Project Profiles

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In May 2011, VF Outdoor, a subsidiary of VF Corporation, broke ground on its four-building, 11-acre, 160,000-square-foot campus in Alameda, California, to consolidate locations for three VF brands: The North Face, lucy and JanSport.

Consistent with these brands’ commitment to the environment and innovative design, the campus incorporates many sustainability features, including indirect evaporative cooling HVAC that requires no compressors or refrigerants, energy-efficient T-5 lighting with motion sensors, FSC-certified wood, low-flow water fixtures, denim insulation, EV charging stations, vertical wind turbines and solar shades over the building windows on the east, south and west sides.

Even after construction was under way, VF’s internal sustainability team continued exploring how to achieve its goal of net zero energy. VF tasked Sunlight Electric with achieving net zero status with PV while addressing and overcoming several issues and challenges. Limited roof space with 12-foot-high mechanical screens on the four building roofs reduced unshaded space for PV arrays. Unshaded space was also limited in the parking lot, and there was no space for ground-mount arrays, nor did the client wish to lose any parking spaces.

To overcome these site obstacles, Sunlight Electric designed a distributed PV system that includes four roofmounted arrays and 12 carport arrays. A basic design emerged using Hyundai Heavy Industries’ HiS-M230SG modules on all roofs and carport locations. Hyundai agreed to eliminate any marine warranty exclusions without the added measures some other manufacturers require. With sites and modules selected, Sunlight Electric then looked at all the other project elements that it could incorporate to meet VF’s needs. REFUsol’s unique inverter capacity range (12, 16, 20 and 23.2 kW), 480 Vac/3-phase output, compact size and light weight enabled a cost-effective solution that complemented the system’s distributed design approach.

This VF project was the first US application for Schletter’s Park@Sol carports, which offer the durability of anodized aluminum and a major aesthetic advantage over traditional galvanized steel, cantilevered-box post-and-beam structures. Genmounts’ custom-bent aluminum ballast pans enabled fine-tuning of the roof array tilt angles to the exact design requirements. All of these elements helped achieve the goal of respecting the design aesthetic of VF Outdoor’s modern campus.

“We were not satisfied with only a small percentage of our energy coming from renewable resources and believe our workplace should reflect our commitment to environmental responsibility. As a business, we define sustainability as achieving environmental, social and fiscal responsibility. This photovoltaic project with Sunlight Electric is a great example of meeting these requirements.”

Adam Mott, senior manager of sustainability, The North Face

“This project is the quintessential illustration of Sunlight Electric’s needs-driven design ethos. As The North Face might say—never stop exploring—for the right technical and engineering solutions.”

Rob Erlichman, CEO and founder, Sunlight Electric

Overview

DESIGN FIRM: Sunlight Electric, sunlightelectric.com
INSTALLATION FIRM: Shamrock Renewable Energy Services, shamrockrenewable.com
DATE COMMISSIONED: December 2012
INSTALLATION TIME FRAME: 160 days
LOCATION: Alameda, CA, 37.8°N
SOLAR RESOURCE: 5.3 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per Solar ABCs solar reference map: 77°F/34°F
ARRAY CAPACITY: 855 kWdc STC
ANNUAL AC PRODUCTION: 1,123 MWh

Equipment Specifications

MODULES: 3,720 Hyundai HiSM230SG, 230 W STC, +3/-0%, 7.9 Imp, 29.4 Vmp, 8.4. Isc, 36.9 Voc
INVERTERS: 3-phase, 277/480 Vac service; 39 inverters total; 19 REFUsol 024K-UL, 23.2 kW; six REFUsol 020KUL, 20 kW; six REFUsol 016K-UL, 16 kW; eight REFUsol 012K-UL, 12 kW; 500 Vdc maximum input, 125–450 Vdc MPPT range, 480 Vac/3-phase wye output
ARRAY SCHEDULE, ROOF MOUNTED: Building A (20.2 kW), B (69 kW), C (69 kW), D (98 kW); 256 kW array capacity total
ARRAY SCHEDULE, CARPORTS: Carport 1 (37.3 kW), 2 (35.9 kW), 3 (23.5 kW), 4 (147.2 kW), 5 (30.4 kW), 6 (31.7 kW), 7 (24.8 kW), 8 (15.2 kW), 9 (119.6 kW), 10 (23.5 kW), 11 (82.8 kW), 12 (27.6 kW); 599 kW array capacity total
ARRAY INSTALLATION, ROOF MOUNTED: TPO roofing, Genmounts ballasted racking system, 218° azimuth, 5° tilt
ARRAY INSTALLATION, CARPORTS: Schletter Park@Sol racking canopies, 128°–218° azimuths, 5° tilt
SYSTEM MONITORING: DECK Monitoring with custom user interface integrating existing solar window shade project and wind turbine installations

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Habitat for Heroes is a 27-unit housing development for low income families and veterans being built by Habitat for Humanity of Orange County, California. Each of the homes has a 1.4 kW grid-tied PV system aimed at reducing the home- owner’s electricity bills by up to 70%. A public/private partnership—consisting of Akeena Solar, Morgan Stanley Solar Solutions and the Community Action Partnership of Orange County (CAPOC) funded through the state of California—was formed to provide the PV systems.

