Project Profiles

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A federal mandate to Army base facilities nationwide to utilize on-site renewable energy generation set the stage for the Fort Hunter Liggett project in 2010. Phase One is composed of two 581 kW canopy array structures commissioned in April 2012. Robert A. Bothman, Inc., served as the project’s developer and general contractor, working directly with McCalmont Engineering, the Army Corps of Engineers, Pacific Gas and Electric Company (PG&E), Nuño Iron and InterMountain Electric during the project’s implementation. The base’s installation was one of the first US Department of Defense projects funded through the Energy Conservation Investment Program. All components were required to meet the Buy American provision of the ARRA.

The PV system is designed to meet the Army’s stringent requirements for electrical installations and went through numerous reviews and quality control checks. In many cases, the safety protocols, installation methods and materials exceeded those utilized in comparable civilian installations. For example, daily safety equipment checks were required prior to work commencement and rigid metallic conduit was required for all exposed conduits.

Phase One is located in the base’s logistic center, with two arrays that are 1,175 feet long by 45 feet wide. The array surface is elevated approximately 20 feet above grade. To accommodate the large vehicles to be parked under the array, the installed piers are spaced 28 feet apart to allow an adequate turning radius. Due to previous ground contamination issues at the site, the foundation design limited penetration depth to minimize soil disturbance.

Nuño Iron custom built the steel substructure supporting the Unirac ISYS mounting system to specifically match the racking. The structure’s welded tabs connect directly to the ISYS racking and require a tolerance of 7/16 inch over the approximately quarter-mile–long array structures. The project’s installation firm, InterMountain Electric, had up to 13 electricians on site at the peak of the installation, with multiple scissor lifts working in tandem to access the elevated array.

Two Advanced Energy Solaron 500 kW inverters, located on a single pad underneath one of the arrays, are connected directly to a dedicated 480 Vac–to–12.47 kVac transformer. This configuration allows for direct interconnection to the base’s medium-voltage distribution system via 1,500 feet of new underground conductors. An additional megawatt of system capacity will be deployed during Phase Two of the project. All electrical design and installation was planned in anticipation of the expansion.

The DECK Monitoring system tracks production and environmental data, and is configured to transmit alarms to site personnel if sections of the array are underperforming. The monitoring system connects to the Internet via a 3G wireless signal and broadband routers, and includes intrusion logging and reporting as well as denial service to mitigate any hacker attacks.

“Since this project was one of the first funded ECIP projects through the Army Corps of Engineers in Sacramento, there was tremendous political oversight. Local contractor and vendor participation was a highly valued aspect as well. Our solicitation and contracting of numerous local subcontractors and vendors was essential in completion of the project on time and on budget.

Brian Bothman, vice president, Robert A. Bothman, Inc.

Overview

PROJECT DEVELOPER: Robert A. Bothman, Inc., bothman.com
ELECTRICAL DESIGN FIRM: McCalmont Engineering, mccalmont.net
INSTALLATION FIRM: InterMountain Electric Company, im-electric.com
DATE COMMISSIONED: April 24, 2012
INSTALLATION TIME FRAME: 251 days
LOCATION: Jolon, CA, 36.0°N
SOLAR RESOURCE: 5.8 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per Solar ABCs solar reference map: 100°F/21°F
ARRAY CAPACITY: 1.16 MWdc STC
ANNUAL AC PRODUCTION: 1,802 MWh

Equipment Specifications

MODULES: 4,844 Sharp NU-Q24OF2, 240 W STC, +10/-5%, 7.98 Imp, 30.1 Vmp, 8.65 Isc, 37.4 Voc
INVERTERS: 3-phase, 277/480 Vac service; two Advanced Energy Solaron 500 kW PV, 500 kW, ±600 Vdc maximum input, ±330–±600 Vdc operating range
ARRAY: 14 modules per source circuit (3,360 W, 7.98 Imp, 421.4 Vmp, 8.65 Isc, 523.6 Voc), inverter 1: 172 source circuits (577.9 kW, 1,372.6 Imp, 421.4 Vmp, 1,487.8 Isc, 523.6 Voc), inverter 2: 174 source circuits (584.6 kW, 1,388.5 Imp, 421.4 Vmp, 1,505.1 Isc, 523.6 Voc); 1.16 MW array capacity total
ARRAY INSTALLATION: Two custom canopy structures, Unirac ISYS Roof Mount racking, 235° azimuth, 5° tilt
ARRAY STRING COMBINERS: 32 SolarBOS Disconnect Combiners, 15 A fuses
SYSTEM MONITORING: Deck Monitoring production and environmental monitoring

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One of the preliminary design goals for the BRC Group of Companies’ installation was a target array capacity of 300 kWdc mounted on a commercial facility with less than 35,000 square feet of roof area. The building had been constructed in phases, resulting in three different roof heights and numerous existing roof penetrations, and was very long and narrow, with an azimuth of 135°. After many design revisions, an innovative elevated array racking structure was developed to maximize array power density on the physically constrained rooftop.

