A major issue with solar power is the fact that photovoltaic systems cannot operate without sunshine. To address the availability problem of solar energy, EU-funded researchers considered direct storage in the form of a clean fuel, hydrogen.
Hydrogen is a clean gas that when fed into fuel cells produces water. Fuel cells operate like batteries to generate electricity through a chemical reaction. There is no combustion involved and therefore, no emissions. Not surprisingly, hydrogen stood out as the energy source that can replace fossil fuels.
Further details: Saving up sun for a rainy day