Solar Water Heaters come in a variety of designs and mounting arrangements. Sun’s energy heats up the water using storage tank and collector.
Typical heaters are described as per the collector type and circulation system.
- Batch/Integrated Collector-Storage (ICS) systems- not recommended for cold climate as incompatible with closed-loop circulation system, they keep water in tubes within an insulated box. The water heats up and is released upon demand. The tempering valve serves to mix in cold water before delivering to the tap.
- Flat Plate – consist of copper tubes well-fitted to flat absorber plates. Common configuration comes with series of parallel tubes connected by two pipes i.e. inlet and outlet manifolds. The plate is contained in insulated box covered with tempered glass.
- Evacuated Tube collectors – most efficient collectors that work well in overcast conditions; operating as low as -40 degree Fahrenheit. Glass/Metal tubes contain water or heat transfer fluid is encompassed by larger glass tube. The vacuum between spaces results in minimal heat loss.
- Direct- water heated by sun in solar collectors get circulated through the system. The heated water stored in a tank is either used directly or sent to a tankless water heater. Works well in a climate where it rarely freezes.
- Indirect/Closed loop – use non-freezing liquid for heat transfer which passes through a heat exchanger in storage tank; thus heat reaches water and the fluid then moves back to collectors. Works well for freezing climates.
- Forced/Active – require electric pumps, controllers and valves to push the water through.
- Passive – this system requires no pumps but upon heating, natural convection transfers water from the collector to storage tank.