Home Energy Management An Introduction to Solar Hot Water Systems—A.K.A. Solar Thermal

An Introduction to Solar Hot Water Systems—A.K.A. Solar Thermal


NATIONAL REPORT—An increasing number of solar thermal systems are being used by the hospitality industry. Almost every brand has invested in this technology to lower heating bills. These systems work in a wide variety of climates from southern Singapore to northern Denmark and throughout the United States.

What is a Solar Hot Water System?

Solar thermal systems are a proven technology that has been around since the early 1900s. However, the technology has greatly advanced. Today’s solar collectors are very efficient and have a lifespan of more than 25 years. Evacuated tube solar collectors are a popular choice for solar hot water systems and are dependable, efficient and cost effective.

Evacuated tube solar collectors function according to the same principle as the thermos bottle; the sun’s rays enter the tube and the heat remains trapped inside. The collector consists of a row of parallel transparent glass tubes that are connected to the collector’s manifold. Each tube contains a glass outer tube and metal absorber inner tube. The tube absorbs solar energy well, but inhibits radiative heat loss, so they work well in cold climates. When exposed to sunlight, the inside of the tube reaches very high temperatures (greater than 400°F).

Circulating fluid collects heat from the manifold at the top of the tube and is pumped to the heat storage tank, usually located in the building’s boiler room. Heat exchangers now transfer the heat to the building’s existing hot water system. By pre-heating the water, you reduce your fuel consumption.

Although evacuated tube technology has been around for 30 years, solar thermal technologies are just beginning to gain popularity in the United States. Today’s solar thermal systems are state-of-the-art. Efficiency is maximized through smart system design allowing full utilization of solar absorption and roof space. Overall efficiency of solar thermal systems is 73 percent, five times higher than photovoltaic systems. And this comes at a fraction of the cost.

Moreover, advanced monitoring systems instantly notify management of any drop in efficiency, allowing maintenance personnel to immediately respond and resolve any issue. These monitoring systems increase efficiency by providing for timely repair, minimizing loss of solar heat production. It should be noted however, that the efficiency of the system and the reliability of the monitoring system can be affected by the skill and experience of the solar installer. Therefore, it is important to use an installer who is well versed in system design and who incorporates the most advanced technologies in their systems.

The Benefits of Installing a Solar Hot Water System

Taking action to reduce emissions and realize financial benefits can give the hotel operator increased revenue and a competitive advantage. A green approach is also a great tool to increase the customer base and to engage employees.

Financial Benefits:

• Lower the hotel’s energy costs.
• There are many government incentives and financing options to offset upfront costs.
• Hedge against rising and volatile oil, natural gas and electric prices.
• Receive free hot water for the life of the system (25 years or more).
• High internal rate of return—typically 13 percent to 18 percent and payback periods of four to seven years depending on fuel costs.

Lower Risk:

• Remove uncertainty when budgeting for energy expenses—lock in energy costs.
• Turnkey system development.
• State-of-the-art monitoring systems provide detailed reports on system performance.
• Immediate servicing of the system if any efficiency losses are detected.

Marketing Advantages:

• Green branding builds public recognition as a sustainable energy leader.
• Green branding gets good press coverage.
• Green branding attracts customers to the facility.
• Reduced operating costs make the hotel more competitive.

Environmental Benefits:

• Reduce your facility’s carbon footprint.
• Reduce fossil fuel dependence and pollution associated with these fuels.

Social Benefits:

• Decreased reliance on foreign fuel sources that encourage U.S. relations with politically unstable countries.
• Reduced pollution in urban areas, which decreases the prevalence of childhood ailments, such as asthma.
• Improve your company’s image as a trend setter.
• Reduced demand for finite resources allowing existing fossil fuels sources to last longer.
• Play a part in creating local green jobs for skilled workers.
• Be a leader and promote the conversion to renewable energy.

Douglas Falkenburg is president of Ely Beach Solar, a solar thermal technology company specializing in installing and monitoring solar hot water systems in commercial buildings and multi-family residential developments. The company’s base is in New York City and surrounding counties.