Project Profiles

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The Seattle Aquarium extends over the saltwater bay on Pier 59 in downtown Seattle. The historic landmark attracts almost 1 million visitors annually. In December 2013, NW Wind & Solar commissioned a 49.4 kW solar installation on the aquarium rooftop. The local utility, Seattle City Light, is sponsoring and will administer the Community Solar Program. The NW-based Bonneville Environmental Foundation provided technical support throughout the system design and installation.

While the Seattle Landmarks Preservation Board has special variances for solar, it required the aquarium to submit profiles, renderings and documents to ensure that the installation would be aesthetically pleasing and would not compromise the historical integrity of the landmark Seattle pier.  The board approved the design, in part thanks to the glass-on-glass Silicon Energy modules, whose appearance exceeded the design architect’s expectations.

The array is subject to high wind and saltwater mist. The double-glass design of the Cascade Series SiE200 module makes it a good choice for marine environments. Silicon Energy also offers an aluminum conduit upgrade for its powder-coated wire management and mounting system, specifically for marine installations. Anodized aluminum SunEarth Solar Strut provided added insurance that rust and corrosion would not compromise the looks of the landmark structure.

Interconnecting the system to a building that Seattle City Light’s downtown secondary network supplies proved to be a challenge. In most cases, commercial PV installations tie into the building’s electrical distribution system, which a utility radial distribution feeder line in turn supplies. However, a secondary network distribution system, interconnected to multiple radial feeder lines, feeds the Seattle Aquarium. The location of the aquarium’s electrical service—immediately adjacent to a secondary network transformer—is just about the worst-case scenario for the point of interconnection. A 12.47 kV feeder through the secondary network feeds the aquarium, and it has a 277/480 3-phase service, requiring a step-down transformer to interconnect the 208 Vac Silicon Energy inverters.

For this type of electrical service configuration, utilities may have concerns about backfeeding from the PV array to the secondary network. Bonneville Environmental Foundation, NW Wind & Solar and Seattle City Light sought the help of consultants from Schweitzer Engineering Laboratories to address the interconnection concerns. They determined that if the aquarium demand were to drop below 3 times the dc rating of the PV system, the system would require a minimum import relay controlling a contactor to disconnect the PV system and protect the secondary network from backfeeding. Designers configured the system to automatically disconnect if the aquarium’s instantaneous power demand ever drops below 150 kW, a rare situation that might occur if the seawater pumps shut down.

“Many stakeholders were involved in the Seattle Aquarium Community Solar Project. This led to several design and installation challenges that made for an exciting and memorable installation. The final product is durable, aesthetically pleasing and highly visible from Seattle’s waterfront. It’s a symbol of Washington’s ongoing commitment to local renewable energy.”

—Kevin Charap, division manager, NW Wind & Solar

“Community Solar demonstrates Seattle City Light’s commitment to meeting the energy needs of our customers in an environmentally sustainable manner and shows why we call ourselves ‘The Nation’s Greenest Utility.’”

—Sephir Hamilton, chief of staff, Seattle City Light

Overview

DESIGN FIRMS: NW Wind & Solar, nwwindandsolar.com; BonnevilleEnvironmental Foundation, b-e-f.org

INSTALLATION FIRM: NW Wind & Solar

DATE COMMISSIONED: December 2013

INSTALLATION TIME FRAME: 45 days

LOCATION: Seattle, WA, 47.6°N

SOLAR RESOURCE: 3.7 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 70°F 2% average high, 27°F extreme minimum

ARRAY CAPACITY: 49.4 kWdc

ANNUAL AC PRODUCTION: 54,023 kWh

Equipment Specifications

MODULES: 247 Silicon Energy Cascade Series SiE200, 200 W STC, +3/-3%, 7.8 Imp, 25.6 Vmp, 8.4 Isc, 30.6 Voc

INVERTERS: 277/480 Vac service, two Silicon Energy SiE3840 (3.3 kW at 208 Vac, 600 Vdc maximum input, 220–550 Vdc input voltage range), eight Silicon Energy SiE5300 (4.6 kW at 208 Vac, 600 Vdc maximum input, 220–550 Vdc input voltage range)

ARRAY: 14 modules per source circuit, typical (2,800 W, 7.8 Imp, 358.4 Vmp, 8.4 Isc, 428.4 Voc), 18 source circuits total, 49.4 kW array total

ARRAY INSTALLATION: Roof mount, composite shingle roofing, SunEarth 2.5-inch Black Anodized Solar Strut, Silicon Energy Cascade Series mounting system, 180° azimuth, 27° tilt

SYSTEM MONITORING: DECK Monitoring

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The Saint Louis Science Center - considered one of the top science museums in the US - has more than 750 interactive exhibits. The Science Center tapped Microgrid Solar, a PV installer headquartered in Saint Louis, to add solar to its list of displays.