The design team proposed the elevated array to equalize the roof heights and allow sufficient access for future roof maintenance. At the owners’ request, three roofing companies were consulted to determine the minimum height for the array’s racking structure. A height of 5 feet above the highest roof section was deemed acceptable, which resulted in an average roof-to-rack clearance of 9 feet over the entire surface. Having determined the proper clearances, the facility owner contracted Rob Thorne of Canadian Renovations & Restorations to engineer the racking system.

The building azimuth constrained the racking system in two ways: It increased the difficulty of designing the superstructure for the maximum wind and snow-load conditions in the area, and the module racking trusses needed to be independent of the superstructure to allow for azimuth-based adjustments relative to the building. To accommodate the target array capacity, the design team determined that the array would need to be cantilevered over the building envelope on three sides. The modules were configured two-up in landscape format at 19º tilt with sufficient spacing intervals to eliminate the possibility of interrow shading based on the site latitude.

Due to the age of the building and the lack of detailed structural drawings, the design and engineering teams excavated footings in three locations within the building to assess soil type. This allowed them to determine the footing details required to support the weight and wind load of the elevated array structure. Additional engineering called for 23 new roof support columns and 41 wall column extensions consisting of 24-inch steel stubs that would serve as mounting points for the array superstructure.

The hot-dipped, zinc-coated I-beam superstructure was fabricated and installed, with triangular truss module racking secured to the superstructure. The completed design accommodated 1,623 Juli New Energy modules that met the 300 kW array capacity goal, and 21 Power-One string inverters were selected based on their high efficiency and dual MPPT inputs. The inverters were mounted to the superstructure in an easy-to-service, readily accessible manner.

“We constructed the raised-roof solar array out of necessity. However, the design and installation experience, and subsequent performance and financial analysis, indicated that ‘building up’ yields a higher-performing system compared to arrays mounted on the roof deck. Additionally, elevated arrays provide full access for roof maintenance. We commissioned a second 250 kW elevated array in 2011 and have three more planned for 2012.”

Rob Thorne, Canadian Renovations & Restorations

Overview

DEVELOPMENT GROUP: Solarform, cdnsolarform.com
DESIGNERS: Bill Melnik, president, BRC Group of Companies, brccanada.com; Rob Thorne, president, Canadian Renovations & Restorations, sites.google.com/site/ renovationsandrestorations
LEAD INSTALLER: Rob Thorne, Canadian Renovations & Restorations
DATE COMMISSIONED: July 21, 2011
INSTALLATION TIME FRAME: 60 days
LOCATION: Georgetown, Ontario, Canada, 43.7°N
SOLAR RESOURCE: 4.0 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: Per Environment Canada (climate.weatheroffice.gc.ca) 99°F/-13°F
ARRAY CAPACITY: 308.4 kW
ANNUAL AC PRODUCTION: 365 MWh

Equipment Specifications

MODULES: 1,623 Juli New Energy JLS72M190W, 190 W STC, +3/-0, 5.12 Imp, 36.5 Vmp, 5.83 Isc, 43.8 Voc
INVERTERS: 3-phase, 600 Vac service (grid interconnection via 480/600 Vac step-up transformer); 19 Power-One Aurora Trio PVI-12.0-I-OUTD-US-480, 12.0 kW, 520 Vdc maximum input voltage, 250–470 Vdc MPPT range (two MPPT channels per inverter); two Power-One Aurora Trio PVI-10.0-I-OUTD-US-480, 10.0 kW, 520 Vdc maximum input voltage, 220–470 Vdc MPPT range (two MPPT channels per inverter)
ARRAY: 12 kW inverters: 10 modules per source circuit (1,900 W, 5.12 Imp, 365 Vmp, 5.83 Isc, 438 Voc); four source circuits per MPPT channel (7,600 W, 20.48 Imp, 365 Vmp, 23.32 Isc, 438 Voc); eight source circuits per inverter (15.2 kW total, 288.8 kW subarray total); 10 kW inverters: 19.6 kW subarray total
ARRAY INSTALLATION: Custom raised-roof mount elevated 9 feet (average) above building roof, galvanized steel I-beam superstructure, angled truss module racking above superstructure, 180° azimuth, 19° tilt
ARRAY STRING COMBINERS: Inverter integrated, 15 A fuses
SYSTEM MONITORING: Two Power- One dataloggers connected to Ethernet via RS-485, Davis Instruments weather station with Weather-Link software (Fat Spaniel software integrates performance and environmental monitoring)

