Solar Thermal

Siting and Feasibility  |  Financing  |  Case Study  |  This is Just the Beginning...

Solar thermal systems can be used for hot water heating, space heating, space cooling, and pool water heating.

Solar thermal collectors directly absorb the sun’s radiation to heat water or antifreeze for use in multiple applications. Systems are either open or closed: open loop solar systems heat water as it is piped through a rooftop collector (these systems must be drained in the winter). Closed loop systems circulate antifreeze through the solar collector. The heat is then exchanged in a conventional water heater, heating system, or other application. Closed loop systems operate throughout winter months.

Solar thermal systems are classified as either active or passive. The water or fluid in a passive system moves by convection alone. Active systems circulate the system’s water or fluid using electricity.

The heated water or antifreeze can then be used to heat domestic hot water, provide hot water for hydronic heating systems, or radiant floor systems

Newer solar thermal technologies provide space cooling using solar irradiation.

Site Considerations

Solar thermal systems are especially well suited to heating water for buildings with a year-round demand, such as gymnasiums or cafeterias. Solar thermal systems must be installed on unobstructed rooves in good repair. Flat, south-facing rooves are best.

Finance

While there are no direct financial incentives available for solar thermal systems, many schools have still found them cost-effective alternatives to natural gas or oil-heated water systems. And with the constant increase in natural gas and heating oil prices, solar thermal systems will be more widely incorporated into campus design. Solar thermal systems are especially cost effective for buildings with year-round hot water demand but as the site considerations above demonstrate, solar thermal is an interesting technology for many heating and cooling situations.

Solar thermal systems are much more efficient than solar PV systems, so all viable solar sites should be evaluated for PV and/or thermal installations.

Case Study

Chicago’s Wright Community College recently installed a solar thermal system that produces 400 gallons of hot water daily for the campus. The school estimates that the installation will reduce its annual greenhouse gas emissions by 6 tons. The system’s six solar collectors are mounted as an awning on Wright’s science lab. Most hot water produced is used in the science building and in a nearby cafeteria. The solar thermal installation is one of many installations on campus that double as teaching tools in the Building Energy Technologies curriculum.

UMASS Lowell is currently in preliminary stages of evaluating a solar-thermal system to heat water for its pool in its Costello Gymnasium building.

 

This is Just the Beginning...

Here’s a brochure describing Cape Cod Community College’s Solar Thermal Technology Certificate course guide.  Open the pdf file.

The Sustainable Building Sourcebook has an informative entry on solar hot water, heating and cooling systems.

The Harvard Green Campus Initiative has published an overview of possible solar-thermal applications on their campus.