Joule Energy Old Alabama Road 2 solar project

Overview

PROJECT TEAM: EPC—Joule Energy, joule-energy.com; owner—Boviet Solar USA, bovietsolarusa.com; developer— Hecate Energy, hecateenergy.com

DESIGN & INSTALLATION LEAD:

Corey Shalanski, senior PV engineer, Joule Energy

DATE COMMISSIONED: April 2017 INSTALLATION TIME FRAME: 40 days LOCATION: Woodland, GA 32.8°N SOLAR RESOURCE: 4.59 kWh/m2/ day

ASHRAE DESIGN TEMPERATURES:

95°F 2% average high, 12.2°F extreme minimum

ARRAY CAPACITY: 1.613 MWdc

ANNUAL AC PRODUCTION: 2,826 MWh

Located in Woodland, Georgia, the Old Alabama Road 2 (OAR 2) solar project

represents two trends present in many megawatt-scale ground-mounted PV installations—tracked arrays and the use of string inverters for power processing. The OAR 2 project team has three primary stakeholders: Boviet Solar, a subsidiary

of Powerway Group, is the system owner and module vendor; Hecate Energy served as the project developer; and New Orleans–based Joule Energy was the proj- ect EPC firm.

Site grading began in late September 2016. Construction coincided with

a significant drought that impacted much of western Georgia, and the drought conditions complicated early construction efforts. At one point in

the site preparation process, the grad- ing contractor was not able to secure burn permits. As a result, workers had  to truck vegetation debris off-site, which added unanticipated cost and resulted in a minor project delay. Another early delay resulted from the severing of

an unmapped 2-inch gas line during stump excavation. Further investigation revealed that the pipe had been aban- doned and supposedly capped off many years ago. The project team worked with local officials to trace the source of the pipe and quickly and safely make the appropriate repairs.

With site preparation completed, Joule Energy opted to subcontract the tracker and module installation, focusing its efforts on realizing the cost 

savings that optimizing the ac power collec- tion system would offer. Considerations included the strategic location of power processing equipment and ac aggrega- tion panels, as well as approaches to minimize the project’s wiring material

cost and speed conductor deployment. A total of 35 Ginlong Solis 40 kW 3-phase string inverters provides power conver- sion and optimization for OAR 2.

All array rows contain even num- bers of tracker tables, which simplified the wiring plan. This configuration allowed Joule Energy to parallel two module source circuits and thereby minimize homerun wiring back to the string inverters. Joule developed a rela- tively simple homerun gauge scheme based on each string’s position in its row. For shorter runs, it used 10 AWG and 8 AWG conductors; for longer runs,it stepped conductor size up to 6 AWG. Installers paralleled strings using Y branch connectors for 10 AWG and 8 AWG conductors and Tyco GTAP con- nectors for 6 AWG conductors.

Equipment Specifications MODULES:  5,040   Boviet  Solar BVM6612P-320,  320  W  STC,  +5/-0  W,

8.65 Imp, 37 Vmp, 9.17 Isc, 45.5 Voc

INVERTERS: 3-phase 277/480 Vac

service, 35 Ginlong Technologies Solis-40K-US, 1,000 Vdc maximum input, 200 Vdc–800 Vdc MPPT range

ARRAY: 18 modules per source circuit (5,760 W STC, 8.65 Imp, 666 Vmp,

9.17 Isc, 819 Voc), eight source circuits per inverter (inverter 46.08 kW, 69.2 Imp, 666 Vmp, 73.36 Isc, 819

Voc), array total 1.613 MWdc

ARRAY INSTALLATION: GameChange Solar Genius Tracker, single axis, independent row, 90° standard rotational range (104° range option), Zigbee wireless network

INVERTER AGGREGATION PANELS:

Three 800 A panels with 800 A disconnects (two disconnects fused at 750 A and one fused at 700 A)

SYSTEM MONITORING: Locus Ene