does it take to fully charge a Powerwall 2 from the grid, please?

sashton | December 4, 2018

There are many factors which will affect the charge rate and consequently the time taken to fully charge.
Recent firmware changes appear to have increased the charge rate.

Low ambient temperatures may reduce the charge rate.

On the current firmware (1.28.0), using the "cost saving" setting and no G83/3 restrictions it appears that the battery will charge at about 3.4 kW. Over the last few days my PW has taken about 4.25 hours to fully charge flowing the E7 off-peak rate.

While it is possible for the inverter to charge at 5kW it appears to throttled in this scenario.

sashton | December 4, 2018

*following* the start of the E7 off-peak rate - damn you spell-check!

peter | December 7, 2018

I have a G59 system (the installer wizard seemed to say 21A instead of 16A - but I only thought that's the export limit), installed today, with 2 PWs so will be interesting to see as I only have 4 hours of cheap power on Octopus Go each night. Depending on how long until Tesla approve my install (sounds like nonsense to me) I will see soon.

sashton | December 8, 2018

It's not really Tesla approving your installation but the DNO approving the connection of your equipment to the grid. Procedurally if you opt for the G83 setup you can apply for permission after installation. For G59 and you need permission beforehand. Usually the DNO will give you two figures, the total generation capacity and the export capacity of the site. The actual limits vary based on many factors:-

The LV connection to your site.
Any other generators sharing your LV connection.
The HV transformer upstream.
Any other grid considerations.

..so for example if you have an unshared 100kVA PMT and you LV connection is up to spec they will probably permit a generation capacity of about 23kW with export limitation at around 17kW. Depending on your DNO, they may want your export limitation tested to demonstrate that it fails safe.
If you're in a more urban environment the calculations will be more complex.

Sadly it is also a moving feast, with time based restrictions potentially on the horizon so it is even more imperative you obtain the correct permissions before installation or you could end up facing an expensive network reinforcement bill.