Workers with no previous solar experience are involved in the project, including CAPOC weatherization field crews, the Orange County Conservation Youth Corps and Habitat for Humanity volunteers, so ease of installation and simplicity of design are a must. Akeena Solar’s Andalay AC panel system is an ideal solution.

Each Andalay AC solar panel has an integrated Enphase microinverter. The ac output of groups of eight panels forms a dedicated branch circuit. A flashed, roof mount SolaDeck junction box—a part in RSTC Enterprises’ Comm-deck product line (rstcenterprises.com)—is used to transition conductors off the roof. The ac wiring is run through interior walls, like any other branch circuit, and interconnects via a 15 A circuit breaker.

Time on the roof is minimized due to Andalay’s frame-integrated mounting system. No additional racking is required. Flashed standoffs ensure that the tile roof remains watertight.

“We created four working groups using 25 crew members from three different companies—all of whom were new to solar—and installed four systems in one day. Participants were able to build off their trade experience and quickly learned how to install these panels.”

Tom Spangler, CAPOC field superintendent

Overview

DESIGNERS: Patra Ngaotheppitak, solar design engineer, and David Baker, mechanical engineering manager for research and development, Akeena Solar, akeena.com
LEAD INSTALLER: Tom Spangler, field superintendent, Community Action Partnership of Orange County, capoc.org
DATE COMMISSIONED: August 2009
INSTALLATION TIMEFRAME: Four homes per day
LOCATION: San Juan Capistrano, CA, 33.5°N
SOLAR RESOURCE: 5.7 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: 21°F / 79°F
ARRAY CAPACITY: 1.4 kW
AVERAGE ANNUAL AC PRODUCTION: 2,075 kW

Equipment Specifications

MODULES: Eight Andalay ST175-1, 175 W STC, +3%/−3%, 4.95 Imp, 35.2 Vmp, 5.2 Isc, 44.2 Voc
INVERTERS: Eight Enphase M190-72-240-S12, 190 W, 54 Vdc maximum input, 22–40 Vdc MPPT range, single-phase, 240 Vac output
ARRAY: Eight inverters per branch circuit
ARRAY INSTALLATION: Roof mount on flat tile roof, Andalay flat tile mounts, 213° azimuth, 22° tilt
SYSTEM MONITORING: Enphase Enlighten online monitoring, revenue-grade kWh meter

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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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Kentfield, California, is located in a beautiful valley that butts up against Mt. Tamalpais near the Pacific Coast, in Marin County. Wind gusts off the Pacific frequently top 50 mph at the site. Add to this the location of the pool heating system on a public building that is near the San Andreas seismic fault, and you have a project with perhaps the most stringent design criteria in the US.

The most difficult aspect of the project was engineering a racking system that would conform to the required design criteria, span 12 feet and add less than 5% of the roof ’s original weight. In California, exceeding this 5% limit typically requires a seismic retrofit for the entire building. To meet the criteria, 0.125-inch square-tube steel—the thinnest that can be hot-dip galvanized—was specified for the racking substructure, and the collectors were located away from the edge of the roof to minimize wind loading. The final design was only a few hundred pounds under the maximum allowable weight. To verify this, the structural engineer had to calculate the weight of every bolt in the racking system.

Beyond the structural design, the system also needed to be aesthetically pleasing and maintain a 34° collector tilt. Heliodyne’s rack-mount system proved to be a relatively low profile and light mounting solution.

The overall project consists of two separate systems: a 65-collector array for heating a large lap pool and a 24-collector array for a dive pool. The collectors were placed on a narrow 300- foot long building with a curved center ridge. The array needed to be segmented into 19 separate subarrays. As a result, a detailed piping design was required for system optimization. One objective of this design was to create even flow through the arrays with limited use of balancing valves, which can be problematic and should be used only as a last resort. Another objective was to account for the large amount of expansion and contraction that occurs in long pipe runs that may be subjected to temperature swings of +/- 250°F. The longest direct pipe run is a 3-inch copper return line for the lap pool system that runs the entire length of the building. To accommodate this movement, several large expansion joints were installed throughout the piping system.

