The Apollo Roof Top Units are suitable for installations on the roof of single homes. The flat-plates appear on the roof of your home nicely like skylights installed. The hot water storage tanks are usually installed in your basement, garage or anywhere you like. Coil heat exchangers are pre-installed inside the hot water storage tanks for using the solar energy to heat up cold water. Auxiliary electric heaters are also pre-installed in the hot water tanks incase of bad weathers and are switched on automatically by our intelligent controller or by yourself at your choices.