An accurate tally of the world’s solar-power stations

REBUILDING AN ENTIRE planet’s energy system is a big job. Just ask the delegates at the COP-26 climate conference scheduled to kick off in Britain on October 31st. The most basic problem is knowing what, exactly, you are trying to rebuild. Academic-research groups, think-tanks, charities and other concerned organisations try to keep track of the world’s wind turbines, solar-power plants, fossil-fuelled power stations, cement factories and so on. To this end, they rely heavily on data from national governments and big companies, but these are often incomplete. The most comprehensive database covering American solar-power installations, for instance, is thought to miss around a fifth of the photovoltaic panels actually installed on the ground.