Electric water heating accounts for almost one-fourth of the total electricity used in a home. Water heating is probably the main reason for big electricity bills. Solar energy can considerably reduce electricity bills and installation of a renewable energy source can eventually be cash in your pocket once it is put to work and cost recovered by reduced energy bills. One of the best ways to use the sun’s rays as a renewable source is by converting sunlight to solar thermal energy.
Solar Water Heaters
Solar thermal energy is considered as one of the simplest and most economical ways to use solar energy for hot water, pool, and space heating applications. This can be done in individual homes by using the sun’s energy collected on solar panels from where the heat is transferred to water flowing in copper tubes. In colder regions, the solar thermal energy system helps to complement an existing gas or electric water heating system to reduce cost. In warmer or not too cold regions, the solar thermal energy system can be directly used for bathing and in swimming pools, reducing costs by hundred percent.
There are two basic solar systems for hot water – passive and active. The passive solar thermal energy system is based on energy which is drawn from the sun and then transferred to heat water for domestic use. This kind of system is only possible to use in warmer climates. The active solar system is suited for colder regions. This system uses a pump to push the water through the solar collector and into the home.
The active solar system can either be an open loop where the water is directly heated by the solar collector or a closed loop system where antifreeze or glycol mixture is heated before transferring its heat to the water by a heat exchanger. The drain back system is a popular closed loop active system. In this system the freeze proof design drains water back into a small holding tank when freezing temperatures occur.
The closed loop system is best suited for colder climates. This solar thermal energy system uses a solar collector, heat transfer liquid, circulating pump, differential temperature controllers, heat exchanger and a storage tank. The sun’s energy is captured by the solar collector which transfers heat to an anti-freezing liquid. The heated fluid is pumped into the home and transferred to the domestic water supply which is stored in a tank for later use.