Cat® PVT110, PVT115, PVT117, PVT120 Photo Voltaic Module {1471, 4822} Caterpillar

Photovoltaic

PVT110 (S/N: TF21-UP)

PVT115 (S/N: TF51-UP)

PVT117 (S/N: TF71-UP)

PVT120 (S/N: TF81-UP)

Introduction

Cat Photo Voltaic (PVT) modules are manufactured in state-of-the-art facilities using a highly innovative process that rapidly deposits thin films of semiconductor on glass. The modules have been designed to have a long operating life and high energy yield when installed, operated, and serviced in accordance with the instructions in this installation guide. Cat PVT modules are electrically and mechanically compatible with one another, provided appropriate system design practices are employed. Use only Cat PVT modules within the same interconnected string.

Before You Begin

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

This document provides guidelines and information on Cat PVT modules for system designers, installers, and maintenance personnel. Read this installation guide thoroughly before beginning any work related to the installation, operation, or maintenance of the Cat PVT module. Only qualified personnel should install, operate, or maintain a PVT module or system.

Failure to follow installation and handling instructions may result in injury.

Failure to maintain proper operating condition requirements for the modules will void the applicable warranties.

This installation guide pertains to modules installed within North America only. If a module is being installed outside of North America, contact your local Cat dealer or visit www.cat.com for the installation guide appropriate for other geographic areas.

Keep this installation guide for future reference.

Guidelines related to system construction are beyond the scope of this document and are not covered in this document.

Key Product Features

• High energy yields in real-world conditions.

• Size and weight that enables efficient handling and installation.

• Easy, quick-connect wiring for fast interconnection.

• Compatible with advanced 1500 VDC plant architectures.

• Internationally recognized product certifications.

• 25-year limited performance warranties.

Safety

The PVT modules may produce voltages up to 110 VDC and currents up to 3.0 Amps when exposed to sunlight. A single module could create a lethal shock hazard during hours of daylight, including periods of low light levels. The danger increases as modules are connected together in series and/or parallel.

To avoid fire and/or injury due to ground fault and associated electrical hazards:

• Do not unplug PVT module connections while under load. Do not disconnect the module connectors during daylight hours unless the module is in an open circuit condition or all modules in series and parallel are covered with an opaque material, such as a tarp or blanket.

• Repair or replace damaged wires immediately. Keep all array wiring out of reach of non-qualified personnel.

• Do not concentrate light on the module in an attempt to increase power output.

• Never allow the PVT array system voltage to exceed 1500 VDC under any condition.

• Replace broken modules immediately.

• Repair any ground faults immediately.

• Do not work on modules or systems when the modules or wiring are wet.

Reverse currents higher than the rated values for a Cat module (reverse current overload), may result in module failure, including module breakage. Extreme and continuous reverse current overload conditions may cause a fire or create electrical shock hazards. To avoid reverse current overload:

• Maintain equivalent voltage in parallel strings by installing an equal number of modules per string within the same source circuit. Failure to install modules with balanced voltage in parallel strings can result in voltage imbalance.

• Comply with all practices as stated in this document and repair ground faults.

Wear electrically rated Personal Protective Equipment (PPE) when working on interconnected modules or system components. PVTs are not compatible with other manufacturers modules within the same interconnected string.

• To avoid risk of fire, only interconnect PVT modules within the same interconnected string.

Regulatory Compliance

The installer and/or system integrator are responsible for ensuring compliance with all local electrical codes which maybe applicable to the installation and use of Cat PVT modules.

• Before beginning the PVT system design and installation, contact appropriate local authorities to determine local code, permit, and inspection requirements.

• For systems installed in Canada, installation shall be in accordance with "CSA C22.1, Safety Standard for Electrical Installations", "Canadian Electrical Code, Part 1."Cat PVT modules are listed by a nationally recognized test laboratory to "UL 1703", the standard for Flat-Plate Photovoltaic modules and panels.

To maintain the modules application as a UL Listed product:

• Use only components that have been recognized or listed by Underwriters Laboratories (UL) for their intended purpose.

• Ensure the PVT array open-circuit voltage does not exceed 1000 VDC.

• Install modules with mounting systems that have been evaluated for UL Listed application as specified in the "Mounting Guidelines"section of this document.

• Protect modules from reverse currents more than the maximum series fuse rating of 4.0 A as specified in the "Reverse Current Overload"section of this document.

PVT meets the requirements of Safety Class II for 1000 VDC systems and Safety Class 0 for 1500 VDC systems. PVTs are tested and certified per "IEC 61730" Application Class A up to a maximum system voltage of 1000 V and Application Class B up to a maximum system voltage of 1500 V, both with maximum over current protection ratings of 4 A.

PVTs are tested and certified per "IEC 61215-1-2:2016", "IEC 61215-1-4: 2016", and "IEC 61215-1-3:2016"for a maximum system voltage of 1500 VDC.

