I worked at a startup and designed the thermal battery and pumping systems for a solar powered milk chiller/storage system for the Indian market. About 500L of

I worked at a startup and designed the thermal battery and pumping systems for a solar powered milk chiller/storage system for the Indian market. About 500L of milk chilling & cold storage capacity, also storing solar energy as cold (not ice) Depending on where you are, you need a whole bunch of insulation to not condense vapor on the outside of your storage, because condensation is a killer for efficiency. My system needed about 50mm of foam rubber for the worst case, around a 1000L thermal storage medium tank, which makes these systems very large.