It’s far from a mega-installation, but the 63 solar panels on the roof of the Prescott, Arizona, public library are likely to save the city (or county) almost $1,000 per month in electricity costs.
The $54,491 solar photovoltaic array, which became operational December 2, was made possible by the Prescott City Council, which approved the project on the basis of the library’s $7,000-per-month utility bill through Arizona Public Service Co., or APS, which is owned by Pinnacle West. The actual funding for the solar project came from the Yavapai County Library District property tax revenue.
The high cost of electricity for the library is largely due to the fact that it remains open every day of the week, and the costs support not only lighting and computer terminals but heating and cooling as well.
In the first two days of operation, library officials note, the solar photovoltaic array produced enough electricity to operate 480 light bulbs or 158 computers. The 158 computer terminals alone are astonishing. Most branch libraries have six or eight.
The system was installed by EV Solar Products of Chino Valley, which placed the winning bid, and the 8.2-kilowatt system, large enough to power a small mansion, is expected to produce about 18,000 kilowatt-hours per year. The average American home uses about 12,000 kilowatt-hours per year, though thrifty New Englanders survive on just under 10,000 kilowatts during the same period.
The system is monitored online, and interested parties can visit the site for information on daily, monthly or lifetime energy outputs, as well as peak outputs and the system’s overall status. On Sunday, Dec. 6, after 3 p.m., the system flatlined, but prior to that it had delivered 211.6 kilowatt hours for the month.
Nor is 8.2 kilowatts the end of the story. The current installation is viewed as a demonstration project, but residents can donate to a specially earmarked Friends of the Library fund to expand the system over time. According to library officials, every $1,000 received will add another photovoltaic panel and micro-inverter (to convert AC electricity to DC for use in the library’s electrical system, which is, of course, grid-tied).
When roof space runs out, the fund will have to be cancelled. In the meantime, the 8.2-kilowatt system ranks as one of the few (and one of the largest) solar systems on Arizona’s libraries, with the Ovonic installation at Red Mountain Branch Library in Mesa leading at 24 kilowatts.