Solar Water Heating

Solar hot water is one of the most cost-effective ways to include renewable energy technologies into a home or commercial building.

It is a fact that a typical residential solar water-heating system can reduce the amount of conventional hot water heating by approximately two-thirds, which means that energy bills are also reduced. Solar water heating also reduces the impact on the environment that electricity and fossil fuel have.

If you think that solar water-heating systems are complicated pieces of machinery, they are not. In fact, many solar water-heating systems are comprised of two main components, the solar collector, and the storage tank. With the flat-plate collector, being the most common type of solar collector used for solar hot water systems. The storage tank is often larger and better insulated than a conventional hot water tank.

The heat from the sun is collected by the solar collectors, which either directly heats the water or a heat-transfer fluid in the collector. Once the water is heated it is then stored in the storage tank until it is needed. Many home use a conventional hot water system as a backup unit to provide additional heated water if necessary. Solar water heating systems are either active or passive, with the most common systems being active.

When a system is described as being active, this means that it uses electric pumps, and controllers to circulate water, or another heat-transfer fluid through the collectors.

The following is a brief description of the three common types of active solar water-heating systems:

1. Direct-circulation systems: These systems use pumps to circulate pressurized drinkable water directly through the collectors. Direct-circulation systems are not appropriate in areas where the temperature is below freezing for long periods or in areas that have hard or acidic water.

2. Indirect-circulation systems: These systems pump heat-transfer fluids through the collectors. Heat exchangers transfer the heat from the fluid to the clean, drinkable water. These systems can be used in colder climates as they use food-grade propylene glycol, which is non-toxic to keep the system from freezing as well as protect the system from over heating. This can occur when the load is low and the incoming solar radiation is high.

3. Drain back systems: These are indirect systems, which use pumps to circulate water through the collector loops that drain back into the reservoir tank once the pump stop. It is vital that drain back systems are carefully and correctly installed to guarantee that the water will completely drain from the piping.

Passive solar water heaters do not use any electrical components, but rely strictly on gravity and the fact that water will naturally circulate as it is heated to move the water through the collectors. Because these systems do not contain electrical components, they are often more reliable, easier to maintain, and have a longer lifetime than active systems.

The following is a brief description of the tow common types of passive solar water-heating systems:

1. Integral-collector storage systems: These systems consist of one or more storage tanks which are placed inside of an insulated box that has a glazed side facing the sun. Integral-collector storage systems are appropriate for moderate climates where temperatures seldom fall below freezing. These systems work well in most households where their hot water usage is primarily during the daytime and evening. These systems do not work well in households that have hot water usage primary during the morning draws as the system loses most of its energy overnight.

2. Thermosiphon systems: These systems are both economical and reliable as they rely on the natural convection of the warm water to circulate the water through the collectors and to the storage tank. The heated water in the solar collector rises naturally into the tank located above the collectors, while the cooler water flows down the pipes located at the bottom of the collector. Many manufacturers and installers of thermosiphon systems place the storage tank inside the attic so that it will be concealed view.

A solar hot water system can supply approximately 80-90% of an average household's water heating needs, which will reduce energy cost by approximately 1/3 or more depending on the system. Therefore, a solar hot water system is not only good for the environment, but it also makes a smart investment.

Home: DIY Solar Energy Systems

Solar-Powered Fans

Solar Water Heating

Disclaimer & policies