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Photovoltaic
Cells
Environmental Mission > LEED
Gold Welcoming Center > Energy
Conservation
We have a 6.4 kW photovoltaic array installed on the roof of our Welcoming Center that produces approximately 9,000 kWh of energy per year, effectively reducing carbon dioxide emissions by about 8.5 tons annually, or the equivalent of 33,792 gallons of oil over 30 years. The cells are situated on a south-facing roof, designed specifically for this purpose, with additional room to expand the solar array in the future, as funds become available.
The solar cells on our roof are photovoltaic laminates (PVLs) provided by Uni-Solar. There are two general classifications of PV cells—crystalline silicon cells and thin-film cells. The PVLs on our roof are the second kind. Crystalline silicon cells are the most common type solar cells and typically have better efficiency than thin-film cells. However, thin-film cells use less than 1% of the raw material (silicon or other light absorbers) compared to traditional crystalline solar cells. Thin-film cells like the ones on our roof are also shadow tolerant, meaning if the cell is in partial shade, the rest of the cell—the part still in direct sunlight—continues to produce electricity, a characteristic that is not true of traditional crystalline cells. The PVLs are lightweight and flexible and come in long strips that are easily “installed” on the roof by simply pealing off the backing to expose an adhesive and sticking them on.
After the sunlight is collected with our PVLs, the DC voltage produced by
the array is converted to grid-compatible AC voltage and is then tied into
the grid. In case the solar panels do not produce enough energy to fully
power the building, then the additional necessary energy is drawn from the
grid. However, if there is a surplus of energy from the solar panels, the
excess energy is fed into the local grid and is available for use by other
consumers. By tying our solar panels into the grid, we ensure that every
single kilowatt-hour of energy produced by our solar panels is utilized,
and we help ease the load on the electricity company’s power systems
whenever possible.