Solar thermal water heaters use the sun's radiation to heat water and are composed of thermal collectors, a storage tank, and a circulation loop. They can be used alone or in conjunction with a backup conventional water heating system.
How to install a solar thermal water heater
Solar water heaters utilize a solar collector, which absorbs the thermal energy of the sun's rays and transfers the heat to the water in the storage tank. There are several different types of solar water heaters. These include:
Active solar water heaters
Active solar hot water systems use solar panels outside the building to heat water or an antifreeze fluid such as glycol, which is then circulated through a heat exchanger made of copper or steel that transfers the heat to the water. The heated water is stored in an insulated water tank until it is used.
Direct (open-loop) systems
Active direct open-loop systems circulate water through a solar collector, which then transfers the collected heat to the storage tank.
Indirect (closed-loop) systems
Active closed-loop systems circulate a fluid other than water, such as antifreeze, through the collector, and are more popular in climates prone to colder weather.
Passive solar water heaters
Unlike active solar water heaters, which use a circulating pumps and temperature controls, passive solar water heaters do not have any moving parts. They are typically less expensive and may last longer than active systems, but may also be less efficient.
Installing your own solar thermal water heater can be somewhat technical, but if you love a good DIY challenge, check out these links for some guidance:
- DIY Network
- Mother Earth News - How To Build An Integral Passive Solar Water Heater
- Guy Marsden's Blog - Installing My Solar Domestic Hot Water Heating System
Find it! Solar water heaters
Before you buy
Solar water heaters can be quite pricey to install, costing upwards of $3,000 depending on the system type and the difficulty of installation. Solar water heaters work best in mild climates with lots of direct sunlight. In addition, installing a solar thermal water heater may require a permit to comply with local building codes, zoning ordinances, and subdivision covenants.
Solar thermal water heaters help you go green because…
- Solar thermal water heaters use the sun, not fuel, to heat your water, lowering your greenhouse gas emissions—while cutting your energy bills.
Installing a solar thermal water heater can save up to five times the energy used by an electric boiler, because boilers draw electricity from utility sources like coal, where a significant portion of the energy is lost to heat. They offer the largest energy savings using a renewable energy source—up to $2,200 over the course of the equipment's lifetime.While how much money you will save depends on a variety of factors, such as the amount of hot water used and the geographic location, installing a solar water heater should lower your water heating bills by as much as 50 to 80 percent.
Tax incentives
In the US, installing a solar thermal water heater may qualify you for tax incentives at the federal, state, or local levels. For detailed information, see these resources:
- American Council for an Energy-Efficiency Economy: Updates on potential energy legislation.
- Tax Incentives Assistance Project: Explains federal tax credits for energy efficiency.
- Alliance to Save Energy: Offers an index of energy efficiency programs by state.
- Database of State Incentives for Renewables & Efficiency: Provides information on state and federal incentives.
- Contact your utility provider for information on local offers.