The state of Missouri caps its solar rebate program at 25 kW, and Microgrid sized the Science Center's PV system to maximize the rebate. Microgrid installed the array on multiple low-slope roofs. It chose AET ballasted racking to minimize roof penetrations and added a few positive OMG PowerGrip attachments to meet structural and seismic considerations. In addition, wind loading for one of the subarrays, which is located adjacent to an interstate highway, required additional ballasting and mechanical attachments.

Microgrid selected Enphase microinverters for power conditioning because they enabled the array configuration to conform to both roof and programmatic restrictions. The two subarrays connect to a single ac combiner panel located on the rooftop. The system designer routed the aggregated inverter outputs to a ground-floor electrical room, where the utility point of interconnection is located.

Emphasizing the educational aspect of the PV system, the Science Center required that it include a way to connect visitors to the rooftop solar technology via a viewing area and an adjacent educational kiosk. The project is also part of the "Experience Energy" exhibit, and the public can access system production data on the Science Center's website.

"With more than a million visitors a year, we knew that the opportunity for impact from this project would be tremendous. We worked closely with not only the facility's staff, but also the educational and displays staff, to ensure that the arrays and accompanying displays would hit the mark."

—Rick Hunter, CEO, Microgrid Solar

Overview

DESIGNER: Tim Schulz, Microgrid Solar, microgrid-solar.com

LEAD INSTALLER: Mike Seger, Microgrid Solar

DATE COMMISSIONED: October 2013

INSTALLATION TIME FRAME: 10 days

LOCATION: Saint Louis, MO, 39°N

SOLAR RESOURCE: 4.8 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 95°F 2% average high, -2°F extreme minimum

ARRAY CAPACITY: 25 kWdc

ANNUAL AC PRODUCTION: 31,620 kWh

Equipment Specifications

MODULES: 100 SolarWorld Sunmodule Plus SW 250, 250 W STC, +5/-0 W, 8.05 Imp, 31.1 Vmp, 8.28 Isc, 37.8 Voc

INVERTERS: 3-phase 120/208 Vac service, 100 Enphase M215-60-2LL-S22-IG, 215 W continuous, 48 Vdc maximum input, 27–39 Vdc MPPT range, 25 inverters maximum per 3-phase 208 Vac 20 A branch circuit

ARRAY: Six ac branch circuits, 25 kWdc total

ARRAY INSTALLATION: Low-slope roof mount, white TPO membrane, AET Rayport B stainless steel ballasted racking, OMG PowerGrip roof attachments, 191° azimuth, 10° tilt

SYSTEM MONITORING: Enphase Envoy communications gateway, Enphase Enlighten web-based monitoring with educational kiosk

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Whole Foods Market has installed PV on several of its retail locations across the US. The recently commissioned 186 kW array at its new flagship store in the Domain shopping center in Austin, Texas, is the largest yet. Whole Foods chose to showcase this system by installing a third of the array on a mechanical screen that faces the store’s parking lot and is highly visible from the adjacent expressway. In the store’s lobby, a real-time display allows customers to view the system’s status as they check out. The eGauge monitoring system displays system parameters, including the amount of electricity that the PV system is generating compared to the total building’s energy consumption.

During the initial site survey, Freedom Solar Power noted that an existing rooftop mechanical screen rendered a large portion of the total roof area unusable for a roof-mounted array. The screen is composed of 10-by-10-by-½-inch galvanized steel structural members and rises 12 feet above the roof surface. To meet the client’s desire to maximize the overall capacity of the PV array while simultaneously making the array visible to its customers, Freedom Solar designed a custom racking solution that utilizes the structural elements of the mechanical screen. Freedom Solar replaced the metal decking with 248 Suniva 270 W modules.

Freedom Solar installed the balance of the array on the flat TPO membrane roof using the DynoRaxx Evolution fiberglass ballasted mounting system. The DynoRaxx product offered a clean solution, quick and flexible layout, and tool-free assembly. The fiberglass mount eliminates the requirement to electrically bond the mounting units together. DynoRaxx grounding clips bond the modules.

Freedom Solar procured the system’s nine SMA Sunny Tripower inverters from Gexpro; they are some of the first Tripower units installed in the US. The inverters offer several features that the team utilized during the project’s design and installation, including a wide operating MPPT window that allows for either 600 Vdc or 1,000 Vdc nominal arrays. While the inverters are listed for 1,000 Vdc applications, Freedom Solar chose a 600 Vdc maximum system voltage to avoid needing to procure and install 1,000 Vdc–rated BOS equipment, and then navigate the related Code requirements. The Tri-power inverters ship with a dc connection unit that enables a Code-compliant and clean installation, streamlines source-circuit aggregation and provides a disconnecting means for the inverter.

Freedom Power installed an SMA Cluster Controller in addition to the eGauge monitoring system. The unit offers centralized monitoring and control of up to 75 Tripower inverters. It integrates with SMA’s Sunny Portal web-based system to provide inverter-level system performance and diagnostic information and alarms. The SMA system enables both Freedom Solar and the building operators to monitor the system’s status performance data.