The college’s controls contractor designed the custom-built system controls that integrate the thermal systems with the primary building management system. The solar heating systems can be monitored and controlled along with the building’s other mechanical and electrical components. This allows for communication between the thermal system and the pool controls. For instance, set priorities can disable the pool heaters when the solar system is active at certain times. Solar priority is a common feature with residential pool controls, but it is not included in most commercial approaches.

"One significant advantage to having the thermal system fully integrated with the facility’s 'main brain' is that system malfunctions can be detected immediately. For example, if one of the solar pumps goes down, an alert can be sent to the maintenance staff via cell phone or email. The problem can be dealt with quickly, minimizing energy loss and potential further damage to the system."

Justin Weil, president, SunWater Solar

Overview

DESIGN SERVICES: SunWater Solar, sunwatersolar.com; Tipping Mar & Associates, structural engineering, tippingmar.com; Rumsey Engineers, mechanical engineering, rumseyengineers.com
LEAD INSTALLER: Adrian Dyer, foreman, SunWater Solar
DATE COMMISSIONED: July 2009
INSTALLATION TIMEFRAME: 60 days
LOCATION: Kentfield, CA, 37ºN
SOLAR RESOURCE: 5.17 kWh/m2/day, system yield is approximately 3.1 kWh/m2/day at 60% system efficiency
ANNUAL HEATING DEGREE DAYS: 2,567, base 65ºF
RECORD LOW TEMPERATURE: 20ºF
COLLECTOR AREA: 3,560 sq. ft.
AVERAGE ANNUAL PRODUCTION: 375 MWh

Equipment Specifications

COLLECTORS: 89 Heliodyne Gobi 410, 40 sq. ft. each
ARRAY: 19 subarrays total: 15 five-collector, 2 four-collector, 2 three-collector
STORAGE: 150,000-gallon dive pool and 145,000-gallon lap pool
HEAT EXCHANGERS: Three Young Cupronickel shell and tube, model F-604-AY-1P-CNT-B
PUMPS: 1.5 hp and 3 hp Bell and Gossett, 1510 Series
CONTROLS: Custom, integrated with building management system
FREEZE CONTROL: Closed-loop glycol
COLLECTOR INSTALLATION: Flat roof, modified bituminous membrane, Heliodyne rack-mount on custom fabricated steel substructure, 180º azimuth, 34º tilt
SYSTEM MONITORING: Two BTU monitors integrated with building management system and Heliodyne Web based monitoring system

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Sandwiched between Seattle and the Olympic Peninsula, picturesque Poulsbo, Washington, is home to the state’s first fullcapacity community solar project. The 75 kW array was developed by Washington Solar Incentives (WSI) and was installed by Frederickson Electric. WSI secured the host facility, negotiated all contracts, organized investors and oversaw the installation.

A first-in-the-nation Washington state incentive program that includes a community solar provision made the project at Poulsbo Middle School possible. The model allows community members to fund up to a 75 kW system on a public facility and receive a production incentive of $1.08/kWh. At the end of the incentive period in June 2020, the investors transfer ownership to the facility and are projected to have earned an average double-digit annual return.

The incentive requires the use of modules and inverter systems manufactured in Washington. The Silicon Energy modules feature frameless construction with a glass backsheet. The modules mount in a cascading fashion, which increases air circulation and effectively uses rainfall to clean the array. Silicon Energy developed the module racking system, which also serves as a raceway for the array conductors. The entire assembly is listed and has a Class A fire rating.

The 15 single-phase inverters take up an entire wall adjacent to the electrical service room. Inverter input and output wiring is organized in a gutter system surrounding the inverters and disconnects. The inverter outputs are combined five per phase in a dedicated distribution panelboard, which connects to the electrical service on the supply side to avoid backfeeding an existing GFI device on the main disconnect.

“It was an interesting challenge to design a 75 kW system with equipment manufactured in Washington. I’m pleased with the result, which combines very durable modules with an efficient inverter system.”

