For information on solar energy in local communities, visit the Cape
& Islands Energy Information Clearinghouse.
three main types of solar energy: photovoltaics, solar thermal heating,
and passive solar heating and daylighting.
Solar cells make electricity from sunlight. They are generally composed
of semiconducting material that releases electrons when sunlight hits
it. Individual PV cells can be connected together to make systems designed
to produce any amount of power, from one cell that can power a calculator
to a few panels that can power a house to huge, utility-scale arrays.
PV panels require almost no maintenance because they have no moving parts,
and most come with decades-long guarantees. While they are expensive to
install, they can pay for themselves based on saved energy costs.
University's Ell Student Center using PV to supplement its power
Solar Thermal Heating
Sunlight contains thermal (heat) energy. This energy can be used to heat
water, air, or a working fluid. Heated water and air are most often used
directly but can be used to power other energy systems. Working fluids are
used either as a way to transfer heat to water or air, or they are used
to drive turbine/generators to produce electricity. Solar thermal systems
are most often seen as black boxes on rooftops that heat water for use in
homes, but they also exist as large power plants that use hundreds of mirrors
to concentrate sunlight to produce electricity. Solar thermal domestic hot
water and pool heating systems can generate a rapid return on investment.
be designed to use sunlight as a source of heat. They have large windows
on the south side of the building and very few windows on the north. The
windows allow sunlight to come in and warm the interior of the building.
The most efficient designs have overhangs that allow the sunlight to shine
in during winter months, when it is lower in the sky, but block the sun
in the summer, when it is higher. Materials can be used for the walls and
floors inside the building that absorb the sunlight’s heat during
the day and slowly release it through the night.
Impact 2000 house uses building-integrated PV and solar thermal
plus passive solar.
Sunlight can also be used to meet lighting needs. Natural
daylighting cuts down on electricity use and, by decreasing reliance on
incandescent light bulbs that generate heat, can help reduce air conditioner
National Renewable Energy Laboratory