The Best Residential Solar Hot Water Systems

Types of Collectors

• Solar water heaters come with different types of collector panels. The integral collector system has a tank or tube in an insulated box which serves as both a collector and a storage tank. Water passes into the tank where it is stored while being warmed by the sun, then goes directly into the hot water cylinder. The evacuated tube system has rows of glass tubes in which the water is heated and then transferred into a storage tank that feeds the cylinder.

Active and Passive Systems

• Active systems are the most efficient for household use, but are also more expensive to install. Active systems include Open Loop systems, which use a pump to circulate the water through the solar collector panels and into the storage tank or cylinder, Closed Loop systems pump heat-transfer liquids such as glycol through the collectors, transferring the heat from the glycol to the water by means of a heat exchanger. Drain Back systems circulate the water through the collector. after which it drains into the storage tank without assistance.

  Passive systems such as Batch heaters have integral collector panels through which fluids pass without using a pump. With the Thermosiphon system, the warmed water rises through natural convection into a separate storage tank while cooler water flows into the collector for warming.

Choosing a System

• Your choice of system depends on several factors. The first is the location of the system. It must be possible to install the collector panels on an unshaded, south-facing location on your property at a tilt angle of between 45 and 60 degrees.

  The second factor is that the region must get direct sunlight for an average of five hours a day for it to be effective.

  Third, consider the needs of your household. Identify the cost of your hot water requirements, and work out how long it will take for the system to pay for itself at a saving of 60 percent.

Cost

• Analysis conducted by the Florida Solar Energy Centre (FSEC) puts the costs for a household installation at between $1500 and $2000. Homeowners should also budget for maintenance costs, estimated to be $25 to $30 per year, mainly for having the system checked every three years.

Benefits

• The short-term benefits of installing a solar water system are the savings, once the system has paid for itself. In the long term, however, you will be protected against cost increases as well as fuel shortages that may affect the power supply. At the same time, you will be reducing pollution and helping to protect the environment.