Project Data

End-User: NJ Public Health Environmental Agricultural Laboratory

Installer: Hatzel Buehler, Inc.

Location: Trenton, New Jersey

Date of install: October 2006

Size of system in kW: 175kW

Energy produced since installation: 1,800 MWh

Special Challenges Met: Construction Schedule

Architect: HOK

Project Brief

Table of Contents:

1. Introduction

2. Technical Design Approach

    2.1 System Performance

    2.2 Array Mounting Structure

    2.3 PV Modules

    2.4 Inverters

    2.5 Balance of System

    2.6 Monitoring System

The following submittal allows for the installation of QTY(1000) 175W MonoCrystalline SolarWorld Modules on the roof of the New Jersey Public Health, Environmental and Agricultural Laboratory at a tilt angle of 5 degrees using SunLink mounting hardware. It is important to confirm that the roof structure of the NJPHEAL is capable of supporting a distributed load of up to 7lbs./sf additional to the code compliant snow load. It is in this safety margin of structural performance that a self ballasted mounting system which tilts the modules at 5 degrees can be mounted without penetrations to the roof. Based on a 100 MPH 3 second gust, and exposure class B the preliminary dead loads of the non-penetrating PV systems for the 88’ high upper roof, the 64’ high lower roof and 31’ high Pavillion roof are 6.7 PSF, 6.1 PSF, and 5.0 PSF respectively.

Electrically, this submittal departs from the construction documents in the following ways:

Where the construction documents call for two separate inverters for the upper roof with 0 degree sloping modules and the lower roof with 13 degree sloping modules, we have proposed one Satcon 135kW Inverter for both roofs which are both proposed at 5 degrees- upper roof, (63kW SW175s) and lower roofs (79.8kW SW175s).

Where the construction documents call for separate inverters for the pavillion array, we have proposed one Satcon 30kW Inverter for the proposed 32.2kW array mounted at 5 degrees on SunLink.

While our 1-Line diagrams show separate AC disconnects for the 30kW and the 135kW inverters, the construction documents show a pv system master ac disconnect. This solution may be adopted if preferred over separate ac disconnects. We note the use of the inverters’ integrated switches in the construction documents.

The monitoring system is not shown on our 1-Line diagram and we propose to conform to the construction docs.

3.1. System Performance

PV system performance is influenced by a wide variety of factors including system installation practices, wire sizing, weather conditions, inverter loading, orientation towards south, available sunlight, etc. As such, we can predict system performance with a high level of accuracy. However the model used does include these factors. The charts below show expected AC output from the proposed system given the following de-rate assumptions:

Hourly weather data from the National Renewable Energy Laboratory’s 239-station TMY2 database and a PV performance model based on a Sandia National Laboratories’ Algorithm. (technical references are available upon request.) are used to estimate monthly and annual AC energy production (kWh) for a crystalline silicon PV system. 

Notes on performance estimates. The analysis of system performance assume the following:

1. Insolation data is based on averages – actual insolation will vary.

2. Thermal and electrical coefficients for the modules as provided by the manufacturer.

3. There is no significant shading of the system.

4. Actual energy production will vary according to insolation, temperature, shading, age of the array and many other factors.

5. These figures are for estimation purposes only and are not a guarantee. Comparisons between systems should be made based on AC rating, orientation, array operating temperature and tilt of the system as opposed to predicted output.

3.2. Array Mounting Structure – Sunlink

TurtleEnergy will mount the PV array on the roof using Sunlink mounting assemblies. This creates an interlocking structure that requires ballasting and no roof penetrations. Our experience with flat roof PV systems suggests avoiding laying PV modules flat or directly on top of the roof for the following reasons:

· Higher Energy Capture – Simply by facing the sun more directly, a tilted array captures more energy. Even a 5-degree tilt generates up to 4% more energy than a flat array.

· Cooler Operating Temperature – A tilted array allows natural convection to cool the array, allowing modules to operate more efficiently and increases the equipment life. Flat arrays with less air circulation operate at higher temperatures and produce less power – just when it is needed for peak building loads.

· Improved Roof Drainage – An elevated structure also allows for better roof drainage. Water and air can circulate freely over the roof surface, just as intended by roofing manufacturers.

· Easy Roof Access – This mounting approach allows easy access to roof surface for maintenance or repairs of the surface or the array. For minor repairs, panel assemblies can be left in place or tilted up out of the way.

We are proposing that all PV modules be tilted at 20° and that the mounting structure be elevated above the roof surface to allow for roof access and air circulation. All mounting structures we supply and install utilize heavy duty,

long lasting materials. PV modules are supplied with factory-fabricated frames (for longer life, and greater module strength). These frames are mechanically attached to the aluminum support structure using stainless steel fasteners.