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The PV system installed at the Mineta San Jose International Airport Rental Car Center is the largest municipal PV project in San Jose, California, to date and is one of the largest solar arrays located at an airport in the US. The array covers 3.4 acres and is larger than two football fields. The system was part of a $1.3 billion initiative by the City of San Jose to modernize the airport. It was chosen as the grand prize winner of the “Win with Canadian Solar” contest based on engineering skill, environmental impact, creativity and aesthetics. The system will meet at least 20% of the facility’s electrical power needs, reduce operational costs and generate a net-positive return on investment.

This project involved significant design, installation and scheduling challenges. The Rental Car Center is a seven-level building that operates 24 hours a day, and the installation needed to be completed in 2 months. Because the project was located adjacent to an airport, the crews had to account for high winds, heavy traffic and other significant, ongoing airport improvement projects.

The Mineta San Jose International Airport is located in Seismic Zone 4, meaning that it sits on a location that is at the greatest risk in the nation of being hit by an earthquake. The designers had to be very cognizant of the amount of weight placed on the roof structure. Therefore, a ballasted racking approach was eliminated in favor of Unirac’s ISYS Roof Mount. The nonballasted solution, which had never been deployed on such a large scale, requires fewer roof penetrations than other racking systems that were considered.

The Rental Car Center has an elastomeric roof covering a structural concrete deck. Each array standoff is secured with four expansion bolts. A combination of sealant and individual curbs for each standoff provides superior weatherproofing. The ISYS Roof Mount installation instructions detail laying out a series of modules on the roof deck, fastening the rails and then flipping the array assembly into place atop the racking substructure. During this particular installation, after many attempts, it was determined that it was simpler to install the rails first and then slide the individual modules into place for fastening.

“Numerous obstacles challenged the construction team to come up with unique solutions for problems such as material hoisting, material and debris handling, and scheduling activities with the airport officials. Despite these challenges, the installation was finished safely and in record time.”

—Don Dixon, Rosendin Electric

Overview

DESIGNER: Jason Zvanut, chief operating officer, iPower, ipowercorp.com
LEAD INSTALLER: Don Dixon, senior project manager, Rosendin Electric, rosendin.com
DATE COMMISSIONED: May 201
INSTALLATION TIME FRAME: 60 days
LOCATION: San Jose, CA, 37.4°N
SOLAR RESOURCE: 5.3 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per solarabcs.org/permitting/map: 89.6°F/32°F
ARRAY CAPACITY: 1.12 MW
ANNUAL AC PRODUCTION: 1,700 MWh

Equipment Specifications

MODULES: 4,680 Canadian Solar CS5P-240M, 240 W STC, +/-2.1%, 4.99 Imp, 48.1 Vmp, 5.34 Isc, 59.4 Voc
INVERTERS: 3-phase, 480 Vac service, two Advanced Energy Solaron 500E, 500 kW, 600 Vdc maximum input, bipolar ±330 to ±600 Vdc MPPT range
ARRAY: Nine modules per source circuit (2,160 W, 4.99 Imp, ±432.9 Vmp, 5.34 Isc, ±534.6 Voc), 32 circuits per combiner typical (69.1 kW, 159.7 Imp, ±432.9 Vmp, 170.9 Isc, ±534.6 Voc), 260 source circuits per inverter, 130 positive and 130 negative-to-ground (561.6 kW, 648.7 Imp, ±432.9 Vmp, 694.2 Isc, ±534.6 Voc)
ARRAY INSTALLATION: Unirac ISYS Roof Mount system installed on concrete slab roof structure weatherproofed with elastomeric roofing material, 280° azimuth, 10° tilt
ARRAY COMBINERS: Sixteen Cooper Crouse-Hinds CCBS34 (eight per inverter), 10 A fuses
SYSTEM MONITORING: SolarMagic MYPVDATA

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John and Laryna Rodriguez wanted to invest in a PV system that would offset a substantial portion of their energy needs. However, their home’s south-facing roof had room for only eight modules. To overcome this challenge, Photon Solar Power specified a SolarEdge inverter and power optimizer system that allows for multiple array orientations with a single inverter. The original plan was to install 16 additional modules on the home’s east-facing roof. After consulting with SolarEdge and Aleo Solar, the team decided to install the 16-module array on the west-facing roof to maximize energy production, mainly due to San Diego’s microclimate.