Hans Frederickson, Frederickson Electric

Overview

DESIGNER: Hans Frederickson, Frederickson Electric, fredelectric.com
LEAD INSTALLER: Bret Ortlieb, Frederickson Electric
PROJECT DEVELOPER: Rick Lander, Washington Solar Incentives, wa-solar-incentives.com
DATE COMMISSIONED: March 2011
INSTALLATION TIME FRAME: 60 days
LOCATION: Poulsbo, WA, 47.7°N
SOLAR RESOURCE: 3.7 kWh/m2/day
HIGH/LOW DESIGN TEMPERATURES: per solarabcs.org/permitting/map: 84°F/18°F
ARRAY CAPACITY: 74.1 kW
ANNUAL AC PRODUCTION: 72.2 MWh

Equipment Specifications

MODULES: 390 Silicon Energy SiE- 190, 190W STC, ±3%, 7.5 Imp, 25.3 Vmp, 7.9 Isc, 30.5 Voc
INVERTERS: 3-phase, 277/480 Vac service, 15 Power-One PVI-4.2- OUTD-US, 4.2 kW, 600 Vdc maximum input, 90–580 Vdc operating MPPT range, 200–530 Vdc full power MPPT range; Silicon Energy prewired inverter system assemblies with dc and ac disconnects
ARRAY: 13 modules per string (2,470 W, 7.5 Imp, 328.9 Vmp, 7.9 Isc, 396.5 Voc), two parallel strings per inverter (4,940 W, 15 Imp, 328.9 Vmp, 15.8 Isc, 396.5 Voc)
ARRAY INSTALLATION: Silicon Energy mounting hardware secured to custom-built galvanized steel rack. Aluminum racking components isolated from galvanized steel with rubber tape. 182° azimuth, 5° tilt
SYSTEM MONITORING (fredelectric.com/pms.html): Fat Spaniel inverterdirect monitoring with environmental sensors

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Ginger Allen’s home in the hills above Ashland, Oregon, was a site begging for solar. It had a relatively new roof, due south orientation, good pitch and a wide open solar window. A practitioner of passive solar design in her work as an architect, Ginger never had a client who utilized either solar thermal or PV. She purchased this home with the goal of getting solar on the roof to finally incorporate renewable energy into one of her projects.

Designing the PV system involved being mindful of real estate dedicated to a future thermal system. When the home was built in 2001, it was pre-plumbed for solar thermal with supply and return lines stubbed out of the roof. Twenty Evergreen 180 W modules nicely fit the available roof space.

Originally a Fronius IG4000 inverter was specified. Late in the process, Fronius USA offered the opportunity to install an IG Plus 3.8-1 beta unit. The inverter and datalogger are installed in the unfinished part of the home’s cool, dry basement. The first data dump from the datalogger to a laptop showed that the IG Plus 3.8-1 was operating well within expected parameters.

"Installation of the Fronius IG Plus is even easier than the previous models due to a two-part assembly. The bottom part is installed first and includes the mounting plate for the top part. The bottom also houses the electronics and disconnects common to all Fronius IG Plus machines. This two-part system makes lighter work of mounting the inverter."

- Eric Hansen, Electron Connection

Overview

DESIGNER: Bob-O Schultze, President, Electron Connection, electronconnection.com
LEAD INSTALLER: Eric Hansen, Oregon Limited Renewable Energy Technician, Electron Connection
DATE COMMISSIONED: June 2008
INSTALLATION TIMEFRAME: 3 days
LOCATION: Ashland, OR, 42º N
AVERAGE SOLAR RESOURCE: 4.9 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: -6º F / 92º F
ARRAY CAPACITY: 3.6 kW STC
AVERAGE ANNUAL AC PRODUCTION: 4.7 MWh

Equipment Specifications

MODULES: 20 Evergreen ES-180, +4%/-2%, 6.95 Imp, 25.9 Vmp, 7.78 Isc, 32.6 Voc
INVERTER: Fronius IG Plus 3.8-1, 3.8 kW, 600 Vdc maximum input, 230–500 Vdc MPPT range
ARRAY: 10 modules per series string (1,800 W STC, 6.95 Imp, 259 Vmp, 7.78 Isc, 326 Voc) with two paralleled strings (3,600 W STC, 13.9 Imp, 259 Vmp, 15.56 Isc, 326 Voc)
ARRAY INSTALLATION: Roof mount on composition shingle, Direct Power & Water Power Rail, 180º azimuth, 25º tilt
ARRAY COMBINER: groSolar Medium Pass-Thru Box, no series fusing
SYSTEM MONITORING: Fronius datalogger

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In April 2001, when the Pearl Brewery in San Antonio, Texas, shuttered its doors after 118 years of operation, many considered the buildings on the 22-acre site a prime target for demolition. Instead, the historic landmark was saved thanks to the vision of investor Silver Ventures and the site’s proximity to a planned 1.3-mile extension of the famous San Antonio River Walk. Providing a terminus for tourist barges, the renovated Pearl Brewery complex anchors the sustainably built urban revitalization project known as Rio Perla. At the heart of the project is the Full Goods Building, a former beer distribution warehouse redeveloped as mixed-use office, retail, restaurant and residential space. Renovated to LEED standards, the Full Goods Building is home to a 200 kW grid-connected PV array, the largest privately owned PV system in Texas.