“The unique system we created for Whole Foods allowed us to fully utilize the building’s roof space and maximize array capacity. The company’s willingness to be creative let us design a system that will meet its 2015 goal of reducing the building’s energy consumption by 25% per square foot.”

Bret Biggart, managing director, Freedom Solar Power

Overview

DESIGNER: Chad Preece, chief operating officer, Freedom Solar Power, freedomsolarpower.com

LEAD INSTALLER: Adrian Buck, founder and chief installation officer, Freedom Solar Power

DATE COMMISSIONED: January 2014

INSTALLATION TIME FRAME: 35 days

LOCATION: Austin, TX, 30.3°N

SOLAR RESOURCE: 5.4 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 99°F 2% high, 23°F extreme minimum

ARRAY CAPACITY: 186.3 kWdc

ANNUAL AC PRODUCTION: 242,635 kWh

Equipment Specifications

MODULES: 690 Suniva OPT270-60-4-100, 270 W STC, +4.99/-0 W, 8.68 Imp, 31.2 Vmp, 9.15 Isc, 38.5 Voc

INVERTERS: 3-phase 277/480 Vac service, one SMA Sunny Tripower 15000TL-US (15 kW, 1,000 Vdc maximum input, 300–800 Vdc rated MPPT range, 150–1,000 Vdc operating MPPT range), seven SMA Sunny Tripower 20000TL-US (20 kW, 1,000 Vdc maximum input, 380–800 Vdc rated MPPT range, 150–1,000 Vdc operating MPPT range), one SMA Sunny Tripower 24000TL-US (24 kW, 1,000 Vdc maximum input, 450–800 Vdc rated MPPT range, 150–1,000 Vdc operating MPPT range); 179 kW inverter capacity total

ARRAY: 14 modules per source circuit, (3,780 W, 8.68 Imp, 436.8 Vmp, 9.15 Isc, 539 Voc), six source circuits per inverter typical (22,680 W, 52.1 Imp, 436.8 Vmp, 54.9 Isc, 539 Voc); 186.3 kW array capacity total

ARRAY INSTALLATION: Ballasted roof mount, TPO membrane roofing, DynoRaxx Evolution fiberglass mounting system; 442 modules at 160° azimuth, 10° tilt; 248 modules on custom cantilevered racking system, multiple azimuths and tilt angles

SOURCE-CIRCUIT COMBINERS: Nine SMA Connection Unit 600-US-10 combiners, 15 A fuses

SYSTEM MONITORING: eGauge EG3010 system monitoring, SMA Cluster Controller and SMA Sunny Portal web interface for remote inverter-level monitoring and control

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The 10 MWac Indianapolis Airport Phase I (Indy I) solar farm was commissioned in September 2013. The largest solar farm located on an airport site in the US, Indy I covers 75 acres of Indianapolis Airport property. Indianapolis Power & Light (IPL) is purchasing the solar energy that Indy I produces from General Energy Solutions USA (GES USA) via a 15-year power purchase agreement.

In addition to GES USA, the Indy I project team included Telamon, Johnson Melloh Solutions and Cenergy Power. The project created 140 temporary jobs during the construction phase, as well as 12 permanent O&M positions.

Cenergy Power and Solectria Renewables worked closely together to develop the optimal power conditioning and ac collection systems for the site. Indy I has a 1.25 dc-to-ac ratio. The power conditioning system includes 20 Solectria SGI-500XT inverters deployed on seven 1 MW and two 1.5 MW inverter pads. Nine 1,000 kVA 3-winding Cooper transformers with a 208 V Delta to 13.8 kV wye-grounded configuration are each connected to two 500 kVA Solectria inverters. Each of the  remaining two 500 kVA Solectria inverters has a corresponding 2-winding transformer with a 208 V Delta to 13.8 kV wye-grounded configuration.

The ac collection system includes two radial 5 MW daisy-chained feeders connected to 15 kV IEM switchgear. The switchgear has two 15 kV load-break interrupting switches that are manually operated for each feeder. The two 5 MW feeders are combined inside the switchgear and go to a 15 kV main draw-out circuit breaker equipped with two SEL 351S-7 relays for protection and control. One SEL 735 revenue meter monitors system output at the switchgear and is connected to a Draker SCADA unit.

Utility metering is accomplished through a pad-mounted 15 kV S&C Electric Company metering unit linked to the IPL remote terminal unit via radio communication. A pad-mounted 15 kW G&W Viper-ST recloser and a riser pole with a 15 kV pole-mounted gang-operated air-break switch provide interconnection to the IPL 13.8 kV line.

“Cenergy was able to successfully complete the Indianapolis Airport solar project ahead of schedule and below budget in great part due to the supportive efforts of municipal, airport and utility officials within the city of Indianapolis.”

