Why is my car not charging on solar only?

Limitations of the IEC 61851-1 standard

The standardised communication protocol between the EV and charging station (IEC 61851-1) defined a minimum charging current of 6 A before an EV is allowed to start charging. This means that there is a minimum required power before your vehicle can start charging. In case of a single phase installation this is 1.4 kW and 4.1 kW for a three phase installation. This is quite a large consumption for a PV installation and unfortunately we cannot change this. 


Workarounds to optimise for solar consumption:

1) Smart charging schedules

In this scenario we will optimise the consumption of your solar production throughout the day. This means we will import additional power from the grid, if necessary, to allow your vehicle to charge. A downside of this method is that additional solar production will not flow into the vehicle once the charging schedule has finished.


2) Adapting your charging cable

Another possible workaround is to detach 2 phases in a three phase installation. Our recommended approach is to detach the desired phases from the charging cable as depicted in the picture below.image.png

This decreases the minimum required power to 6 A * 230 V * # connected phases. Decreasing this required power increases the likelihood that you have enough solar production to start charging your car. A drawback of this approach is that you decrease the maximum charging speed of your vehicle. In most cases this is actually negligible because most EVs are only able to charge 16 A on 3 fases (11 kW) while they can still charge 32 A on a single fase (7.3 kW).