Solar water heating systems comprises of storage tanks and solar collectors. Solar water heaters use the sun to heat either water or a heat-transfer fluid in the collector. Most solar water heaters need a well-covered storage tank. The tank can be a remodelled standard water heater, but it is generally larger and very well covered. Solar storage tanks have an extra outlet and vent connected to and from the collector. In two-tank systems, the solar water heater warm up water before it enters the conventional water heater. In one-tank systems, the back-up heater is merged with the solar storage in one tank.
Types of Solar Collectors:
Solar collectors collect the sun’s energy, alter its radiation into heat, and then alter that heat to water or solar fluid. Three types of solar collectors are used in solar water heating systems:
- Flat-Plate Collectors: A usual flat-plate collector is a covered metal box with a glass or plastic cover and a dark-coloured protected plate. Unglazed flat-plate collectors—usually used for solar pool heating—have a dark protection plate, made of metal or polymer, without a cover or assigned area.
· Integral Collector-Storage Systems: Integral collector-storage systems are made of one or more black tanks or tubes in a covered glazed box. Cold water first passes through the solar collector, which preheats the water, and then carries on with the conventional backup water heater.
· Evacuated-Tube Solar Collectors: Evacuated-tube collectors can attain very high temperatures, making them more suitable for cooling applications and lucrative and industrial application. The collectors are generally made of parallel rows of see-through glass tubes. Air is removed, or cleared, from the space between the two glass tubes to shape a vacuum, which removes conductive and convective heat loss.
Kinds of Solar Water Heating Systems: There are two types of solar water heating systems: active, which have flowing pumps and controls, and submissive, which don’t. Active Solar water Heating: There are two kinds of active solar water heating systems:· Direct Circulation Systems: Direct-circulation systems utilise pumps to flow pressurized edible water directly through the collectors. These systems are apt in areas that do not freeze for long periods and do not have hard or acidic water.
Indirect Circulation Systems: Indirect-circulation systems pump heat-change fluids through collectors. Heat exchangers transfer the heat from the fluid to the edible water. They are well known in climates vulnerable to freezing temperatures. Thermosyphon System: Thermosyphon systems depend on the natural convection of warm water mounting to flow water through the collectors and to the tank. As water in the solar collector heats, it becomes lucent and rises naturally into the tank above. For now, the cooler water flows down the pipes to the bottom of the collector, increasing the flow. Some manufacturers place the storage tank in the house’s roof, keeping out of sight from view. Indirect Thermosyphon can be installed in freeze-prone climates if the piping in the unconditioned space is sufficiently safeguarded. Backup System: Solar water heating systems almost always needs a backup system for cloudy days and times of enhancing demand. Conventional storage water heaters generally give backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with Thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collect solar energy, it may be packaged with a water heater for backup.