Bill Pham, CEO, Cenergy Power

Overview

OWNER/DEVELOPER: General Energy Solutions USA, www.gesyw.com

CO-DEVELOPERS: Telamon, telamon.com; Johnson Melloh Solutions, johnsonmellohsolutions.com

PROJECT EPC: Cenergy Power, cenergypower.com

DATE COMMISSIONED: September 2013

INSTALLATION TIME FRAME: Approximately 160 days

LOCATION: Indianapolis, IN, 39.7°N

SOLAR RESOURCE: 4.6 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 89.6°F 2% average high, -7.6°F extreme minimum

ARRAY CAPACITY: 12.569 MWdc

ANNUAL AC PRODUCTION: 17,057 MWh

Equipment Specifications

MODULES: 44,128 total; 19,800 General Energy Solutions (GES) 7C00-6C295, 295 W STC, +5/-0 W, 8.32 Imp, 35.47 Vmp, 8.95 Isc, 46.20 Voc; 17,776 GES 7C00-6C290, 290 W STC, +5/-0 W, 8.19 Imp, 35.40 Vmp, 8.82 Isc, 45.5 Voc; 6,552 Sharp ND-240QCJ, 240 W STC, +5/-0%, 8.19 Imp, 29.3 Vmp, 8.75 Isc, 37.5 Voc

INVERTERS: 20 Solectria Renewables SGI-500XT, 500 kW rated output, 600 Vdc maximum input, 300–500 Vdc MPPT range, external transformer, 3-phase 208 Vac output; 13.8 kV point-of-utility connection

ARRAY: 20 subarrays; GES modules: 11 modules per source circuit (GES 7C00-6C295: 3,245 W, 8.32 Imp, 390.2 Vmp, 8.95 Isc, 508.2 Voc), 3,416 GES source circuits total, 12–16 combiners per inverter terminated at inverter-integrated 600 Vdc breakers; Sharp modules: 13 modules per source circuit (3,120 W, 8.19 Imp, 380.9 Vmp, 8.75 Isc, 487.5 Voc), 504 Sharp source circuits total, 12–16 combiners per inverter terminated at inverter-integrated 600 Vdc breakers; 12.569 MWdc array capacity total

ARRAY INSTALLATION: Ground mount, Schletter FS System racking, 180° azimuth, 25° tilt

SOURCE CIRCUIT COMBINERS: 299 SolarBOS, models CS-06-15-N3, CS-08-15-N3, CS-10-15-N3, CS-12-15-N3 and CS-14-15-N3

SYSTEM MONITORING: Draker PV 2000 with environmental monitoring, cellular modem at the switchgear pad, and wireless network switch and media converter at each inverter pad

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San Diego Eco Rentals is a provider of eco-friendly vacation rentals. Its homes are located in some of San Diego’s trendiest neighborhoods and offer the style and comfort expected from luxury accommodations. Each home features a PV system, LED lighting, a rainwater collection system, a graywater irrigation system and access to a free electric vehicle charging station, among many other sustainable features.

Sullivan Solar Power designed and installed a PV system on the company’s newest property, a four-bedroom, two-bath, Spanish-style duplex in the University Heights neighborhood. The 1,250-square-foot roof is split between two stories. The array spans the entire upper 500-square-foot roof, leaving the lower, larger space available as a rooftop deck or for future solar installations.

Sullivan Solar Power considered it essential to use a module-level power electronics system to mitigate the effects of a large evergreen tree nearby that provides shade and privacy for one of the units. Based on owner input and the system’s installation and monitoring requirements, Sullivan Solar selected SMA America’s new Sunny Boy 240-US microinverter system for the project. The inverters’ cabling system eliminates the need for a trunk-and-branch cabling scheme and provides preassembled ac plugs and connection cables that the crew installed in a daisy-chain configuration.

“The owner is passionate about reducing his and his renters’ carbon footprint. Because this is an investment property, he was also very concerned with equipment reliability. Choosing PV components manufactured by companies with long business histories, strong financials and respected service reputations was an important consideration for him.”

Sean Mazelli, Sullivan Solar Power

Overview

DESIGNERS: Sean Mazelli, project developer; Rick Rios, PV design engineer and project manager; Sullivan Solar Power, sullivansolarpower.com

LEAD INSTALLERS: Adam Gapen, foreman; Chris Johnson, lead installer; Sullivan Solar Power

DATE COMMISSIONED: February 2014

INSTALLATION TIME FRAME: 3 days

LOCATION: San Diego, CA, 32°N

SOLAR RESOURCE: 5.6 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 79°F 2% average high, 41°F extreme minimum

ARRAY CAPACITY: 4,410 Wdc

ANNUAL AC PRODUCTION: 7,140 kWh

Equipment Specifications

MODULES: 18 Kyocera KD245GX-LFB2, 245 W STC, +5/-0%, 8.23 Imp, 29.8 Vmp, 8.91 Isc, 36.9 Voc

INVERTERS: Single-phase 120/240 Vac service; 18 SMA Sunny Boy 240-US, 240 W, 45 Vdc maximum input, 23–32 Vdc MPPT range, 240 Vac output; two SMA Sunny Multigate-US electrical/communication interfaces 15 A circuit breakers

ARRAY: One microinverter per module, two ac branch circuits (one 11 module and one 7 module), 4,410 W total

ARRAY INSTALLATION: Torched-down roofing, Unirac Solar Mount with tilt legs, 180° azimuth, 15° tilt

SYSTEM MONITORING: Two SMA Sunny Multigate-US (module-level communications), SMA Sunny Portal web interface

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The 7.4 MWdc/4.999 MWac Somers Solar Center is located on approximately 75 acres of privately held farmland in Somers, Connecticut. Upon commissioning in late December 2013, the Somers Solar Center became the largest solar facility in New England, producing enough electricity to supply approximately 1,400 homes. Connecticut Light & Power purchases the electricity generated under a 20-year power purchase agreement. The property owner receives annual lease payments in return for housing the project.

