The Economics of a Solar Water Heater
Solar Water heating systems cost more than a conventional hot water systems. but in the long run you will save a bunch of money depending on your usage.
How much money you will save depends on these.

• How much hot water you use
• How good your system’s perform
• Location and your solar resource
• Available financing and incentives
• The cost of conventional fuels (natural gas, oil, and electricity)
• The cost of the fuel you use for your backup water heating system, if you have one.

On average, if you install a solar water heater, your water heating bills should drop 50%–80%. Also, because the sun is free, you’re protected from future fuel shortages and price hikes.
If you’re building a new home or refinancing, the economics are even more attractive. Including the price of a solar water heater in a new 30-year mortgage usually amounts to between $13 and $20 per month. The federal income tax deduction for mortgage interest attributable to the solar system reduces that by about $3–$5 per month. So if your fuel savings are more than $15 per month, the solar investment is profitable immediately. On a monthly basis, you’re saving more than you’re paying.
Solar water heaters also called solar domestic hot water system.
can be a cost effective way to generate hot water for your home . they can be used in any climate and the fuel they use sunshine and its free.
how they work?
solar water heating systems include storage tanks and solar collectors. there are two types of solar water heating systems: active , which have circulating pumps and controls . and passive , which don’t.
Most solar water heaters require a well insulated storage tank. solar storage tanks have an additional outlet and inlet connected to and from the collector. in two tank systems, the solar water heater preheats water before it enters the conventional water heater. In one tank systems the back up heater is combined with the solar storage in one tank.

Three types of solar collectors are used for residential applications.

Flat-plate collector
Integral collector-storage systems.
Evacuated -tube solar collectors

There are two types of active solar water heating systems.

Direct circulation systems
indirect circulation systems.