Basic solar system design

Selecting the right solar water heating system for a federal facility will depend on three key factors: climate, budget, and water usage needs. Solar water heating systems are economical, especially in commercial buildings where the energy used to heat water is significant. There are a number of technologies available to heat water efficiently. However, before implementing these technologies, it is important to first reduce hot water use with water-saving fixtures and appliances.

Solar water heating systems can be used throughout the United States on any building with a south-facing roof or unshaded grounds for installation of a collector. In addition, reliable off-the-shelf systems can be selected from the Directory of the Solar Rating and Certification Corporation.

The Arizona Solar Center Albuquerque, NM uses system sizing estimates based on climate:

• Sunbelt—use 1sq ft (0.09m2) of collector per 2 gal (7.61 L) of tank capacity (daily usage).
• Southeast and Mountain states—use 1 sq ft (0.09 m2) of collector per 1.5 gal (5.71 L) of tank capacity.
• Midwest and Atlantic states—use 1 sq ft (0.09 m2) of collector per 1.0 gal (3.79 L) of tank capacity.
• New England and the Northwest—use 1 sq ft (0.09 m2) of collector per 0.75 gal (2.81 L) of tank capacity.

Estimates will be affected by water temperature, consumption amount, and the solar resource available at the site.