The combination of Quick Mount PV Flat Tile mounts and Unirac SolarMount racking made the rooftop installation flow smoothly. Initially, it took some time to determine the best method to mount the dc optimizers to the racking system and properly manage the conductors between the optimizers. Using a transformerless product also required an adjustment to our standard wiring and installation process. The monitoring system, which utilizes dc conductors for communication, is straightforward and easy to install and configure. The clients appreciate the module-level monitoring, and the SolarEdge products’ integrated safety features are a strong selling point.

“The Rodriguez residence was featured on the 2011 San Diego Solar Homes Tour and drew a lot of attention due to the dualorientation array installation. After working out the initial kinks of using SolarEdge electronics on the rooftop, the added flexibility, increased energy harvest and monitoring tools have made the solution my default offering to clients.”

—Pekka Laine, Photon Solar Power

Overview

DESIGNER AND LEAD INSTALLER: Pekka Laine, president, Photon Solar Power, photonsolarpower.com
DATE COMMISSIONED: June 2011
INSTALLATION TIME FRAME: 5 days LOCATION: San Diego, CA, 33°N
SOLAR RESOURCE: 5.72 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per solarabcs.org/permitting/map: 79°F/41°F
ARRAY CAPACITY: 5.52 kW
ANNUAL AC PRODUCTION: 9,200 kWh

Equipment Specifications

MODULES: 24 Aleo Solar S18.230, 230 W STC, +4.99/-0 W, 7.90 Imp, 29.1 Vmp, 8.44 Isc, 36.6 Voc
INVERTER: SolarEdge SE6000US, 6 kW, 500 Vdc maximum input, 350 Vdc nominal input voltage (fixed and controlled by inverter), 240 Vac output; 24 SolarEdge Power Optimizers, PB250-AOB, 250 W, 60 Vdc maximum input, 5–60 Vdc MPPT range
ARRAY: 12 modules per source circuit (2,760 W, 7.9 Imp, 349.2 Vmp, 8.44 Isc, 439.2 Voc), two circuits total (5,520 W, 15.8 Imp, 349.2 Vmp, 16.9 Isc, 439.2 Voc)
ARRAY INSTALLATION: Flush-toroof array, Quick Mount PV Flat Tile mounts, Unirac SolarMount racking; eight modules at 190° azimuth, 18° tilt; 16 modules at 280° azimuth, 18° tilt
SYSTEM MONITORING: SolarEdge Monitoring Portal and Apple iPhone app

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Velocitel Energy Solutions contracted directly with BP Solar to install a 561 kW PV array at the Pico Rivera Towne Center, a large retail mall in southeastern Los Angeles, California. The design team had to consider extensive existing rooftop conditions, including 198 skylights, and the relocation of hundreds of feet of HVAC gas and condensation pipes, as well as 350 new roof penetrations and attachment points.

The rooftop skylights presented two challenges: providing fall protection for workers and accommodating an irregular array layout. Prior to mobilization, fall protection railings were erected around every skylight. Twenty-eight separate subarrays comprised the array layout, and installation crews needed to double and triple check the subarray locations before beginning to install each one. The roof was split into three zones, with a separate installation team dedicated to each zone. Teams worked from south to north, panelizing the modules for mounting to the SunLink supports at workstations that migrated south to north along with the installation progress.

Due to seismic considerations, the designers were required to locate 10 to 15 attachment points to the building per subarray. These followed an irregular pattern due to the segmented array layout. A team of roofers preceded each array installation crew. The roofers cut holes in the roof membrane and insulation down to the corrugated metal roof deck at points identified by a surveyor. The roofers then attached cylindrical stanchions to the roof deck and flashed the penetrations with TPO single-ply roofing membrane that followed the membrane manufacturer’s published specification.

The electrical side of the installation faced its own set of challenges. The utility transformer that fed the store switchgear was an older unit that needed to be replaced. However, the utility was not aware that shutting down the transformer during the PV system interconnection was too dangerous in the transformer’s current state. Just hours before the scheduled outage, after weeks of preparation and the scheduling of a 1 MW backup generator and refrigeration trucks—as well as teams from BP Solar, Blue Oak Energy, Southern California Edison, Velocitel, SASCO and the building owner—the utility canceled the shutdown due to the unsafe conditions inside the transformer. The interconnection had to be rescheduled for after the transformer was replaced. Several weeks later, the interconnection was successfully completed during a 2am outage that had no negative impacts on the stores’ operations.

Ultimately, despite the challenges, the installation was completed within budget and on schedule to the satisfaction of BP Solar and the building owner.