Designed by Meridian Solar, the bulk of the PV generating capacity— 182 kW—is installed on a new TPO membrane roof using SCHOTT Solar ASE 300 W modules and the manufacturer’s proprietary SunRoof FS mounting system. TPO-compatible slipsheet material is installed under each array base plate. The locations and types of rooftop equipment and skylights changed over time or were not built as specified. This necessitated multiple engineering reviews to ensure that ballast and setback requirements were met and the manufacturer’s warranty remained intact.

An additional 18 kW of PV are installed as shade canopies at the building’s main and service entrances. Meridian Solar worked closely with architect Lake|Flato to custom design canopies using standard metal I-beams or trusses, ProSolar SolarWedge hardware and Sanyo bifacial 190 W HIT Double modules. A UL-listed polypropylene film separates the aluminum mounting baseplate from the building’s structural steel to prevent galvanic corrosion associated with the contact of dissimilar metals.

Due to space constraints, the inverters are located on the roof, installed on a custom elevated steel platform. SMA SunnyTowers simplify transportation to the roof but were primarily specified to facilitate the use of multiple module technologies. Within the SMA ST42, each inverter operates independently; this allows the Sanyo and SCHOTT modules to be wired to separate inverters on the same tower. CPS Energy, the municipal utility, required that Meridian Solar tighten the voltage trip points on each inverter, which was unexpected since smaller PV systems in its service territory interconnect using unmodified inverters.

CPS Energy provided partial funding for the PV system at the Full Goods Building and intends to study system performance. Therefore, the data acquisition solution provided by Draker Laboratories includes weather sensors and performance analytics. In addition, the high profile installation facilitates public outreach and education by means of an interactive kiosk with a large-screen display located in the Full Goods Building lobby. Information about the PV system at the Pearl Brewery, including an installation video, is available online at pearl.kiosk-view.com.

“When the utility told us to tighten voltage settings in the inverters, we complied—though we advised otherwise. After they saw the inverters nuisance tripping due to their own grid signature, they gave us permission to restore the factory settings. This not only proved our expertise, but also our commitment to customer service.”

Andrew McCalla, CEO, Meridian Solar

Overview

DESIGNER: Tommy Jacoby, VP of design, Meridian Solar, meridiansolar.com
PROJECT MANAGER: Jason Comstock, Meridian Solar
DATE COMMISSIONED: March 2009
INSTALLATION TIMEFRAME: 10 weeks
LOCATION: San Antonio, TX, 29.5°N
SOLAR RESOURCE: 5.4 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: 0°F / 95°F
ARRAY CAPACITY: 200.6 kW
AVERAGE ANNUAL AC PRODUCTION: 267 MWh

Equipment Specifications

MODULES, FLAT ROOF: 608 SCHOTT Solar ASE 300 DGF/50, 300 W STC, +4%/−4%, 5.9 Imp, 50.6 Vmp, 6.5 Isc, 63.2 Voc
MODULES, AWNINGS: 96 Sanyo HIP-190DA3, 190 W STC, +10%/-0%, 3.44 Imp, 55.3 Vmp, 3.7 Isc, 68.1 Voc
INVERTERS: 3-phase, 208 Vac service, four SMA ST42 (SunnyTower), 42 kW each, six SB7000US per tower, 600 Vdc maximum input, 250–480 Vdc MPPT range; one additional SMA SB6000US, 6 kW, 600 Vdc maximum input, 250-480 Vdc MPPT range
ARRAY, FLAT ROOF: Twenty 28 module subarrays with seven modules per string (2,100 W, 5.9 Imp, 354.2 Vmp, 6.5 Isc, 442.4 Voc) and four circuits per inverter (8,400 W, 23.6 Imp, 354.2 Vmp, 26.0 Isc, 442.4 Voc); two 24 module subarrays with eight modules per string (2,400 W, 5.9 Imp, 404.8 Vmp, 6.5 Isc, 505.6 Voc) and three circuits per inverter (7,200 W, 17.7 Imp, 404.8 Vmp, 19.5 Isc, 505.6 Voc)
ARRAY, AWNINGS: One 36 module subarray with six modules per string (1,140 W, 3.44 Imp, 331.8 Vmp, 3.7 Isc, 408.6 Voc) and six circuits per inverter (6,840 W, 20.6 Imp, 331.8 Vmp, 22.2 Isc, 408.6 Voc); two 30 module subarrays with six modules per string and five circuits per inverter (5,700 W, 17.2 Imp, 331.8 Vmp, 18.5 Isc, 408.6 Voc)
ARRAY COMBINER: Inverter integrated with 15 A fuses
ARRAY INSTALLATION, FLAT ROOF: SCHOTT Solar’s self- ballasted SunRoof FS mounting system on TPO membrane, 190° azimuth, 5° tilt
ARRAY INSTALLATION, AWNINGS: Professional Solar Products (ProSolar) SolarWedge hardware structurally attached to metal I-beams at main building entrance (10° tilt) and metal trusses at service entrance (15° tilt), 190° azimuth
SYSTEM MONITORING: Draker Laboratories Sentalis 1000PV monitoring package with public kiosk; utility installed revenue-grade PV meter

