– For a list of federal and state
incentives, consult the Database of
State Incentives for Renewables &
Efciency at www.dsireusa.org/.
• Market Factors—The feasibility of a
renewable energy project is affected by
the price of electricity, cost of the fuel
mix, transmission congestion, and
market regulation.
Which Type of Renewable
Energy is Best for You?
Three types of renewable energy are
considered in this fact sheet—solar, wind,
and biomass.
Solar—Solar-powered electrical
generation can be accomplished through
“photovoltaics” and through “solar
thermal” energy. Photovoltaics, the
world’s fastest-growing energy
technology, uses solar cells to convert
sunlight directly into electricity. Solar
thermal uses solar radiation to heat a
fluid. Typically, solar water heaters use
pumps to circulate fluid through heat-
absorbing solar thermal collectors.
Photovoltaics—When considering these
systems, decision-makers must answer
questions about mounting, orientation
and tracking, shading, weather, and
electrical interconnection with the utility.
• Mounting—Solar arrays may be
mounted on the ground, the roof, or
integrated into the building. A roof’s
ability to support weight and wind
loads must be determined before that
option is chosen.
• Orientation and Tracking—There
are “xed-tilt” systems and “tracking”
systems. In the Northern Hemisphere,
xed-tilt systems typically face
southward or toward the sky and are
oriented at an angle that optimizes
panel efciency or system size and
output. Some can be seasonally
adjusted.
Tracking panels follow the movement
of the sun throughout the day. These
systems, which usually are ground-
mounted, generally have a greater
power output per panel than xed-tilt
systems. However, they tend to take
up more land and upfront costs may be
higher.
• Shading—Shade produced by
surrounding objects, such as trees,
buildings, and other solar panels, can
greatly reduce efciency in many
systems. Placement that eliminates
shading makes solar power more
reliable and more economical.
• Weather—In climates with signicant
snow or ice, thought should be given to
how design alternatives affect, and are
affected by, accumulation.
• Electrical Interconnection—It is
important to determine whether a load/
utility side interconnection is available.
In some cases, such as where net
metering is permitted, a hospital can sell
excess power generated back to the grid.
Solar Thermal—Solar thermal systems
have many mounting, orientation,
shading, and weather issues similar to
those discussed in the previous section.
Others include:
• Solar thermal collector types should be
evaluated for their sensitivity to tilt
angle and ability to shed snow and ice.
• There are “at-plate” (glazed or
unglazed), “evacuated-tube,” and
“concentrating” collectors. Glazed
at-plate and evacuated-tube collectors
can achieve temperatures necessary for
a hospital’s domestic hot water or space
heating and are the types that would
most commonly be used.
• In climates with freezing temperatures,
solar thermal systems need freeze
protection.
• Solar thermal tanks vary greatly in size;
the space required to house them may
be a determining factor in deciding
their location.
Wind—Wind can be harnessed by
turbines to produce electricity through a
generator. Small-scale turbines can offer
2
RENEWABLE ENERGY FACT SHEET
Renewable Energy Resources
Wind
Biomass
Solar
These maps provide a view of where three renewable energy sources are located in the United States.
1
1. AdaptedfromNREL.Solar:http://www.nrel.gov/gis/solar.html;Wind:http://rredc.nrel.gov/wind/pubs/atlas/maps.html;Biomass:http://www.nrel.gov/gis/biomass.html.