“The complex nature of this installation required the expertise of many different trades. Electricians, plumbers, roofers, surveyors, civil contractors, fencing contractors, safety consultants, utility workers and retail managers all worked together to deliver the project. It was a true team effort.”

Morgan Vickery, Velocitel Energy Solutions

Overview

DESIGNER: Jayme Garcia, PE, electrical engineer, Blue Oak Energy, blueoakenergy.com
PROJECT MANAGER: Morgan Vickery, Velocitel Energy Solutions, energy.velocitel.com
DATE COMMISSIONED: August 2010
INSTALLATION TIME FRAME: 68 days
LOCATION: Pico Rivera, CA, 34.1°N
SOLAR RESOURCE: 5.66 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per solarabcs.org/permitting/map: 88°F/36°F
ARRAY CAPACITY: 561 kW
ANNUAL AC PRODUCTION: 905.5 MWh

Equipment Specifications

MODULES: 3,300 BP Solar 3170N, 170 W STC, -3%/+5%, 4.8 Imp, 35.6 Vmp, 5.2 Isc, 44.3 Voc
INVERTERS: 3-phase, 277/480 Vac service, two Schneider Electric Xantrex GT250-480, 250 kW, 600 Vdc maximum input, 300–480 Vdc MPPT range
ARRAY: 12 modules per source circuit (2,040 W, 4.8 Imp, 427.2 Vmp, 5.2 Isc, 531.6 Voc); 139 source circuits on Inverter One (284 kW, 667.2 Imp, 427.2 Vmp, 722.8 Isc, 531.6 Voc); 136 source circuits on Inverter Two (277 kW, 652.8 Imp, 427.2 Vmp, 707.2 Isc, 531.6 Voc)
ARRAY INSTALLATION: SunLink Roof Mounting System installed on single-ply thermoplastic olyphen (TPO) membrane, 213° azimuth, 20° tilt
ARRAY STRING COMBINERS: 24 Steven Engineering String Combiner, 9 A fuses
SYSTEM MONITORING: National Semiconductor/Energy Recommerce RECtrack 3

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A collaborative effort between the Colorado Rocky Mountain School (CRMS), the Aspen Skiing Company and Xcel Energy, the CRMS Solar Farm broke ground only after lengthy negotiations. The numerous approvals involved made the design challenges seem simple by comparison.

The main electrical design challenge was proper wire and conduit sizing on the ac side of the system. CRMS, like many schools, has a 3-phase 208 service. In order to run a relatively low ac volt- age over a long distance with minimal voltage drop, 3/0 copper was used from each Sunny Tower to the utility interconnection. This increased costs and posed minor logistical hassles. Meridian Energy Systems in Austin, Texas, provided consultation services to the Sunsense design team.

Infrastructure requirements for the project were considerable. These included trenching and burying conduit, as well as laying down service roads. A fencing contractor provided both the perimeter fence and the array’s struc- tural foundation. Only after the infra- structure was complete could the instal- lation team begin its work.

The Sunny Towers provided for more than a clean and convenient installation; they also make detailed performance monitoring easy. Referring to the online SMA Sunny Portal allows the owners, operators or maintenance personnel to verify performance for each inverter and subarray.

"Thanks to our crafty installation team, the project went even smoother than expected. Columns of modules were assembled on the ground. Using a custom harness and an extension reach forklift, each six-module panel was lifted into place. This innovation dramatically improved installation efficiency."

--Scott Ely, Sunsense

Overview

DESIGNER: Scott Ely, President, Sunsense, sunsensesolar.com
LEAD INSTALLER: Jeff Lauckhart, Operations Manager, Sunsense
DATE COMMISSIONED: July 2008
INSTALLATION TIMEFRAME: 90 days
LOCATION: Carbondale, CO, 39.6º N
AVERAGE SOLAR RESOURCE: 5.36 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: -39º F / 89º F
ARRAY CAPACITY: 147.42 kW STC
AVERAGE ANNUAL AC PRODUCTION: 208 MWh

Equipment Specifications

MODULES: 756 BP Solar SX3195S, 195 W STC, +9%/-9%, 7.96 Imp, 24.4 Vmp, 8.6 Isc, 30.7 Voc
INVERTERS: 3-phase, 208 Vac system, 3 SMA Sunny Towers, 42 kW each, 6 SB7000US per tower, 600 Vdc maximum input, 250–480 Vdc MPPT range.
ARRAY: Eighteen 42 module subarrays—14 modules per string (2,730 W, 7.96 Imp, 341.6 Vmp, 8.6 Isc, 429.8 Voc), 3 strings per inverter (8,190 W, 23.9 Imp, 341.6 Vmp, 25.8 Isc, 429.8 Voc)
ARRAY INSTALLATION: Nine Direct Power & Water Large Ground Mount, 84 modules each, 180º azimuth, 35º tilt
ARRAY COMBINER: 15 A fuses in Sunny Towers
SYSTEM MONITORING: Revenue grade meter from Xcel Energy; SMA Sunny WebBox with sensor package monitored via Sunny Portal

