Two thirds of all people who own a PV array generate enough electricity to become self-sufficient if they have access to storage, according to German utility E.ON. “66 percent of our clients with a solar array produce more electricity over the year than they consume,” the company’s head of German operations, Victoria Ossadnik, told broadcaster ntv. Using a home battery, owners can increase the share of self-generated electricity to around 70 percent. But E.ON said clients can become entirely self-sufficient by storing their power indefinitely using "virtual storage” already offered by the utility and several of its competitors. This “solar cloud” works similar to a bank account: People can fill it up with self-generated power, and withdraw it at a later date. “The further roll-out of decentral PV arrays is not only sustainable, but also efficient and could significantly speed up the transition to renewable energies,” Ossadnik said. Germany boasts more than 1.6 million PV arrays. If all 15.75 million homeowners installed a PV array on their roof, 20 million inhabitants could become self-sufficient using their green electricity, according to the article. Germany's rapidly rising share of weather-dependent renewable energy makes the country a test bed for storage technologies, to enable its use when there is no sun or wind. The technology has started to spread small-scale in the form of batteries, both in cars and homes – with large effects on power grids, utilities, and the countries supplying the necessary raw materials.