The batch heater, sometimes called the breadbox, combines the functions of collecting and storing heat inside one unit. This simple, direct connect, SHW system has been around for over 100 years and has become popular in desert areas where there’s a plentiful supply of sunlight and temperatures above freezing. The batch heater is classified as an ICS (integrated collector storage) It’s basically a tank of water, inside an insulated, foil-faced box, lined with insulation, covered with a glazing material and connected directly to a domestic hot water tank. Commercial batch heaters can weigh over 300 pounds when filled with water so they must be carefully supported when installed on a roof. Because of the weight as well as other factors the batch heater is often ground mounted and fed directly into a fossil fuel hot water tank. Above 50*F batch heaters work fine, but when Jack Frost comes a knocking batch heaters must be drained.