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The Greg and Malia Kupillas residence is located at the end of a utility transmission line in Oregon’s rural Clackamas County. The homeowners seasonally experience power outages that can last for several days. When the Growing Solar Clackamas County bulkbuy community project was announced in 2012, they saw the opportunity to invest in a PV system that would not only offset a percentage of their annual energy use, but also provide the backup energy security they were looking for.

Sunlight Solar Energy worked closely with the homeowners to develop a 7.2 kW system that provides 3 days of autonomy for critical loads, which include home business equipment, lighting and limited water pumping. Sunlight Solar helped the owners develop a plan for load shedding based on battery state of charge in the event of extended power outages during inclement weather.

The array is installed on a shop building that was originally designed with a PV array installation in mind. However, the Oregon Solar Installation Specialty Code that was enacted after construction required rafter sistering. To increase solar exposure on the array, trees near the south- and southwestfacing portions of the shop were harvested prior to the installation.

“The Kupillas system was challenging due to the inherent complexity of nonprescriptive design. Projecting the system’s power and energy requirements during utility outages involved a lot of input from the homeowners, which was an essential component of developing a backup system that met their expectations.”

Dustin Wilson, Sunlight Solar Energy

Overview

DESIGNER: Marc Chambers, supervising electrician, Sunlight Solar Energy, sunlightsolar.com
LEAD INSTALLER: Dustin Wilson, journeyman electrician, Sunlight Solar
DATE COMMISSIONED: Sept. 2012
INSTALLATION TIME FRAME: 4 days
LOCATION: Mulino, OR, 45.2°N
SOLAR RESOURCE: 3.9 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: 90°F/23°F
ARRAY CAPACITY: 7.2 kWdc STC
ANNUAL AC PRODUCTION: 7,039 kWh

Equipment Specifications

MODULES: 30 SolarWorld Sunmodule SW 240 poly, 240 W STC, +5/-0 W, 7.96 Imp, 30.2 Vmp, 8.44 Isc, 37.2 Voc
INVERTER: Single-phase, 120/240 Vac service; one OutBack Power Radian GS8048, 8 kW, 48 Vdc nominal input, 120/240 Vac output
CHARGE CONTROLLERS: Two Outback Power FLEXmax 80, 80 Adc at 40°C, 150 Vdc maximum input, configured for 48 Vdc nominal output
BATTERIES: Four Concord Sun Xtender PVX-2580L, AGM, 12 Vdc nominal, 258 Ah at 24-hour rate, 258 Ah bank capacity at 48 Vdc nominal
ARRAY: Three modules per source circuit (720 W, 7.96 Imp, 90.6 Vmp, 8.44 Isc, 111.6 Voc), five source circuits per charge controller (3,600 W, 39.8 Imp, 90.6 Vmp, 42.2 Isc, 111.6 Voc); 10 source circuits total (7,200 W, 70.6 Imp, 90.6 Vmp, 84.4 Isc, 111.6 Voc)
ARRAY INSTALLATION: Ribbed metal roofing, S-5! VersaBracket mounts, Unirac SolarMount racking, 180° azimuth, 18° tilt
ARRAY COMBINERS: Two MidNite Solar MNPV12-150, 15 A CBs
SYSTEM MONITORING: Outback MATE3 display and controller, Outback HUB4 Communications Manager

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The PV installation at Otto Peterson Elementary School in Scappoose, Oregon—a new construction project— required close collaboration with the general contractor, P&C Construction, and the architect, DLR Group. Product delivery and installation timing were critical, while in-field design changes and construction flexibility were important for the installation team.

To minimize the amount of racking materials used and maximize energy production, a low-profile tilt racking system was specified for the standing-seam metal roof. A proprietary seam clamp system was used to eliminate roof penetrations while allowing a tilt angle for the modules. This approach limits wind loading and allows for a more power-dense rooftop installation. The tilted rows also allow for better access to the modules for array maintenance.

Maximizing the production of the awning arrays posed some architectural challenges. For example, REC Solar’s performance standards required a lower row of proposed awnings to be eliminated due to excessive shading from the building. In addition, the awning arrays needed several adjustments to ensure that they were appropriate for the string and inverter sizing and that they fit the window openings, both aesthetically and structurally. Due to the long distances between each of the three awning sections, splitting strings was not a viable option.