Electrical Specifications

Table 1

Model Numbers and Ratings At STC(1)
Nominal Values	Description	PVT 110	PVT 115	PVT 117	PVT 120
Nominal Power (± 5%)	PMPP (W)	110.0	115.0	117.5	120
Voltage at PMax	VMPP (V)	67.8	69.3	70.1	70.8
Current at PMax	IMPP (A)	1.62	1.66	1.68	1.70
Open Circuit Voltage	VOC (V)	86.4	87.6	88.1	88.7
Short Circuit Current	ISC (A)	1.82	1.83	1.83	1.84
Maximum System Voltage	VSYS (V)	1500 VDC(2)
Limiting Reverse Current	IR (A)	4.0	4.0	4.0	4.0
Maximum Series Fuse	ICF (A)	4.0
Operating Temperature	−40° C (−40.0° F) to 85° C (185.0° F)

(1)	As received and stabilized ratings at Standard Test Condition (STC) (1000W/M2, AM 1.5 25° C (77° F)) ±10%.
(2)	1000 VDC for UL listed

Note: As received and stabilized ratings at Standard Test Condition (1000W/m², AM 1.5 25° C (77° F) cell temperature) ±10%.

Note: The ratings listed above are UL Listed with a tolerance of ±10%.

Note: Electrical specifications are subject to change. See the module label for more electrical ratings.

System Derating Factors

Under normal operation, a photovoltaic module may experience conditions that produce more current and/or more voltage than reported at standard test conditions. Therefore, when determining component ratings, the values listed for open circuit voltage should be multiplied by a calculated factor based on the low temperature open circuit voltage temperature coefficient. Refer to the "PVT Module System Operating Voltages"section of this document for additional information on the calculation of this voltage multiplication factor. Values listed for current should be multiplied by 1.25. Refer to Section 690-8 of the "National Electrical Code" for an extra multiplying factor of 125% (80% derating) which may be applicable in computation of maximum circuit current for proper conductor sizing. Adjustments of those factors might be needed to respect site-specific climate conditions.

Mounting Guidelines

The information contained in this section is intended to provide designers of PVT module mounting and support systems with both minimum requirements and recommendations for the development of mounting solutions which will satisfy the Cat technical and mechanical requirements to provide a safe and approved solution for the installation of all PVT modules.

The information contained in this document is not exhaustive and does not consider all technical design requirements. Rather, it provides the minimum required mounting provisions to ensure that PVT modules perform in a safe, compliant, and reliable manner.

Note: It is the responsibility of vendors, customers, installers, design professionals, and engineers to follow a due diligence process to ensure that the structure meets applicable structural and electrical code requirements of the jurisdiction where the product will be sold or installed. Cat is not responsible for bonding failure, breakage, damage, wear, or module performance issues deemed to be caused by design or installation practices.

Module Physical Specifications and Dimensions

Module physical dimensions provided in Table 2 below are for reference only. Refer to product drawing 488-1763 Module As. Photovoltaic 110, 513-1319 Module As. Photovoltaic 115, 527-6075 Module As. Photovoltaic 117, and 527-8800 Photovoltaic Module As. 120 for the exact dimensions of the module.

Table 2

Dimensions and Tolerances of Module
Length	1200 mm (-0.79 mm/+ 5 mm) (47.2 inch (-0.031 inch/+0.197 inch))
Width	600 mm (-0.79 mm/+ 5 mm) (23.6 inch (-0.03 inch/+0.20 inch))
Thickness	6.8 ± 0.2 mm (0.27 ± .01 inch)
Weight	12 kg (26.4 lb)
Area	0.72 m2 (7.75 ft2)

Module Mounting Locations

The module shall be secured to the support structure with clips (or equivalent) at four (4) symmetrical points. The location of the clips shall be along the 1200 mm (47.2 inch) length of the module, and the center point of the clip shall be located between 250 mm (9.8 inch) and 300 mm (11.8 inch) from the module corner. Illustration 1 and Illustration 2 depict the modules retaining clip locations.

Illustration 1	g06254882
Recommended Location of Retaining Clips (front side)

Illustration 2	g06254899
Recommended Location of Retaining Clips (back side)

Mounting Structure and Clip Shading Considerations

When module cells are sharply shaded over their full length by structural components, the modules cells may experience localized areas of reverse bias (negative voltage/positive current). This may result in damage. Refer to the "Module Field Shading Guidelines" section of this document for further information.

While countless ways exist to shade a module, a few typical field scenarios that pertain directly to clips and structural components can be divided into no risk and high risk.

• No Risk:Shading of active area under typical module mounting clips mounted on long edges of modules poses no risk to reliability or performance.

• High Risk:A structural component or mounting method on the short edges of modules that fully shades the entire length of a cell (either partial or complete width of cell) can create a high risk of undesirable shading.

Module Orientation Specifications

Module mounting in landscape orientation is required for any tilted applications where row-to-row shading is present. Portrait orientation is prohibited where row-to-row shading is present. Portrait orientation is allowed where no row-to-row shading is present (a flat rooftop or parallel to tilted rooftop). Tilted portrait mounting requires a slide protection.

