Solar Thermal Water Heating Systems use the sun's energy to heat water for use by homes, commercial buildings and swimming pools. While some solar collectors look like solar photovoltaic panels, they are quite different. Solar thermal panels do not generate electricity, but simply absorb sun's heat.
Solar water-heating systems are designed to provide large quantities of hot water for residential and commercial buildings. A typical system includes several components:
The solar collectors absorb sunlight to collect heat. There are three types of solar collectors:
|An evacuated-tube collector is a set of many double-walled, glass tubes and reflectors to heat the fluid inside the tubes. A vacuum between the two walls insulates the inner tube, retaining the heat.||
The collector consists of a thin, flat, rectangular box with a transparent cover that faces the sun. Small tubes run through the box and carry the fluid — either water or some other fluid, such as an antifreeze solution — to be heated.
The tubes are attached to an absorber plate, which is painted black to absorb the heat. As heat builds up in the collector, it heats the fluid passing through the tubes.
While they look like solar photovoltaic panels, they are very different. Solar collectors do not product electricity, just absorb heat from the sun.
|It is the most powerful type of collector which concentrates sunlight at a single, focal point via a parabolic dish made of reflective surface.|
|More expensive||Least expensive||Most expensive|
|Highly efficient||Less efficient||Most efficient|
|Well suited to installation in cold, northern climates||Well suited to Southern installations with lots of sunlight|
|Best for installations with high demand for hot water and/or space heating||Well suited for applications that require large quantities of hot water and / or space heating|
|Very durable, but can be damaged by hail||Highly durable - less likely to be damaged by hail||Very durable|
|Easy to repair - individual tubes can be replaced|
|May be installed on a tracker - i.e., follow the sun during the day - to maximize efficiency|
Used in closed-loop systems to transfer the heat from roof liquid to water without the liquids mixing.
The storage tank holds the hot water. The tank can be a modified water heater, but it is usually larger and very well-insulated. Systems that use fluids other than water usually heat the water by passing it through a coil of tubing in the tank, which is full of hot fluid.
Used by system owners to measure and track system performance. While installing a monitoring device and service will add to the overall cost of your system, it will almost certainly pay for itself by:
Solar water heating systems can be either active or passive, but the most common are active systems. Active systems rely on pumps to move the liquid between the collector and the storage tank, while passive systems rely on gravity and the tendency for water to naturally circulate as it is heated.
Active systems come in two types:
Swimming pool systems are simpler. The pool's filter pump is used to pump the water through a solar collector, which is usually made of black plastic or rubber. And of course, the pool is used to store the hot water.