The Fayetteville Public Works Commission (PWC), which provides electric service to more than 87,000 customers and is the largest public power provider in North Carolina, recently completed the state’s first municipal community solar and energy storage farm. The installation provides enough energy to support the equivalent of 100 homes and is available to Fayetteville PWC customers as a shared re- newable energy option. Providing Customers with a Renewable Resource While solar is becoming an increasingly appealing option to environmentally conscious homeowners, many residences are not suitable for the installation of panels. Older roofs, shaded roofs, or those lacking a south-facing orientation may be barriers to installation, as well as up-front costs and on- going maintenance requirements. Many customers also rent their homes, preventing them from installing solar panels. The Fayetteville PWC Community Solar Program is a large- scale, ground-mount solar array that enables residents to benefit from municipal solar through a monthly subscription service. Eligible customers may subscribe to a maximum of five panels for a period of up to 25 years. The Fayetteville PWC selected Dewberry as general contrac- tor for the turnkey, design-build project. The system consists of a nominal one megawatt alternating current (MWAC) per 1.2 megawatt direct current (MWDC) solar photovoltaic array, with a nominal 500 kilowatt direct current (kWDC) lithium-ion battery bank along with wiring, inverters, and controls. The use of string inverters, which convert the 12- volt DC power produced by the solar array into useable 120- volt AC power, together with a mini-battery storage system, allowed for a significantly reduced project footprint over standard, utility-scale inverter systems. Fayetteville Builds Community Solar Farm Cutting-Edge Technology Minimizes Project Footprint By Rick Jones, Ph.D., C.P.E.
The Fayetteville PWC’s Community Solar project is among fewer than a dozen in the country that feature strin
sonal/daytime variations in the angle of the sun. The combination of the solar array with the battery system enables the Fayetteville PWC to discharge battery power during peak demand, when buying wholesale power from Duke Power is the most expensive. The lithium-ion battery will store 1,120 kilowatt hours of electricity. The Fayetteville PWC estimates that the average residential customer uses 1017 kilowatt hours of electricity each month, with the potential for five solar panels to produce an average of 196 kilowatt hours per month, or approximately 19 percent of consumed energy. The energy generated from the panels is delivered directly to the grid and credited to subscribing customers.
The string inverters are housed in two-foot by two-foot containers placed every three rows among the panels, with the entire array span- ning approximately six acres. The battery storage system and controls are sited on a concrete pad measuring approximately 30 feet by 15 feet, and the cabling and conduits are run underground. The ground-mounted array consists of 3,384 Tallmax 72-cell multi- crystalline 330-watt modules with a single-axis tracking system that features a two-hour battery discharge capacity duration. Each solar panel produces an average of 39 kilowatt hours per month, or close to 470 kilowatt hours per year, subject to weather variations and sea-
10
csengineermag.com
April 2021
Made with FlippingBook Annual report