HelioSage Energy and CleanPath Ventures developed the project; and Prime Solutions, an energy-engineering firm headquartered in New Milford, Connecticut, was the EPC contractor. Designing the system required a coordinated effort with Connecticut Light & Power. Prime Solutions also collaborated with the Connecticut Department of Energy and Environmental Protection (DEEP) to develop a detailed storm water management plan.

The site includes numerous rolling hills, and a protected watershed bifurcates the area. The project team had to address the resulting technical hurdles to ensure that the system would meet its projected production numbers and to satisfy restrictions imposed by several governing agencies. For example, a directive from the Connecticut Siting Council limited tree trimming, and DEEP’s storm water management plan imposed additional restrictions related to grading and soil disturbance.

Teams from Prime Solutions and Array Technologies collaborated to develop a site plan with three separate arrays that utilizes the terrain-following capabilities of the tracking system. This design allowed Prime Solutions to optimize the system’s production capacity, minimize shading from the protected tree line and effectively level the system to minimize interrow shading. Array Technologies’ DuraTrack HZ single-axis trackers were critical in allowing Prime Solutions to design a system with minimal impact on the existing site topography while ensuring that the system met required production values.

Due to short design and construction time lines and regulatory constraints, Prime Solutions recommended a capacity for the project of just under 5 MWac. This eliminated the necessity for a lengthy transmission study that ISO New England would have required. The resulting 4.999 MWac system size allowed a faster approval time by Connecticut Light & Power and ISO New England. The final power conditioning system design includes four 1 MW AE Solar Energy (AESE) Open TX PowerStations with two AE 500TX inverters per skid. An additional 999 kW AESE Open NX PowerStation utilizes three AE 333NX inverters. A 1,000 kVA 480/277 to 23 kV transformer is integrated with each of the five power stations.

“Prime Solution’s successful design and on-time completion of the Somers Solar Center project is a shining example of our team’s technical expertise and execution capabilities in delivering utility-scale projects.”

William May, CEO, Prime Solutions

Overview

EPC: Prime Solutions, primesolutions-inc.com

DEVELOPERS: HelioSage Energy, heliosage.com; CleanPath Ventures, cleanpath.com

DATE COMMISSIONED: December 2013

INSTALLATION TIME FRAME: 180 days

LOCATION: Somers, CT, 41.6°N

SOLAR RESOURCE: 4.4 kWh/m2/day

ASHRAE DESIGN TEMPERATURES:  90°F 2% average high, -4°F extreme minimum

ARRAY CAPACITY: 7.4 MWdc, 4.999 MWac

ANNUAL AC PRODUCTION: 10,557 MWh

Equipment Specifications

MODULES: 23,150 Kyocera KD320GX-LFB, 320 W STC, +5/-3%, 7.99 Imp, 40.1 Vmp, 8.6 Isc, 49.5 Voc

INVERTER STATIONS: 23 kV medium-voltage interconnection, five power stations total with one 1,000 kVA 480/277 to 23 kV transformer per station; four AE Solar Energy 1 MW Open TX PowerStations with two AE 500TX inverters per power station (500 kW, 600 Vdc maximum input, 310–595 MPPT range, 3-phase 480 Vac output); one custom AE Solar Energy 999 kW Open NX PowerStation with three AE 333NX inverters (333 kW, ±600 Vdc maximum input, ±330–±550 Vdc MPPT range, 3-phase 480 Vac output); 4.999 MWac inverter capacity total

ARRAY: 10 modules per source circuit (3,200 W, 7.99 Imp, 401 Vmp, 8.6 Isc, 495 Voc), 13–16 source circuits per combiner, 15 combiners per inverter (typical), 7.4 MWdc array capacity total

ARRAY INSTALLATION: Tracked ground mount, 32 Array Technologies DuraTrack HZ Solar Trackers, single-axis, gear drive, one 1.5 HP motor per tracker, algorithm with GPS input tracking method

SOURCE CIRCUIT COMBINERS: 150 Eaton SC24P, NEMA 4, 15 A fuses

SYSTEM MONITORING: DECK Monitoring with weather station, inverter-mounted Shark production meters and ION utility generation meter

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Jeff Spies, the senior director of business development at Quick Mount PV, contracted American Solar to install a PV system at his residence. The system employs one of the first SMA 4000TL-US inverters installed in the US. This non-isolated inverter features two MPP trackers and a Secure Power Supply function that provides up to 12 amps of backup power at 120 Vac, given that there is sufficient solar irradiance

American Solar’s licensed roofing contractor division refurbished the 16-year-old roof and relocated plumbing and gas vent stacks to create space for the array. The SMA 4000TL-US’s dual MPP channels and wide operating MPPT range made it possible to locate a 3,120 W array on a southeast-facing roof and a 1,560 W array on the southwest-facing garage roof.

