The study defines as toxic waste the spent fuel assemblies from nuclear plants and the solar panels themselves, which contain similar heavy metals and toxins as other electronics, such as computers and smartphones.

To make these calculations, EP estimated the total number of operational solar panels in 2016 and assumed they would all be retired in 25 years — the average lifespan of a solar panel. EP then estimated the total amount of spent nuclear fuel assemblies that would be generated over a 25 year period. EP then divided both estimates by the quantity of electricity they produced to come up with the waste per unit of energy measure.

While nuclear waste is contained in heavy drums and regularly monitored, solar waste outside of Europe today ends up in the larger global stream of electronic waste.

Solar panels contain toxic metals like lead, which can damage the nervous system, as well as cadmium, a known carcinogen. Both are known to leach out of existing e-waste dumps into drinking water supplies.

The deployment of solar has increased significantly in recent years in response to government subsidies and mandates. Global installed capacity more than doubled between 2012 and 2015.

In 2016, solar provided 1.3% of the world’s electricity, with 301 GW installed. Nuclear reactors provided 10% of the world’s electricity in the same year.

A recent report found that it would take 19 years for Toshiba Environmental Solutions to finish recycling all of the solar waste Japan produced by 2020. By 2034, the annual waste production will be 70 - 80 times larger than that of 2020.