Solar Power Hot Water

Introductionand motels, restaurants and swimming pools. The
Solar water heating systems use sunlight to heatadvantages of solar water heating systems are
water. Solar energy is a pollution free and richthe following:
energy resource that can be used to complementÂ- Reduces 80 to 95% of the water heating bill
many of your energy requirements. Solar energyÂ- Reduces your energy bill
can be used as a form of heat as in the case ofÂ- It is environmental friendly and pollution free
solar water heating.Â- Reduces greenhouse emissions by minimizing
Solar water heating systems are a combination ofthe use of electric or gas water heater
solar thermal collectors, a fluid system to passÂ- Qualifies for the 30% federal tax credit
the heat from the collector to the point of use,Â- Doubles the amount of hot water available
and a tank to store heat for later use. TheSelecting a Solar Water Heater
systems can be used to heat water for domesticIn the United States the typical hot water usage
or business consumption, for swimming pools,is 15 to 30 gallons per person everyday for home
under floor heating, energy source for spaceuse. The typical water tank is sized to store a
heating and cooling and industrial uses.day's worth of use. So for a family with four
When placed in low latitudes areas (below 40members you could use an 80 gallon tank for
degrees), solar water heating system can supplyeveryday water requirements of 20 gallons a
around 60 to 70% of domestic hot waterperson per day.
consumption with temperatures up to 60 °C.So when choosing a system you should first
The most frequently used types of solar wateranalyze if freeze protection is required. If the
heaters are evacuated tube collectors (44%),place you live is freeze-free, a batch heater or a
glazed flat plate collectors usually used forthermosiphon unit is sufficient. If you have larger
domestic hot water (34%) and unglazed plasticneeds, go in for open loop direct pump system
collectors largely used to heat swimming poolscirculating water from storage tank to flat plat
(21%).collector. If freeze protection is required or the
Solar water heating systems are one of the mostwater is hard, you can go in for drain back or
cost-effective utilization of solar energy whichclosed loop systems with antifreeze and a heat
supplies hot water for domestic use. Each year,exchanger.
more than a few thousands of solar waterThere are different types of solar water heating
heaters are being installed all over the world.models and systems available. When purchasing
How it worksand installing a solar water heating system you
To use solar energy to heat water, a collectorneed to do the following:
needs to be fastened to the top of a building orÂ- Consider the cost of a solar water heating
on a wall which faces the sun. Collectors could alsosystem
be free-standing. There are two types of solarÂ- Assess your location's solar resource
water heating systems; active that has circulatingÂ- Find the right system size
pumps and controls and passive that is driven byÂ- Find out the system's energy efficiency
natural convection.Â- Estimate and compare system costs
The collector can be made of a set of metalÂ- Find out local conventions and regulations.
tubes surrounded by an evacuated glass cylinderInstallation and maintenance costs
or a glass covered insulated box with a flat solarFor installing solar heaters one has to take into
absorber made of metal sheet which is attachedaccount the solar resource, climate, your building
to copper pipes and painted black. A solar watercode and safety considerations. After the
heating system pumps cold water required to beinstallation it is required to maintain your system
heated to a collector and the hot water flowswell. Passive systems do not need much
back to a collection tank. This type of system canmaintenance. In active systems the plumbing and
supply adequate hot water for an entire family.other usual water heating components require the
The working fluid for the absorber could hotusual maintenance as regular systems.
water from the tank but usually it is a separateMaintenance is required for every 3-5 years and
loop of fluid which has anti-freeze and a corrosionthe ones with electrical components need to have
inhibitor which provides heat to the tank through acertain parts replaced after 10 years.
heat exchanger. Another method is theThe initial costs of a solar system if financed and
'drain-back' which does not require anti-freeze.evaluated with energy costs, then the monthly
Here the piping is sloped so that water is drainedcost of solar heat will work out cheaper than
drain back to the tank. The tank is open tomost regular hot water heaters. Also, the federal
atmospheric pressure. When the pump is switchedand local incentives are high.
off, the water flow is reversed and the pipesSumming up
drain off before freezing occurs.Solar water heating systems are a highly
Central heating is required at night when there iscost-effective way to produce hot water for
no sunlight and in the winter when sunlight isyour house. They produce hot water in almost
limited. Water in the collector could result in highclimatic conditions and the only fuel they use is
temperatures when the sunlight is good or if thesunlight which is available free of charge.
pump fails. So it becomes important to haveThe total installed capacity of solar water heating
designs that take into account to provide relief ofsystems as of 2007 is around 154 GW. China
pressure and excess heat with the help of a heatleads in the utilization of solar water heating
dump.systems with installed capacity of 70 GW as of
Benefits2006 and a plan to achieve 210 GW by 2020.
United States expends more than $13 billion everyIsrael leads in the per capita usage of solar water
year on energy for domestic water heating. Itheating systems with almost 90% of homes
equals to almost 11.4 barrels of oil per household.using this system. In the United States, Canada
Solar water heating systems reduces the fueland Australia, solar water heating systems are
needed to heat water as the system uses thelargely used to heat swimming pools with the
sun's renewable energy. Solar water heatinginstalled capacity of 18 GW as of 2005.
systems can also be used for car washes, hotels