The
system consists of two 1.2KW sub-arrays (2.4KW total
capacity) each with its own grid-interactive inverter. The
output from both of these inverters is connected to a
Capitol electric service panel. The photovoltaic array is
mounted on fixed hardware and includes a grid-interactive
inverter that ties the array output to the electrical
service for the Capitol Building. The system, on the
southeast corner of the Boiler Plant Building, is highly
visible to several other state agencies, as well as from
Roberts Street. The building lies along the route of the
Montana Historical Society Tour Train, which serves
thousands of visitors each year, and the array will no doubt be
featured in the tour.
Designed and installed by Independent
Power Systems, Inc., of Bozeman, Montana, the system
faces south with a fixed tilt of approximately 45 degrees.
Estimated annual output of the system is 3,679 KWh. It is
expected to have a useful life of 20-plus years and should
require little maintenance other than periodic cleaning
of the array and tightening of electrical connections. The General
Services Division will maintain the system and will log
the power output on a monthly basis over a period of two
years.
Major system components include:
- photovoltaic modules with a combined total output of
2.4KW
- array mounting structure, ballasted pan type
- fused disconnects, lightning protection system, and
miscellaneous electrical components
- grid-interactive inverter with system monitoring
capability
Total installed system cost was $32,068. Estimated
electric cost savings from the project: $343/year.
Project funding came from Montana Power Company's Universal
System Benefits fund ($26,522) and the State Department
of Environmental Quality funds ($5,546). The project was
installed in October 2001.