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To adhere to its Green Building Policy standard, the San Diego Community College District designed its new Career Technology Center at San Diego City College to achieve LEED Gold certification. The architectural features of the building dictate different module types split between a roof-mounted array and two vertical wall arrays. In addition to the drastic differences in array tilt angles, each array has multiple string configurations. The number of modules per string and strings per inverter vary to maximize the physical area available and avoid dummy modules to fill spaces. The arrays fit into an area dictated by the space, shading and architectural aesthetics to match other wall facades on the west wall and walkway clearances.

While the electrical design is not completely straightforward, the structural design of the vertical arrays presented the biggest challenge. The Unirac SunFrame racking system was used because it allows for a vertical orientation, conditional to properly designed structural spacing. Working closely with Unirac and Brian Spring of Brian Spring Engineering, Sullivan Solar Power ended up with a design that requires 3/8-inch tube steel run vertically up each wall on the west and east of the building, with a maximum spacing of 4 feet to provide the racking system support. Doublewide L-feet connect to the tube using two ¼-20 high-grade stainless steel screws; the SunFrame is then attached to the L-feet for module mounting. To prevent loosening and galling and to decrease potential corrosion, the bolts and screws are treated with a thread-locking compound, and holes in the tube steel are sealed with an electrometric polyurethane sealant.

The array installation provided its own set of challenges. The tallest vertical array tops out just over 120 feet from the existing grade. Since all work was done at the array locations, drilling the holes, attaching the racking and modules and making all the electrical connections required accurate planning and installation techniques. The installation team was divided into an inside crew and a lift crew. At the west wall, the back of the modules are accessible from inside, so the inside crew had the responsibility of wiring and grounding. They installed homerun cables and attached grounding lugs prior to module installation and returned after the modules were installed to complete the array wiring. The lift crew made all the mechanical connections from boom lifts—including tapping and installing the steel tube supports, mounting the Unirac SunFrame, installing the modules and cap strip and trimming the excess rail. Due to restricted access, the lift crew accomplished the array wiring and grounding for the east wall as the modules were installed. Moving the booms even small distances added another degree of difficulty for the lift crew.

“Establishing the installation process started slowly, because it was an incredibly arduous task. Once the crews figured out best practices, by day four they increased productivity and were mounting, grounding and connecting 40 modules daily. This project’s difficult design and installation made it all the more rewarding to see it turn out as nicely as it did.”

Quinn Laudenslager, Sullivan Solar Power

Overview

DESIGNER: Quinn Laudenslager, project manager, Sullivan Solar Power, sullivansolarpower.com
LEAD INSTALLER: Cesar Chaidez, project foreman, Sullivan Solar Power
DATE COMMISSIONED: May 2010
INSTALLATION TIME FRAME: 18 days
LOCATION: San Diego, CA, 32.7°N
SOLAR RESOURCE: Vertical arrays, 3.6 kWh/m2/day; roof array, 5.6 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: 29°F/78°F
ARRAY CAPACITY: 60.77 kW
ANNUAL AC PRODUCTION: 70,737 kWh projected

