"Going solar allows us to have more control over our rates."
- Michael Glaze, general manager of South Feather Water & Power
San Rafael, California - July 23, 2004 [SolarAccess.com]
Summer time in Northern California used to mean people would plan when to water
the lawn according to times set by the water utility. But South Feather Water
and Power Agency wanted to give their customers more options for water use, so
they commissioned Sun Power & Geothermal Energy to design and install a 566
kW DC electric solar photovoltaic (PV) system that would cut back on the plants
reliance on the electric grid. The 2.2-acre solar system is situated on unused
land adjacent to the freshwater treatment plant, and it provides all the
electrical power for plant operations during the day.
The treatment plant runs all day, every day of the year. It will still use grid
power at night and on rainy days, but surplus energy produced by the PV system
on sunny days is automatically sent to the grid for credit with the California
utilities company Pacific Gas and Electric (PG&E) through net metering. The
combination of solar energy consumed by the treatment plant and utility credits
from PG&E should eliminate the agency's net annual electric bill completely
by 2024 when the system is due to be paid in full.
"Going solar allows us to have more control over our rates," said
Michael Glaze, general manager of South Feather Water & Power. "As
PG&E's rates go up, our ratepayers' water rates have to go up, too. I can't
imagine that a public agency would sit around and continue to pay an
ever-increasing electric bill. When they can have the power for less money,
doing nothing just does not make sense."
Energy costs are one of the largest expenses in running a water treatment
facility. In 2003 South Feather's electric bill exceeded US$ 160,000, and that
was up approximately 17 percent from 2002. The 566 kW PV system should generate
the equivalent energy needed to supply 200 homes. Having the on-site power
source removes South Feather's demand on the public utility grid and adds energy
to the grid during afternoon peak demand periods when California needs it the
most. The state has a shortfall of energy on hot summer afternoons when air
conditioning is in high use. This is also when solar produces the most energy.
The PV system includes 3,060 Sharp 185 W panels, two Xantrex PV225 inverters and
one Xantrex PV45 inverter. The arrays are tilted at a 22.5-degree angle to
collect the most sunlight during peak periods on summer afternoons at South
Feather's latitude. Because the silicon panels perform better when they are
cool, they are mounted on open steel supports to allow air to flow across the
top and bottom of the panels. For those extra hot California afternoons there is
a water misting system in the panel supports that turns on when the air
temperature reaches 90 degrees Fahrenheit (32 degrees Celsius). A separate water
spray system rinses dust off the top surface of the panels during dry periods to
keep them clean and productive. South Feather supplies water for the misting
system.
The total cost of the PV system was US$ 4 million, and the company received a $2
million rebate on the installation from the California Public Utilities
Commission.