A review of available methods for seasonal storage of solar thermal energy in residential applications

There is generally agreement among the HVAC (Heating Ventilating and Air Conditioning) community that one of the main issues impeding solar thermal technologies from achieving their full potential for space heating and domestic hot water (DHW) production applications is the development of economically competitive and reliable means for seasonal storage of thermal energy. This is particularly true at high latitude locations, where seasonal variations of solar radiation are significant, and in cold climates, where seasonally varying space heating loads dominate residential energy consumption. This review presents the principal methods available for seasonal storage of solar thermal energy. It concentrates on residential scale systems, and particularly those currently used in practice which mostly store energy in the form of sensible heat. Some newer methods that exhibit promise, like chemical and latent storage, are also briefly discussed and pertinent reviews are referenced.