Equipment Specifications

MODULES, VERTICAL ARRAYS: 286 Sharp ND-N2ECU, 142 W STC, +10%/-5%, 7.11 Imp, 20.0 Vmp, 7.92 Isc, 24.9 Voc
MODULES, FLAT ROOF: 90 Sharp ND-224U1F, 224 W STC, +10%/-5%, 7.66 Imp, 29.3 Vmp, 8.33 Isc, 36.6 Voc
INVERTERS: 3-phase, 277/480 Vac service; nine SMA SB 7000US total, six for the vertical arrays, three for the roof-mounted array; 7 kW, 600 Vdc maximum input, 250–480 Vdc MPPT range
ARRAY, EAST VERTICAL: 16 modules per source circuit on Inverters 1–4, (2,272 W, 7.11 Imp, 320 Vmp, 7.92 Isc, 398.4 Voc) with three circuits per inverter (6,816 W, 21.33 Imp, 320 Vmp, 23.76 Isc, 398.4 Voc); one inverter with source circuits on both east and west vertical arrays
ARRAY, WEST VERTICAL: 18 modules per source circuit on Inverter 5, (2,556 W, 7.11 Imp, 360 Vmp, 7.92 Isc, 448.2 Voc) with three circuits (7,668 W, 21.33 Imp, 360 Vmp, 23.76 Isc, 448.2 Voc); and 20 modules per source circuit on Inverter 6, (2,840 W, 7.11 Imp, 400 Vmp, 7.92 Isc, 498 Voc) with two circuits (5,680 W, 14.22 Imp, 400 Vmp, 15.84 Isc, 498 Voc)
ARRAY, FLAT ROOF: 11 modules per source circuit on Inverters 1–2 (2,464 W, 7.66 Imp, 322 Vmp, 8.33 Isc, 402.6 Voc) with three circuits per inverter (7,392 W, 22.98 Imp, 322 Vmp, 24.99 Isc, 402.6 Voc); 12 modules per source circuit on Inverter 3, (2,688 W, 7.66 Imp, 351.4 Vmp, 8.33 Isc, 439.2 Voc) with two circuits (5,376 W, 15.32 Imp, 351.4 Vmp, 16.66 Isc, 439.2 Voc)
ARRAY INSTALLATION, VERTICAL: Unirac SunFrame attached to building face via steel-tube structure anchored into concrete, 180° azimuth, 90° tilt
ARRAY INSTALLATION, FLAT ROOF: Unirac Solar Mount on TPO membrane, 170° azimuth, 19° tilt
ARRAY COMBINERS: Inverter integrated with 15 A fuses
SYSTEM MONITORING: Fat Spaniel Inverter Direct PV2Web

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Being awarded the contract to install renewable energy systems on the world’s first zero energy climbing gym and one of the country’s first zero energy commercial buildings was a dream come true for Lighthouse Solar. To achieve the renewable energy goals that the facility’s owners and architect established, incorporating both solar electric and thermal systems was the optimal solution. Lighthouse Solar, through its affiliated division, Lighthouse Finance, owns the rooftop PV system and has entered into a PPA with the owners of the building to eliminate the upfront capital expenses.

The largest design challenge for the PV side of the project was determining the best mounting scheme to provide a system that would offset 100% of the building’s load. Energy modeling was used to forecast an annual demand of 120 MWh. A flush mounted system was the ideal choice for meeting the energy requirements and structural constraints. It also maximized the available financial incentives. The slightly lower output of a flush mounted system is easily offset by the ability to maximize the roof space and take full advantage of Xcel Energy’s solar rewards rebate of $2.00 per watt, capped at $200,000. Lighthouse Solar’s Lightgauge data monitoring system has since demonstrated that the PV system can cover 100% of the building’s electrical consumption.

The challenge for the solar thermal side of the project was determining the best way to integrate the solar storage tanks with three Rheem Marathon water heaters that were installed in two separate locations in the building. Due to limited space in the mechanical room where two Marathon water heaters are located, two Lumos 80-gallon single coil stainless steel storage tanks were selected for their tall, slender profile and small footprint. A third Lumos 80-gallon tank was installed in the laundry room, where it was integrated with the third Marathon water heater. This solar tank, with its less frequent use pattern, is recirculated with the Marathon water heater.

The two Marathons in the mechanical room are plumbed to all the bathrooms in the building, including the nine showers. Lighthouse Solar opted to forgo circulating these solar tanks because of the high demand on these units; in addition, the solar storage is sized in relation to the collector surface area on the roof. Once the building’s hot water patterns of use are determined, the system may be altered if recirculating is deemed effective.

“When we analyzed 10° and 20° tilt up systems, we found that the inter-row shading effects limited potential array capacity to 85 kW and 65 kW respectively. Systems in this range would not produce the required 120 MWh per year. Flush mounting the array allowed us to fit up to 130 kW of capacity in the same roof area. While a 99.9 kW array is sufficient to offset the projected consumption, the decision to flush mount the array makes future expansion to 130 kW an option.”