To ensure that the home’s tile roof would last the 30-year life of the array, American Solar installed a 90# mineral-surface rolled roofing underlayment. Tru-Flow drain-through battens speed rainwater drainage, which extends underlayment life. Ventilation upgrades include Boral vented eave risers and O’Hagin roof vents. The crew used Quick Mount PV’s Quick Hook flashed tile mounts in conjunction with IronRidge Standard mounting rail, providing for an attractive finished appearance. (For details on similar installations, see “Tile Roof Applications,” SolarPro magazine, October/November 2013.)

“Since I work for the leading manufacturer of code-compliant flashed PV mounts, I understand the long-term cost benefits of installing a new roof under the array. When choosing an installer, I looked no further than American Solar. The company did a great job installing a system that offers excellent performance.”

Jeff Spies, Quick Mount PV

Overview

DESIGNER: Paul Swanson, American Solar, americanpv.com

LEAD INSTALLER: Robert Hileman, American Solar

DATE COMMISSIONED: July 26, 2013

INSTALLATION TIME FRAME: 3 days

LOCATION: Chandler, AZ, 33.3°N

SOLAR RESOURCE: 6.5 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 109°F 2% average high, 34° extreme minimum

ARRAY CAPACITY: 4.68 kWdc

ANNUAL AC PRODUCTION: 7,500 kWh (projected)

Equipment Specifications

MODULES: 18 LG Electronics LG260S1C-G3, 260 W STC, +3/-0%, 8.61 Imp, 30.2 Vmp, 9.2 Isc, 37.9 Voc

INVERTER: Single-phase 120/240 Vac service, one SMA Sunny Boy 4000TL-US with Secure Power Supply, 4 kW, 600 Vdc maximum input, two MPP trackers, 175–480 Vdc rated MPPT range, 125–500 Vdc operating MPPT range

ARRAY: Two orientations. SW array: one six-module source circuit (1,560 W, 8.61 Imp, 181.2 Vmp, 9.2 Isc, 227.4 Voc); SE array: one 12-module source circuit (3,120 W, 8.61 Imp, 362.4 Vmp, 9.2 Isc, 454.8 Voc); 4.68 kWdc array total

ARRAY INSTALLATION: Monier S-Tiles installed on Tru-Flow drain-through battens, 90# mineral-surface rolled roofing underlayment, Quick Mount PV Quick Hook flashed tile mounts, IronRidge Standard rail; SW array: 223°azimuth, 18° tilt; SE array: 133° azimuth, 18° tilt

SYSTEM MONITORING: SMA Sunny Webbox, SMA Sunny Portal web interface

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The Harvest Hill Golf Course underwent extensive renovations that were completed in May 2013, including the construction of a new clubhouse, two cart houses and a tournament pavilion. To help reduce facility operations costs, Frey Electric installed a 37.44 kW PV array on the two new cart houses. The array is expected to offset 20% of Harvest Hill’s annual energy consumption. While the PV system was not part of the project’s initial design, the arrays were relatively easy to integrate with the cart house buildings.

The 144-module array is split across two 12:12 metal standing-seam roofs with azimuths of 240° and 259°. The installers flush-mounted the array with S-5! Mini Clamps and PV Kits, so roof penetrations were not necessary. The steep roof angle presented both challenges and a performance advantage. The crew needed to use a two-person basket lift during the array installation. They pre-assembled S-5! Kits in the shop to reduce field labor and minimize the potential loss of hardware off the roof during installation. At the jobsite, the installers quickly positioned the assemblies, installed and torqued them per specification. The steep roofs offer a performance benefit as the arrays shed snow easily during the winter months, which increases overall energy production.

Each roof has sufficient area for the installation of 72 modules. The corresponding array layouts are well matched for integration with four 10 kW Fronius IG Plus Advanced inverters. The designers initially considered microinverters; however, due to the steep roof pitch and difficult access, they chose string inverters to eliminate the need to access the roof in the event of an inverter failure.

The crew installed Wiley ACE 3-pole transition boxes on each roof to make the transition from PV Wire to THHN conductors. They connected three individual PV source circuits to each Fronius IG Plus Advanced inverter via its integrated fused combiner. Inside each cart house, the ac output of two inverters is combined in a load center and then connected to a dedicated PV generation meter. The combined output from one cart house runs underground to the other cart house. A third load center combines the output of all four inverters. A fusible disconnect protects this single circuit, which terminates on the load side of a 150 kVA 480/208 service distribution transformer. This was the most economical point of connection, since the existing 208 V panels are located in other buildings.

