Solar water-heating provides some of the best return on investment of any alternative energy option. Operating a 240 Volt water-heater is a very inefficient use of electricity. With our abundance of sunlight here in Florida, solar thermal collection is the logical choice. As much as 15% of a typical residential electric bill can be saved in this way.
In an “Open Loop” solar water-heating system, the domestic water is circulated through the collector (panel) on the roof. Here in Southwest Florida, we can utilize these systems because it rarely, if ever, gets cold enough to freeze. Where temperatures are an issue, a “Closed Loop” system uses an anti-freeze solution to capture the thermal energy of the sun. This heated glycol exchanges the heat to the water inside the storage tank. For our purposes, we will concentrate on the operation of open systems.
The ideal configuration for Sarasota includes a large storage tank, a flat-panel thermal collector and a PV-powered circulation pump. While storage tanks have electric elements for backup, these elements will supply all the hot water a household requires. Simply put, when the sun is shining it supplies heat to the water and low-voltage electricity to the pump. Appropriately scaled, these systems work without external power sources.