Storage systems collect and release energy at different times aiming at reducing energy use and supporting renewable energy systems. The integration of such systems at building level has to rely on small scale storage systems to better adapt to the building demand.

Small scale storage captures energy when the conditions are more appropriated due to optimal weather conditions such as high solar radiation or wind, low cost of energy or similar conditions. The energy storage will be released when demand is high and/or the release of the storage energy is more convenient than covering the demand with the existing generation technologies.

Energy storage involves the conversion of the produced energy form into a more conveniently or economically storable forms. The most used forms of storage are electrical and thermal storage.