“Solar systems on schools are always dual-value projects: they provide a tangible example of solar with on-site educational opportunities for students, while helping the schools reduce their overall operating expenses.”

— Andy Noel, regional manager, REC Solar

Overview

DESIGNER: Adam Ward, design engineer, REC Solar, recsolar.com
PROJECT MANAGER: Bryan Shull, operations manager, REC Solar
DATE COMMISSIONED: Sept. 2010
INSTALLATION TIME FRAME: 20 days
LOCATION: Scappoose, OR, 45.8°N
SOLAR RESOURCE: 4 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per solarabcs.org/permitting/map: 89.6°F/19.4°F
ARRAY CAPACITY: 33 kW
ANNUAL AC PRODUCTION: 33 MWh

Equipment Specifications

MODULES, ROOF: 134 REC220AEUS, 220 W STC, +/-3%, 7.8 Imp, 28.4 Vmp, 8.4 Isc, 36.4 Voc
MODULES, AWNINGS: 18 Sanyo HIP- 195DA3, 195 W STC, +10%/-0%, 3.5 Imp, 55.8 Vmp, 3.73 Isc, 68.7 Voc
INVERTERS: 3-phase, 277/480 Vac service, three SB 7000-US, 7kW, 600 Vdc max. input, 250–480 Vdc MPPT range; two SMA SB 5000-US, 5 kW
ARRAY, ROOF: Twelve REC 220 W modules per source circuit on three SB 7000-US inverters (2,640 W, 7.8 Imp, 340.8 Vmp, 8.4 Isc, 436.8 Voc), three circuits per inverter (7,920 W, 23.4 Imp, 340.8 Vmp, 25.2 Isc, 436.8 Voc); 13 modules per source circuit on one SB 5000-US inverter, two circuits total
ARRAY, AWNINGS: Six Sanyo 195 W modules per source circuit (1,170 W, 3.5 Imp, 334.8 Vmp, 3.73 Isc, 412.2 Voc, three circuits on SB 5000-US inverter (3,510 W, 10.5 Imp, 334.8 Vmp, 11.2 Isc, 412.2 Voc)
ARRAY INSTALLATION, ROOF: Proprietary seam clamp and SnapNrack tilt mount kit, 156° azimuth, 16° tilt
ARRAY INSTALLATION, AWNINGS: Custom fabricated curtain wall brackets and racking, 180° azimuth, 15° tilt
SYSTEM MONITORING: SMA Webbox

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The Senate Gymnasium at Ulster County Community College (SUNY Ulster) in Stone Ridge, New York, has incorporated solar water heating into its buildings’ efficiency plan to employ the most cost effective strategy for reducing energy costs on the campus. The project was included in an energy efficiency performance contract by Johnson Controls. A drainback configuration was used, because the high limit controls the system without any overheating concerns when school is not in session.

Careful planning helped to avoid complications or scheduling issues that can arise when coordinating with other building trades in a very limited space. Fortunately, the relatively small mechanical room had a high ceiling, and it was put to use. Up was the only way to go to install the drainback tanks.

Another hurdle was the flat roof. The collectors were oriented 35° East of South due to the truss construction. The reduced heating capacity of the slightly less than optimal orientation was partially offset by the reflected radiation from the white roof surface.

"This project is a testament to the training and knowledge shared by solar pros like Bill Guiney, Rich Bonte and Tom Lane. These guys, with a combined experience of almost 100 years, have encouraged, instructed and mentored people like me as we try to build awareness in communities and governments that solar thermal will fit on an awful lot of roofs. It has unlimited application for power generation and energy independence, one shower at a time."

Patrick Gallagher, Gallagher Solar Thermal

Overview

DESIGNER: Patrick Gallagher, owner, Gallagher Solar Thermal, solarthermalsolution.com
LEAD INSTALLERS: Patrick Gallagher and Derek Quigley, Gallagher Solar Thermal
DATE COMMISSIONED: August 2008
INSTALLATION TIMEFRAME: 40 hours
LOCATION: Stone Ridge, NY, 41.85° N
SOLAR RESOURCE: 3.78 KWh/m2/day
ANNUAL HEATING DEGREE DAYS: 5,851
RECORD LOW TEMPERATURE: -19ºF
COLLECTOR AREA: 200 square feet
AVERAGE ANNUAL PRODUCTION: 12 MWh