The crew installed a Fronius Datalogger Web unit and tested it using a WLAN Wi-Fi stick antenna. However, the metal building surrounding the WLAN stick prevented the inverters from receiving an adequate signal. The installers then swapped out the antenna with a Fronius External Antenna LAN stick mounted on the outside of the building and connected to the Datalogger Web using a USB extension cable approximately 80 feet long. Excessive power loss over the USB cable prevented this second configuration from working. Ultimately, the crew moved the Datalogger Web closer to the external antenna and ran a Cat 5 cable to the first inverter.

“Initially, working from lifts added a level of difficulty for the installation crew, but the final product came out well. While the array orientations are not ideal, energy production has been above the projected values.”

Deborah Zarbo, Frey Electric

Overview

DESIGNER: Deborah Zarbo, engineer, Frey Electric, frey-electric.com

LEAD INSTALLER: Ray Szopinski, electric site foreman, Frey Electric

DATE COMMISSIONED: July 2013

INSTALLATION TIME FRAME: 18 days

LOCATION: Orchard Park, NY, 43°N

SOLAR RESOURCE: 4.2 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 86°F 2% average high, −4°F extreme minimum

ARRAY CAPACITY: 37.44 kWdc

ANNUAL AC PRODUCTION: 36,262 kWh

Equipment Specifications

MODULES: 144 Helios Solar Works 6T 260, 260 W STC, +3/-0%, 8.46 Imp, 30.84 Vmp, 8.9 Isc, 37.73 Voc

INVERTERS: 3-phase 120/208 Vac service, four Fronius IG Plus Advanced 10.0-3 UNI Delta, 10 kW, 600 Vdc maximum input, 230–500 Vdc MPPT range

ARRAY: 12 modules per source circuit (3,120 W, 8.46 Imp, 370.1 Vmp, 8.9 Isc, 452.8 Voc), three source circuits per inverter (9,360 W, 25.4 Imp, 370.1 Vmp, 26.7 Isc, 452.8 Voc), 37.44 kW array total

ARRAY INSTALLATION: Roof mount, standing-seam metal roofing, S-5! Mini Clamps with S-5! PV Kits; 72 modules with 240° azimuth, 72 modules with 259° azimuth, 45° tilt

ARRAY SOURCE-CIRCUIT COMBINERS: Inverter integrated, 15 A fuses

SYSTEM MONITORING: Fronius Datalogger Web with external LAN antenna

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Before the launch of Ontario’s feed-in tariff (FIT) program, the owner of Vine Fresh Produce, a southern Ontario greenhouse operator, explored installing a net-metered PV system at its facility. When the FIT went into effect, the program offered favorable financial returns compared to a net-metered system. The company received a 2 MWac FIT contract and selected Sentinel Solar as the project’s EPC. The 2.3 MWdc 3-phase system utilizes 9,294 Enphase microinverters. It is the largest rooftop installation under the Ontario FIT program and the largest Enphase microinverter installation to date.

The design of the greenhouses’ saw-tooth rooflines shades the bottom portion of each roof section during certain times of the day and the year. Due to this site limitation, a microinverter system was the optimal approach to mitigate the shading impact on system production. In addition, the facility owner was interested in a distributed system architecture that would prevent significant energy production losses due to equipment failures.

Sentinel Solar worked with Vine Fresh Produce to design an array racking and mounting system that is integrated with the roof structure of the greenhouses. The design replaces glazing panels with modules to minimize materials and reduce additional load on the structures. The unique PV-mounting approach provides full access to each module and microinverter from inside the greenhouses for safe and streamlined O&M activities.

The system’s racking, modules and microinverters are all manufactured in Ontario. The system pairs Jinko 250 W modules with Enphase M215 microinverters. AC branch circuits consisting of 24 inverters (typical) are installed in a center-feed configuration to minimize voltage rise in the Enphase Engage cabling system. The array is composed of twenty 100 kWac subsystems. Each subsystem has 20 branch circuits (typical) that terminate in 400 A panelboards. The ac system is then aggregated in two 1,200 A distribution panels before interconnecting with the site’s 600 Vac 3-phase service.

The Vine Fresh Produce O&M staff will provide ongoing monitoring and maintenance of the solar asset. The installation’s low dc system voltage and module-level monitoring are both very attractive to the facility’s owner, as is the ability to monitor the system remotely and to accurately pinpoint any performance issues.

“For such a large, complex rooftop installation, we knew that being able to track the system’s performance at the module level would be beneficial. This was a key consideration in choosing the Enphase system for the Vine Fresh Produce project.”