For this project, the Solar World 175W modules will be panelized in groups of 3 & 4. We have grouped the modules to allow for access to the roof and other equipment. The system is designed to add less than 10 pounds per square foot of roof loading.

Your building is a valuable asset. SunLink helps keep it that way with the most roof-friendly PV mounting system in the industry.

non-penetrating

Together with your engineers and permitting authorities, SunLink® designs the best method to secure the array to your building. Most situations can be successfully addressed without roof penetrations. But in those cases where they are required, the SunLink system needs only a fraction of those needed by competing brands.

quick and easy roof access

Only SunLink offers Tilt-Access™, a unique feature that lets you flip the panels up and out of the way so you can inspect the roof and perform routine maintenance without taking apart the system.

high quality, long lasting materials

Light but strong all aluminum and stainless-steel construction means the SunLink system is rugged, durable, corrosion-free, and elegant. Your building is a valuable asset. SunLink helps you keep it that way.

modules are more efficient

PV modules produce less power when they get hot. The SunLink design promotes air circulation keeping modules cool and efficient.

higher energy output

Only SunLink offers 5°, 10°, 15°, and 20° tilt angles. A steeper angle receives more sunlight which translates to more annual energy production, lower electric bills and, in many cases, no electric bills.

The following submittal allows for the installation of QTY(1000) 175W MonoCrystalline SolarWorld Modules on the roof of the New Jersey Public Health, Environmental and Agricultural Laboratory at a tilt angle of 5 degrees using SunLink mounting hardware. It is important to confirm that the roof structure of the NJPHEAL is capable of supporting a distributed load of up to 7lbs./sf additional to the code compliant snow load. It is in this safety margin of structural performance that a self ballasted mounting system which tilts the modules at 5 degrees can be mounted without penetrations to the roof. Based on a 100 MPH 3 second gust, and exposure class B the preliminary dead loads of the non-penetrating PV systems for the 88’ high upper roof, the 64’ high lower roof and 31’ high Pavillion roof are 6.7 PSF, 6.1 PSF, and 5.0 PSF respectively.

3.2. Array Mounting Structure – Sunlink (Continued)

SunLink® is compatible with all PV modules and needs no roof penetrations. The building owner will love the roof friendly features and you’ll appreciate how product testing and support can smooth the permitting process.

easy to permit

The SunLink system has been successfully permitted on 100’s of projects in virtually every wind, snow and seismic zone across the country. Our system has also undergone the most rigorous wind tunnel testing and computer modeling in the industry. Combine this breadth of experience and this depth of data with our expert engineering and sales support and we have what it takes to help you get your project through the process.

worry free

Non-penetrating mounting means leak-free liability. Rust resistant materials leave no unsightly stains on the roof. And our 15-year warranty assures that SunLink stands behind what it sells.

appealing aesthetics

Clean lines, crisp design and advanced aerodynamics makes the SunLink system one of the most visually appealing PV products available anywhere. We took an under appreciated but vital component and gave it heft, grace and an elegance that complements the architecture of any flat roof building.

brilliantly engineered

This highly engineered system is among the most roof-friendly offerings in the market requiring minimal or no roof penetrations to secure it to the building. Additionally, the unique design virtually eliminates ponding and lightweight but strong aluminum construction is rust-free and corrosion resistant.

wind tunnel tested

Subjecting the SunLink mounting system to the most extensive and sophisticated wind tunnel testing available has placed SunLink among the world’s foremost authorities on the wind’s effects on PV arrays. Component and system modeling, finite element analysis, mechanical load testing, structural frame analysis, electrical bond testing, wire management modeling and materials environmental testing round out the company’s rigorous product development process.

proven in the field

Nearly 200+ SunLink systems have been sold in 17 states and Canada totaling more than 30 Megawatts. From Hawaii to New York, in virtually every wind, weather and seismic zone, SunLink systems are meeting the needs of building owners, building departments and the building trades.

every roof unique

Because no roof is alike and every installation is custom, our engineers work in consultation with roofers, roof manufacturers, building owners, facility managers, architects, engineers, permitting authorities and independent consultants to design the optimized mounting architecture specifically for that site.

experienced expertise

Our sales team excels in helping clients define their needs; our designers produce layouts that optimize module placement at the site and our engineers deliver the data, calculations and the analysis to meet even the most stringent of building codes. Whether you need some questions answered or complete specifications, SunLink can deliver what you require.