Now that we have solar (PV) panels and two electric cars there’s much more opportunity to take advantage of sunny days and charge a car from the sun.

Today is one of the first sunny days of 2018 when I’ve been able to do this. The panels supply, at most, 2.6kW around mid-day. The PodPoint charger can supply up to 7kW to our Ioniq, so clearly using this combination only at most a third of the electricity will be from our panels. The other possibilities are:

-Set the car to a lower charging rate (from the dashboard), down to 16A or 3.3kW (Ioniq)

-Charge the Leaf using the PodPoint as it draws 3.6kW maximum

-Use the “granny” charger to charge at up to 12A (Ioniq) or 10A (Leaf), around 2.4kW

-Set charge timers from the car, to set the start or end of charging periods.

Financially there’s a risk here, since if the sun goes in then I’ll be using mains electricity at around twice the price compared to charging overnight on off-peak rate!

Today I simply plugged the Leaf in using the “granny” charger plugged into a 13A plug. The forecast was for a sunny morning, Being summertime (daylight savings time) our off-peak runs until 8.30am, and so the first hour or so was off-peak rate anyway. As the sun rose in the sky the proportion of our own PV-generated power rose with it, until mid-day when the car was full anyhow – it wasn’t fully discharged.

OEM-050418

This graph is from our Open Energy Monitor (OEM). The blue is the whole house load, yellow the solar. In this case most of the blue area represents the Leaf charging, the bumps are fridges and other loads. Out of a total of 10.9kWh used, around 10kWh is the Leaf, and of that 6.8kWh is solar PV. So the Leaf was charged on 70% home-generated power, the rest was sourced from Octopus on a 100% renewable tariff.

The next step is of course to automate this, using an intelligent charger so that the charging power can follow the available solar PV generation, and take account of the more usual cloudy days with sunny intervals. There are commercial chargers that can do this job; it would be great if cars were fitted with chargers that can take a signal from a system like OEM’s, where the available home-generated power is broadcast on wi-fi. Alternatively a home battery would charge automatically to store the PV-generated power and could be used at any time to charge the car and/or run the other house loads. A few more solar panels wouldn’t go amiss either.

My Octopus solar energy referral – we could both get some cash when you move to a renewable tariff!  

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