I don't know. I've never been asked that question. We can have regenerative braking, but I think all other means of battery recharging are prohibited during competition. I will need to look through the rules and see.

FYI - There used to be an event called Solar Bike Rayce (sic) where solar panels and human power were used as supplemental power to the batteries. Their race lasted 3 hours. It was a really interesting event and a tremendous challenge, but for some reason it disappeared about 10 or 12 years ago.