Reliably harnessing that power is another matter. Even though the photovoltaic effect, where light energy produces electrical current, was discovered in 1839 by Edmond Becquerel, and the first practical solar panels were made in the 1950s, it wasn’t until the 2010s that technology had advanced enough for solar electricity to become competitive with fossil fuels. Parallel to this, the invention of lithium-ion batteries in the 1980s provided somewhere to store this energy.