Equipment Specifications

COLLECTORS: Five SunEarth EC-40 collectors, 40 square feet each, black chrome absorber
STORAGE: Two existing 120 gallon A.O. Smith tanks preheat a 200 gallon gas fired water heater
HEAT EXCHANGER: Two AET 20 Gallon DBX Drainback Tanks, each with 20 square foot internal heat exchangers
PUMPS: Drainback/Glycol loop Grundfos UP 26-96, DHW Grundfos UP15-42SS
CONTROL: Steca SunEarth 0301U differential temperature control
FREEZE CONTROL: Drainback, propylene glycol
COLLECTOR INSTALLATION: Sloped roof curbs on flat roof, collectors sloped 0.25 inch per foot, 145º azimuth, 45° tilt

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Southern California Edison (SCE) is one of the nation’s largest electric utilities serving nearly 14 million people in central, coastal and southern California. In 2008, SCE launched a 250 MW solar initiative. To help achieve some of SCE’s solar goals, Cupertino Electric Inc. (CEI) constructed a 6.77 MW solar farm in Porterville, California.

Given the size and scope of the project, it would normally have taken 5–6 months to complete. Yet it was completed in an unprecedented 50 days to allow SCE to meet its renewable portfolio standard goals associated with its 250 MW initiative. Despite the project’s fasttrack status—requiring around-the-clock labor—there were no injuries on the job site that required days away.

The site was already zoned for industrial use, which eliminated any land-use issues and significantly helped to complete the project in a short time frame. The ground conditions at the site presented some unique challenges when it came to implementing the piledriven pole design for the Schletter preengineered and prefabricated racking system, however. The hard soil was difficult to penetrate. CEI had to increase the manpower and number of pile-driving machines at the project to get the poles driven without pushing back the completion date.

Under SCE’s direction, Lewis Ross Associates determined the array’s electrical design. In the array field, SCE utilized Shoals combiner boxes with 15 strings per combiner. To accommodate the number of strings and combiner boxes at the array, CEI installed two Shoals-fused recombiner cabinets at each inverter. The cabinets each have eight 200 A fused disconnects, allowing the PV output circuits to transition into two PV input circuits.

The project consists of 10 inverters with output voltages of 208 Vac each, which are fed directly into step-up transformers that boost the voltage to 12 kV for utility interconnection. Each inverter and step-up transformer is installed on a 14-by-25-foot pad near the array. The installation has two circuits for interconnection to help reduce conductor costs on the high-voltage side. Each circuit consists of five transformers wired in an open-loop configuration. The open loop allows the transformers to share service conductors, eliminating the need for homerun feeders from the main switchgear to individual transformers. This has the upside of reducing conductor and associated disconnect requirements. Due to the open-loop wiring design, all downstream transformers and inverters must be disconnected when one inverter is disconnected for maintenance.

“This large-scale project required an immense amount of coordination, attention to detail and focus on safety. Our successful history of first-of-their-kind, fast-track projects enabled us to approach this project with innovative solutions to maximize efficiency and safety in engineering, procurement and construction.”

Meisa Kassis, CEI

Overview

DESIGNER: Gene Vanderford, PE, principal, Lewis Ross Associates, lewisrossassociates.com
PROJECT MANAGER: Meisa Kassis, LEED AP, construction project manager, Cupertino Electric Inc., cei.com
DATE COMMISSIONED: December 2010
INSTALLATION TIME FRAME: 50 days
LOCATION: Porterville, CA, 36°N
AVERAGE SOLAR RESOURCE: 5.65 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per solarabcs.org/permitting/map: 100°F / 28°F
ARRAY CAPACITY: 6.77 MW
AVERAGE ANNUAL AC PRODUCTION: 9,730 MWh

Equipment Specifications

MODULES: 29,428 Trina TSM- 230PA05, 230 W STC, +3%/-3%, 7.66 Imp, 30.0 Vmp, 8.18 Isc, 37.0 Voc
INVERTERS: 3-phase, 208 Vac service, 10 Satcon PowerGate Plus 500, 500 kW, 600 Vdc maximum input, 333–600 Vdc max MPPT range
ARRAY: 14 modules per source circuit (3,220 W, 7.66 Imp, 420 Vmp, 8.18 Isc, 518 Voc), 15 source circuits per combiner box (48.3 kW, 114.9 Imp, 420 Vmp, 122.7 Isc, 518 Voc); 210 source circuits per inverter typical (676.2 kW, 1,608.6 Imp, 420 Vmp, 1,717.8 Isc, 518 Voc)
ARRAY COMBINERS: 147 Shoals combiner boxes, 15 A fuses; 2 Shoals recombiners per inverter (20 total), each with 8 fused 200 A disconnects
ARRAY INSTALLATION: Schletter fixed tilt, ground-mount racking system, 180° azimuth, 25° tilt
SYSTEM MONITORING: Southern California Edison custom monitoring

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