Catching Sunlight

Every hour, enough sunlight hits Earth to power all of human civilisation for an entire year. The problem was never energy supply — it was figuring out how to catch it.

The word photovoltaic literally means light-voltage. The effect was first observed in 1839 by Edmond Becquerel, a 19-year-old French physicist experimenting with metal electrodes in solution. It took over a century before anyone built a practical solar cell.