An article in Science Daily talks about progress on smoothing out the intermittentcy problem of solar energy. They have a demonstrated solution that uses proven technology without exotic elements.
The approach taken by EPFL and CSEM researchers is to combine components that have already proven effective in industry in order to develop a robust and effective system. Their prototype is made up of three interconnected, new-generation, crystalline silicon solar cells attached to an electrolysis system that does not rely on rare metals. The device is able to convert solar energy into hydrogen at a rate of 14.2%, and has already been run for more than 100 hours straight under test conditions. In terms of performance, this is a world record for silicon solar cells and for hydrogen production without using rare metals. It also offers a high level of stability.The other side of the equation would be an efficient hydrogen-base fuel cell and there has been much recent progress on that front as well.