Electricity from renewable sources may be fairly cheap to make, but it cannot be stored and produced when needed. But the solar industry is moving to solve both problems with a single approach: gather heat from the sun, boil water into steam, spin a turbine and make power. Solar power, the holy grail of renewable energy, has always faced the problem of how to store the energy captured from the sun's rays so that demand for electricity can be met at night or whenever the sun is not shining.