Solar is the cheapest energy already. EV's are more efficient then gas cars. The charge time is a solved problem but the biggest problem is infrastructure and cost of new technology. We are optimised for gas, and coal. we will burn that shit up if we don't regulate it or invest heavily. We will always need oil for plastics and as lubricants but we could stop burning it within the next 20 years if we make regulations. In fact, the EU passed a bill that stops the selling of gas Cars in 2035. I don't think this will work but I hope it helps fast forward the process