—Andy Bennis, VP of sales and marketing, Sentinel Solar

Overview

DESIGNER: Adam Webb, president, Sentinel Solar, sentinelsolar.com

PROJECT EPC: Sentinel Solar

DATE COMMISSIONED: May 2013

INSTALLATION TIME FRAME: 6 months

LOCATION: Strathroy, Ontario, Canada, 42.95°N

SOLAR RESOURCE: 4.3 kWh/m2/day

DESIGN TEMPERATURES: 79°F average high, −1°F record low

ARRAY CAPACITY: 2.3 MWdc

ANNUAL AC PRODUCTION: 2,540 MWh

Equipment Specifications

MODULES: 9,294 Jinko Solar 250W Poly, 250 W STC, +3/-0%, 8.2 Imp, 30.5 Vmp, 8.8 Isc, 37.6 Voc

INVERTERS: 3-phase 600 Vac service, 9,294 Enphase M215-60-2LL-S22-NA, 215 W, 45 Vdc maximum input, 22–36 Vdc MPPT range, 208 Vac output

ARRAY: 24 microinverters per ac branch circuit (typical), center-feed branch circuit configuration, 20 branch circuits per 100 kWac subarray (typical), one 400 A panelboard for each 100 kWac subarray, two 1,200 A distribution panels

ARRAY INSTALLATION: Greenhouse roof mount, custom racking, 180° azimuth, 25° tilt

SYSTEM MONITORING: 20 Enphase Envoy communication gateways, Enphase Enlighten web-based monitoring

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The Chalmers Residence is located on the bay side of Delaware’s Fenwick Island, an area known for its ocean views and high-end homes. The PV project’s biggest initial challenge was balancing aesthetics and performance. Sungevity designed the system and financed it through its residential leasing program. SunnyMac Solar was responsible for system installation.

The arrays are installed on three roof surfaces with two orientations. The designers selected Power-One Aurora Uno inverters, which feature two independent MPPT channels, to maximize system performance.

Because the home has vaulted ceilings, the installers ran all conduit on the exterior of the home and hid it as much as they could. To minimize the visual impact of the raceway system, they installed a SolaDeck junction box on each roof surface. Strategically placed rooftop conduits feed the output circuits of the four separate strings into a single 1-inch EMT conduit. This conduit is tucked out of sight as much as possible and terminates at the system’s inverters.

The home is elevated on wooden piles. A strut system under the home supports the inverters, ac load center and associated monitoring equipment. Because the service panel is in an inaccessible interior location, the designers called for a line-side utility interconnection. They rerouted service conductors to allow for a Code-compliant connection to the combined inverter-output circuit.

They installed the Locus Energy LGate 101 monitoring system box adjacent to the inverters and connected it to each inverter via Cat 5 cables. The monitoring system uses power line communication to transmit inverter data to an Ethernet bridge connected to the client’s wireless router. The LGate 101 provides revenue-grade production metering, load metering and inverter-level monitoring.

“The challenges presented by the home’s multiple roof surfaces and orientations, as well as the requirement to minimize the visual impact of the exterior-mounted raceways, required a high attention to detail. We consider the Chalmers residence system to be SunnyMac’s signature residential installation.”

— Matthew Macfadden, SunnyMac Solar

Overview

DESIGN FIRM: Sungevity, sungevity.com

LEAD INSTALLER: Matthew Macfadden, SunnyMac Solar, sunnymacsolar.com

DATE COMMISSIONED: October 2013

INSTALLATION TIME FRAME: 5 days

LOCATION: Fenwick Island, DE, 38.5°N

SOLAR RESOURCE: 4.5 kWh/m2/day

ASHRAE DESIGN TEMPERATURES: 91°F 2% average high, 7°F extreme minimum

ARRAY CAPACITY: 7.35 kWdc

ANNUAL AC PRODUCTION: 8,800 kWh

Equipment Specifications

MODULES: 30 ET Solar ET-P660245BB, 245 W STC, +3/-0%, 8.13 Imp, 30.14 Vmp, 8.73 Isc, 37.27 Voc

INVERTERS: Single phase 120/240 Vac service, one Power-One Aurora Uno PVI-3.0-OUTD-S-US (3 kW, 600 Vdc maximum input, 160–530 Vdc MPPT range), one Power-One Aurora Uno PVI-3.6-OUTD-S-US (3.6 kW 600 Vdc maximum input, 120–530 Vdc MPPT range)

ARRAY: PVI-3.0-OUTD-S-US: seven modules per source circuit (1,715 W, 8.13 Imp, 211 Vmp, 8.73 Isc, 260.9 Voc), two source circuits total (3,430 W, 16.3 Imp, 211 Vmp, 17.5 Isc, 260.9 Voc); PVI-3.6-OUTD-S-US: eight modules per source circuit (1,960 W, 8.13 Imp, 241.1 Vmp, 8.73 Isc, 298.2 Voc), two source circuits total (3,920 W, 16.3 Imp, 241.1 Vmp, 17.5 Isc, 298.2 Voc); 7.35 kW array total

ARRAY INSTALLATION: Roof mount, composition shingle roofing, IronRidge XLR racking; eight modules with 226° azimuth, 23 modules with 136° azimuth, 27° tilt

SYSTEM MONITORING: Locus Energy LGate 101, inverter-level monitoring

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