Chris Klinga, Lighthouse Solar

PV Overview

DESIGNER: Chris Klinga, general manager, Lighthouse Solar, lighthousesolar.com
CONSTRUCTION MANAGER: Jonathan Anderson, Lighthouse Solar
LEAD INSTALLER: Evan Goldstrand, Lighthouse Solar
DATE COMMISSIONED: August 2009
INSTALLATION TIME FRAME: 25 Days
LOCATION: Boulder, CO, 40°N
SOLAR RESOURCE: 5.5 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: -24°F/87°F
ARRAY CAPACITY: 99.9 kW
AVERAGE ANNUAL AC PRODUCTION: 119.5 MWh

PV Equipment Specifications

MODULES: 540 Lumos LS 185-M24, 185 W STC, +3%/-3%, 5.01 Imp, 37.1 Vmp, 5.27 Isc, 45.4 Voc
INVERTER: 3-phase, 208 Vac service, PV Powered PVP100 kW, 600 Vdc maximum input, 295–500 Vdc MPPT range
ARRAY: Three 180 module subarrays with 10 modules per string (1,850 W, 5.01 Imp, 371 Vmp, 5.27 Isc, 454 Voc) and six circuits per combiner (11.1 kW, 30.06 Imp, 371 Vmp, 31.62 Isc, 454 Voc)
ARRAY INSTALLATION: S-5! mounts with ProSolar rail on low slope standing seam metal roof;  220 modules at 270° azimuth, 1° tilt; 310 modules at 90° azimuth, 1° tilt; 10 modules at 180° azimuth, 10° tilt on awning in front of building
MONITORING: Lighthouse Solar’s Lightgauge data monitoring

Solar Thermal Overview

DESIGNER: Casey Wilson, technical sales engineer, Lighthouse Solar
LEAD INSTALLER: Brandon Mitchell, master plumber, Lighthouse Solar
DATE COMMISSIONED: July 2009
INSTALLATION TIME FRAME: 12 days
COLLECTOR ARRAY GROSS AREA: 165 square feet
AVERAGE ANNUAL PRODUCTION: 8.5 MWh

Thermal Equipment Specifications

COLLECTORS: Three Lumos 30 tube ETube collectors
HEAT EXCHANGER: Tank integrated 0.75 inch copper
PUMP: Grundfos 15–58
STORAGE: Three Lumos SST80-S 80-gallon single coil stainless steel tanks
CONTROLS: Lumos L3
FREEZE CONTROL: Closed loop glycol
COLLECTOR INSTALLATION: Roof mounted with custom powder coated steel support on a standing seam roof with S-5! mini clips, 180° azimuth, 40° tilt

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The array size for this desert home in Southern California is based on the maximum 108% of past usage, the state limit for rebate eligibility. Kaneka thin-film modules were selected for their low cost and aesthetic appeal as well as their performance in high temperature conditions. The property provided ample, comparatively flat, unshaded, south-facing land for a large ground mount system.

The project was relatively straightforward in terms of design and construction, but not without some challenges. One was the 775-foot distance from the array to the main panel, requiring significant trenching and careful conductor sizing. The array site itself presented some obstacles. Rocks had to be removed and a 3-foot slope from the northeast corner of the array to the southwest corner had to be overcome without grading.

The main challenge with a ground mount in this configuration is aesthetics. Lining the eight sections up took careful planning and execution. String lines, lasers and precise measurements were required to keep edges and heights uniform. A local fence company was contracted for part of the work. Its crew was more efficient at digging, pouring footings, setting posts and using standard schedule-40 galvanized pipe.

"The most unusual aspect of the design was the five module string size limitation, due to the Kaneka module voltage. This resulted in 82 strings, a necessity for more combiner boxes and additional attention to routing and wire management."

Mike Rango, SunWize

 

Overview

DESIGNER: Mike Rango, project engineer, SunWize Power Systems Division, sunwizesystems.com
LEAD INSTALLER: Mike Scott, installation foreman, SunWize Power Systems Division
DATE COMMISSIONED: October 2008
INSTALLATION TIMEFRAME: 20 days LOCATION: Sky Valley, CA, 33.8º N
AVERAGE SOLAR RESOURCE: 6.9 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: 13º F / 107º F
ARRAY CAPACITY: 24.6 kW STC
AVERAGE ANNUAL AC PRODUCTION: 50 MWh

Equipment Specifications

MODULES: 410 Kaneka G-SA060, 60 W STC, +10%/-5%, 0.9 Imp, 67.0 Vmp, 1.19 Isc, 91.8 Voc
INVERTERS: Four SMA SB6000US, 6 kW each, 600 Vdc maximum input, 250–480 Vdc MPPT range.
ARRAY: Two 100 and two 105 module subarrays: five modules per string (300 W, 0.9 Imp, 335.0 Vmp, 1.19 Isc, 459.0 Voc), 20–21 strings per inverter (6,000–6,300 W, 18.0–18.9 Imp, 335.0 Vmp, 23.8–25.0 Isc, 459.0 Voc)
ARRAY INSTALLATION: Ground mount, ProSolar Ground Trac, 180º orientation, 15º tilt
ARRAY COMBINER: Eight Blue Oak PV Products HBC12 with 3A fuses
SYSTEM MONITORING: SMA Sunny Portal

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