About 3% of all US energy consumption is dedicated to the activity of heating water. Weather in industry or in the household, water must be heated for all sorts of necessary activities. Fortunately, solar water heating is the most efficient and cost effective of all of the solar technologies. Depending on what kind of system you use, solar water heating can be about 60% efficient. In its simplest form, solar water heating technology is the idea of exposing a water container to sunlight to heat the water up. But solar water heating systems range in complexity.

The basic types of solar water heating systems are:
1)    Passive
2)    Active
3)    Thermo Siphon

The differences between these systems consist in cost, complexity, efficiency, and maintenance.

Passive Solar Water heating Systems

Passive heating systems are characterized by very simple ingenuity. This system consists of a water tank that is painted black to absorb more heat from the sun’s rays. The water tank is then encased in a sealed wooden box with a big window facing south.  The box is completely sealed and insulated to trap the heat in. This system is the most inexpensive but also the most inefficient. It usually takes a while for the sun to fully heat up the tank. But it’s the perfect system for the do-it-yourself person.

Active Solar Water Heating Systems

This system is by far the most complex of all three. Most active water heating systems consist of various pumps, controls, and valves. The idea behind active solar heating systems is to pump water through these solar collectors on the roof for it to be heated. The water is then pumped back to a holding tank to be used by the household. Some systems have a solar powered pump to run the water through the collectors.
There are three types of active solar water heating systems: drain-down, drain-back, and closed loop antifreeze systems. Each of these systems varies in complexity and maintenance. Active water heating systems were designed to be used in very cold climates to prevent water from freezing. There is still a chance water may freeze in the pipes leading to and from the water tank, thus needing to be freeze protected. Because of the many parts to these systems, they require much maintenance and oversight.

The Thermo Siphon Solar Water Heating System

These systems consist of a large water storage tank mounted above a solar water collector. The water collector is exposed to the sun and is sealed and insulated so that the heat accumulates. Since the heated water is less dense than cold water, it starts to rise through pipes up to the storage tank above the collector. It’s a very simple yet ingenious system.

Because of the simplicity factor, most people today are more likely to go with a passive solar water heating unit. And if you really want to save money, you can even make your own. There’s a great manual on passive solar water heating systems created by the great passive solar technology pioneer David Bainbridge. It is incredibly concise and easy to read. Your home made solar water heater can be made from a combination of recycled materials and other things you can get at the hardware store. The best thing about David Bainbridge’s “The Integral Passive Solar Water Heater Book” is that it’s a free download!

Bookmark to: