At its most simple configuration, a solar water heater can be described as a garden hose allowed to lie in the Florida sun for a couple of hours.  The residual water left in the hose is heated to a level that equals the temperature of water coming out of the faucet in the kitchen sink.  From the most primitive to the most sophisticated systems, it’s a tribute to the ingenuity, creativity, and inventiveness of man to view the array of designs available today.......

For example, a Chinese farmer in Shaanxi Province mounted sixty-six (66) interconnected beer bottles on a board placed on the roof.  The system provides enough hot water for the three members of the family to shower every day; cost-negligible and the collection of the bottles probably highly enjoyable.  Climb the ladder to a highly sophisticated design, and the system will provide all the hot water you require but at a substantial cost.  A solar water heater that incorporates solar panels with all the ancillary equipment can cost 4000 to 7500 dollars.  Typical annual savings can be 200 to 300 dollars. 

The first step is to perform a solar site survey to determine if enough sun will reach the solar collector to make the project worthwhile.  Obstacles (trees and buildings) could block enough sunlight to make you consider an insulated water heater blanket as an alternative to a solar heater system.  Not near the cost savings, but a useful device.  Most locations receive enough sunlight to enable the system.  But less sun means more collectors.  More collectors mean a more expensive installation.

The most common solar water heater installation uses flat plate solar collectors as a heat source in an open loop system where potable water flows directly from the collectors to the existing water heater.  The collector uses a series of copper tubes fitted to a flat absorber plate in an insulated box covered with low iron tempered glass.    An open loop system represents the simplest solution where freezing is not a threat to the system.  Where freezing is a problem, a water/antifreeze mixture is used in a closed loop system. In closed loop systems the water is heated by contact with a coil of pipes heated by the hot water.  Cold water flows from the tank to the collector on the roof where it is heated and then returns to the tank.  Small, low energy pumps perform that chore.

Where freezing temperatures are not much of an issue, batch water heaters provide an easy solution to solar water heating.  They’ve been around for a hundred years.  This system combines the collector and storage tank into one unit.  The water tank is enclosed in an insulated box covered with glass.  Cold water enters the bottom of the tank and hot water, taken from the top of the tank, flows into the existing water heater.  Batch water heaters installed on the roof, when filled with water, can weigh more than 320 pounds; therefore, roof integrity becomes an issue. 

After you decide on the appropriate system, the critical factor influencing an installation must include the time it will take to recover your investment.  There is one more factor, and it can’t be quantified.  How deeply are you committed to conserving energy?