About Solar Water Heating

Solar Water Heating Systems


Solar Water Heating has often been called the “low hanging fruit” for homeowner’s wishing to lower their energy bills.  Solar Water Heating Systems are a cost effect way to significantly reduce your energy bill before considering more costly technologies such as a solar electric system. An electric water heater is the most costly way to heat water, both to the pocketbook and to the environment.  Solar Water Heating Systems can save up to 25% of your electric bill and provide a rapid return on investment.  If you are considering installing a solar electric system, eliminating the load from your electric water heater can significantly reduce cost of installing solar electricity on your home and increase your return on investment.


Many homeowners also choose to replace natural gas water heaters with solar water heating systems with solar.  Although, not as cost-effective as replacing an electric water heater, if you need to replace your water heater soon, you can achieve a more rapid return on investment and avoid the creation of many tons of emissions over the life of the solar system.


A solar water heating system uses Arizona’s sunshine to provide hot water for your family. While installing a solar water heating system can cost more initially, with today’s incentives from utilities, the state and federal government, your return on investment can be as little as three years. This is especially true if your water heater is over 7 year old and may need to be replaced soon.


Properly used, a solar water heating system can provide the vast majority (95%) of your how water for free.  In fact, many homeowners who have installed solar water heating rarely turn on their backup element except for periods of extensive cloudy weather.


System Components


There are a number of basic components to a Solar Water Heating Systems.  A Solar Thermal Collector, sometimes called a flat plate collector collects energy from the sun.  A Solar Storage Tank, similar to your traditional water acts as a reservoir for your supply of hot water.  It also contains a backup element that will provide a backup supply of hot water for extended periods of cloudy days.  Experience has shown us that most families can obtain 100% of their hot water from the sun from March through early October.


Additional components include a pump, or pumps, depending on the type of system, a controller that tells your system when energy can be efficiently collected, and various other valves and plumbing components that have been carefully selected to provide for years of long lasting service.


Solar Collectors


Solar Thermal collectors, often called flat-plate collectors, are rectangular boxes covered with glass.  Generally, they come in two sizes, 4’ X 8’ (32 sq. ft.) or 4’ X10’ (40 sq. ft.) and are mounted on your roof facing south.   They contain a dark absorber plate which is the part that actually collects the suns energy and transfers it to water or a heat transfer fluid.   The collector is insulated and covered in glass to create a greenhouse effect and obtain extremely hot temperatures instead the collector to heat your water.


Unglazed flat-plate collectors are a dark absorber plate without any enclosure or glass cover.  They can be made of metal or a polymer material and are used in low temperature applications such as swimming pool heating.


Storage Tanks


Solar Water heating systems generally require a solar storage tank to provide for your hot water supply.  Most solar storage tanks are either 80 or 120 gallons in size.  This larger size provides you with enough storage to last into the night time when many families use hot water.


Solar storage tanks also generally contain a backup electrical element to provide hot water on cloudy days or in times of greater usage.  This backup element should be controlled either a timer or switch so that homeowner can keep the backup element off and obtain a greater portion of their hot water from solar.


In some cases, a solar water heating system will be installed as a two tank system.  In installations such as this, the solar storage tank feeds, or preheats, your existing water heart with solar heated water and provides an even grates supply.  This type of system is generally used for larger families.


Types of Systems


Active Systems


Active solar water heating systems use pumps to circulate water or a heat exchange fluid from the storage tank or the heat exchanger through the collectors.  There are two types of Active Systems, direct and Indirect Systems.  With a Direct System, water from the solar storage tank is pumped directly through the collector to be heated by the sun.  This type of system is used in climates where there are rarely nights that go below freezing.  Freeze protection is provided through the recirculation of water through the collector if the collector is in danger of freezing.


Indirect systems use pumps to circulate a heat transfer fluid through the collectors and into a heat exchanger.  Water is then pumped through the heat exchanger and into the tank.  Indirect systems are necessary in climates with freezing temperatures.


Passive Systems


Passive solar water heating system move water or a heat transfer fluid through the system without the use of pumps.  The two primary types of passive systems are the Thermosyphon system and the Integral Collector Storage ( ICS) system.


Thermosypohon systems work through the natural convection process of heated water.  With the tank mounted above the collector, hot water or the heat exchange fluid rises through the collector into the tank, displacing cooler water to the bottom of the collector.


The Integral Collector Storage (ICS ) system is composed of a number of large tubes inside a large collector box.  These tubes are plumbed in series and the hot water is fed into your existing water heater when you turn on the hot water tap in your home.   These systems should only be installed in warmer climates.


>> Guidelines to Purchasing a Solar Water Heating System

Important Links

>> Arizona HOA Statues

>> Solar Customers' Bill of Rights