If you have a solar PV system and an electric vehicle (EV) and you charge your EV during the day when the sun is shining then it is obvious that you are using solar power to charge the car.
But what about if you charge at night?
By charging at night you might think that your EV is no longer solar powered. Strictly speaking this is probably true. Your solar PV system is not generating at night so it can’t be solar powered can it?
Well, it depends on how you look at it.
If you want to be completely accurate then no, charging your EV at night will not mean it is powered by solar power. How can it be? However, I look at it slightly differently.
I always charge my EV at night. Well, I say “always” but if I need to top up in the day to extend my range then I do but that is not very often. My normal, everyday, charging is always done at night and yet I claim that my EV is charged mostly from solar power and is therefore mostly CO2 free! How can I claim that?
The thing to remember here is that if you don’t use your own solar power at the time it is generated then it goes out to the grid. OK, you haven’t used your nice, clean, solar power but as it has gone to the grid and someone else has. Someone else that would have used normal grid power. So although you haven’t used it to charge your car, by sending that power to the grid you have reduced the CO2 footprint of the grid by the amount you generated, just as if you had used it yourself. The effect on the grid and on the environment is the same as if you had used it to charge your car with the solar power yourself.
Rather strangely, by charging at night there is a further good effect on CO2 generation. Consider for a moment those people that used your solar power that you sent to the grid. They would have used normal, daytime, grid power but instead they used your clean solar power. But you now charged your car at night and electricity generated at night is generally cleaner. So, effectively you have simply swapped their dirtier power used in the day for the cleaner power you used at night.
So, if you have solar PV, by using electricity at at night, the overall effect on the grid and on CO2 production is better than using power in the day… even if you have a solar PV system.
It seems strange to say that people that have a solar PV system should still use power at night but that is exactly what I am suggesting. Everyone, even if you do have a solar PV system, shift as much of their power use to the night if you want to reduce the CO2 generated.
As for my EV? Well, by generating solar power I am reducing the load on the grid by that amount regardless of whether it is me that uses it at the time it is generated or someone else so yes, I am saying my Nissan Leaf is almost totally solar powered and almost CO2 free.