There are often circumstances in which thermal energy from the sun can be used directly for commercial and industrial uses. One example is heating water for use in industrial processing at Culligan Water Conditioning (CWC) in Danville Kentucky.

CWC has a de-ionization plant for regenerating spent ion exchange resins. These resins are used in portable de-ionization tanks used by manufacturing companies, laboratories, and hospitals to furnish pure water. The alkaline chemical mixture used for regenerating the anion exchange resin must be formulated using hot water. This hot water is being regenerated with the aid of Solar Collectors on the roof of the building. These solar collectors act as heat exchangers and heat water, directly, by conductance. The controller for the system can utilize a single Solar Panel to furnish electrical power for its operation.

Because the de-ionization process is used year-round, the Hot Water Tank has an electrical backup heater and also an electrical heater, in line.

The schematic flow diagram for such a system is given below.