Solar Water Heaters use insulated water storage tanks and solar collectors to generate hot water for your home or business.  Solar storage tanks have an additional inlet and outlet to connect to a conventional electric hot water heater as a backup for cloudy days and heavy use.  Solar water heaters are a cost effective way to use solar energy in your house or business.  Energy from the sun pre-heats water so your water heater can do less work.  Consult a local professional solar provider to help you size and price a system for your needs.

Active solar water heaters use pumps to circulate the water or transfer fluid through the system.  Direct systems can only be used in areas where it rarely freezes because water is pumped directly through the system.  Indirect systems can be used in colder climates because it pumps a propylene glycol anti-freeze transfer fluid through the collectors into a heat exchanger instead of water.  A wrap around heat exchanger heats the water inside the tank.  This process uses fluid forced convection to heat the cold water supply from about 50 degrees F to 130 degress F using a pressurized solar loop running at about 15 psi.  Propylene glycol will turn into glycol when stagnated at over 400 degrees F.

Passive solar water heaters are less expensive than active systems but they are less efficient.  They also will last longer and require less maintenance.  Integral collector storage systems work by allowing cold water to flow through the collector on the roof.  Hot water is drawn from the top of the system and replaced by cold water at the bottom.  It is the most basic system but will not work in areas with freezing temperatures.  Thermo-syphon systems involve installing the solar collector below an elevated insulated water storage tank.  As the water heats up in the collector it rises to the storage tank. 

Most domestic hot water uses for single family houses require increased loads from 6 AM - 9 AM and 6 PM - 10 PM.  The middle of the day when the water is being heated has low loads because most people are away from home at work or school.  Insulated storage tanks allow you to save hot water for uses at later times.  Apartment buildings have more constant hot water loads.  Industrial and commercial locations use loads during daylight hours while the systems are active.