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Solar panel and motor: Any way to regulate the power transmission?

I’m an engineering student and for an individual hobby-like project i purchased a small solar panel and a small solar motor. I am planning on making a small solar powered toy car. The question i have is: is there a way to connect a control or some other ways of regulating the power that is absorbed by the cells? Other wise the motor will just continue to run. Any answer would be greatly appreciated. Thanks!