Commercial Grid-Direct Photovoltaic System: Sierra Nevada Brewing Company

The Sierra Nevada Brewing Company’s system presented three major design challenges: accounting for multiple roof orientations, making a cost effective interconnection and minimizing roof penetrations.

Multiple roof surfaces and racking systems created ten distinct combinations of azimuth and roof tilt at the site. In order to maximize total system efficiency, multiple midsized inverters were used in place of larger inverters. The inverter manufacturer, Solectria, provided valuable design assistance. Each of the sixteen inverters was dedicated to a subarray with the same orientation. This will optimize production over the life of the system.

Interconnecting the system was not a big problem. Most of the design time was spent optimizing the interconnection around wire runs that average over 200 ft. in length. In order to make the interconnection as cost effective as possible, two separate PV system disconnects were used. One of these was located at a distance from the main revenue meter.This required close coordination with PG&E.

“Because 80% of the PV generating capacity was installed atop a membrane roof, we were very concerned about minimizing the total number of roof penetrations. The racking manufacturer helped address these concerns. SunLink uses a combination of penetrations, adhesions and ballast to structurally attach their tilt-up racking system. By specifying a 5° tilt and optimizing the design with SunLink engineers, we were able to limit the total number of roof penetrations. One penetration per every 10 to 15 modules was typical.” 

Rich Hawkins, Chico Electric

Overview:

DESIGNER: Rich Hawkins, Director, Solar Sales, Chico Electric, chicoelectric.com
LEAD INSTALLER: Bob Madison, Project Leader, Chico Electric
DATE COMMISSIONED: Phase 1 (~1 MW) February 2008 Phase 2 (~420 kW) July 2008
INSTALLATION TIMEFRAME: Phase 1, 4 months; Phase 2, 1 month
LOCATION: Chico, CA, 38.5° N
AVERAGE SOLAR RESOURCE: 5.5 kWh/m2/day
RECORD LOW TEMPERATURE: 19° F
ARRAY CAPACITY: 1.42 MW STC
AVERAGE ANNUAL AC PRODUCTION: 1,700 MWh

Equipment Specifications

MODULES: 7,648 Mitsubishi Electric PV-UD185MF5, 185W STC +3%/-3%, 7.58 Imp, 24.4 Vmp, 8.13 Isc, 30.6 Voc 
INVERTERS: 3-phase, 480 Vac system, 16 Solectria Inverters (4 PVI 60 kW; 7 PVI 82 kW; 5 PVI 95 kW), 600 Vdc maximum input, 330-500 Vdc MPPT range 
ARRAY: 16 modules per series string (2,960 W STC, 7.58 Imp, 390.4 Vmp, 8.13 Isc, 489.6 Voc), number of series strings per inverter varies 
ARRAY INSTALLATION: Membrane roof utilizes SunLink at 5° tilt to minimize roof penetrations; metal roof utilizes Unirac at 5° tilt; azimuth range between 160° and 190° 
ARRAY COMBINERS: Xantrex 10- circuit and 12-circuit combiner boxes, 12 A fuses 
SYSTEM MONITORING: Fat Spaniel Technologies

 

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