Solar energy is now so cost-effective that, in the sunniest countries, it costs as little as £0.02 to produce one unit of power, making it cheaper than electricity generated from coal, gas or wind, according to a new study from the University of Surrey. The research team also found that the price of lithium-ion batteries has fallen by 89% since 2010, making solar-plus-storage systems as cost-effective as gas power plants. These hybrid setups, which combine solar panels with batteries, are now st...