Retaining Clip and Mounting System Required Minimum Specifications

Illustration 3	g06254951
Example of a Module 1 mm Apart from the Vertical Edge of the Clip

Cat requires that a module retaining clip and mounting system must meet the following minimum specifications:

• The retaining clip and mounting system (retaining system) shall not compromise the integrity of the module under the applied load as defined in "IEC 61215-1-2:2016", "IEC 61215-1-3:2016", and "IEC 61215-1-4 2016"

• The retaining system shall not deflect more than 0.01 mm/mm (0.0004 inch/inch).

• The clip and support rail retaining system shall be designed with one another and must have a gap on the vertical edge to the module of 1 mm (0.04 inch) to allow for thermal expansion in the width and length of the module glass. Refer to Illustration 3.

• A minimum gap of 10 mm (0.4 inch) between two modules is required to prevent the contact between the modules.

• The retaining clip shall have a "hard stop" that limits the top and bottom surfaces of the insulator material compression by a maximum of 10% at maximum torque of fastening hardware.

• The retaining clip shall provide a gap of less than 6.8 ± 0.2 mm (0.267 ± 0.008 inch) to allow for the thickness of the module and when installed, the insulator material shall compress in a range of 5% to 10% at maximum hardware torque.

Clip and Mounting System Recommended Minimum Specifications

Caterpillar recommends that a module retaining clip and mounting system should meet the following minimum specifications:

• A module surface contact length of 70 mm (2.3 inch) ( 80 mm (3.2 inch) preferred).

• Front side module surface contact width between 13 mm (0.5 inch) and 15 mm (0.6 inch)

• Minimum back side module surface contact width of 15 mm (0.6 inch).

The retaining clips may be designed to support the module from either both the front side and back side surfaces, or only the front side surface. If the clip is designed to support and retain the module only at the modules front side surface, the design and profile of the support rails to which the clips are mounted must be considered to satisfy the minimum back side surface contact width.

Support Rail Specifications

Module support rails (or equivalent) shall be designed to provide a uniform plane for installation for the modules and module rail deflection shall not exceed the maximum deflection specified above. The support rails shall be designed to support the modules, either across the 600 mm (23.6 inch) width of the module or along the entire span of the 1200 mm (47.2 inch) length of the module. See Illustration 4. Details A, B, and C.

Illustration 4	g06254965
Support Rails and Modules Orientations

Module retaining clips can be either a one-part or two-part design (separate top half and bottom half). See Details A and B in Illustration 5

Illustration 5	g06254974
One-part and Two-part Clips

If a two-part clip design is used, the width of the underlying module rail is not relevant, but the module rail shall not exceed the maximum deflection specified.

If a one-part clip design is used, Table 3 defines the support rail width and contact surface area width for the two typical module support rail orientations. The module rail deflection shall not exceed the maximum deflection specified. See Illustration 6 details A, B, C, and D for examples of module rails and the required module surface contact.

Table 3

Support Rail Width and Contact Surface Width Requirements
Module Retaining Clip Type	Refer to Illustration 6	Rail Span Direction	Minimum Rail Width	Minimum Rail Contact Surface Width
One-Part Design	Detail A	Along Module Width	40 mm (1.6 inch)	30 mm (1.2 inch)
One-Part Design	Detail B	Along Module Width	Same As Clip and Rubber Insert 15 mm (0.6 inch)	Same As Clip and Rubber Insert 15 mm (0.6 inch)

Illustration 6	g06255211

Module support rails, clips, and rubber shall be fabricated from corrosion and UV resistant materials (ex. pre-galvanized steel, hot dipped galvanized steel, aluminum, stainless steel, powder-coated steel, etc.) that will maintain structural integrity over the lifespan of the modules (minimum 25 years).

Fasteners

It is the responsibility of vendors, customers, installers, design professionals, and engineers to follow a due diligence process to ensure fasteners used prevent galvanic corrosion, environmental corrosion, and provide electrical bonding between the clip and underlying structure as defined by local codes and jurisdictions. Caterpillar does not make recommendation or test fasteners for these requirements. Fasteners used in the mounting system testing provided by vendors, customers, installers, design professionals, and engineers are expected to meet all these and necessary mechanical strength requirements.

Insulators and Protective Materials

Laminate modules must be electrically insulated and protected from direct contact with metallic surfaces of retaining clips, support rails, or other structural support components. Insulation and protective materials tested and approved for use by Caterpillar for Cat PVT module types are typically Thermoplastic Elastomer (TPE) materials such as a cross-linked EPDM+Polypropylene blend or equivalent and must have the minimum thickness specified in Table 4. Minimal material thickness is 3 mm (0.1 inch) for the top and bottom sections, and 2 mm (0.08 inch) for the vertical section, both with volume resistivity > 1.0 x 10¹⁴ Ohms • cm per "ASTM D257".

Illustration 7	g06255321

Table 4

Clip Insulator Minimum Dimensions
Top Section: 3 mm (0.1 inch) minimum.(1) (includes "teeth"or "ridges")
Bottom Section: 3 mm (0.1 inch) minimum(1) (includes "teeth"or"ridges") for two-part clips and 5 mm (0.2 inch) minimum(1) (includes "teeth"or ("ridges") for one-part clips.
Vertical Section: 2 mm (0.08 inch) minimum..

(1)	Minimum: Manufacturer material low tolerance thickness when compressed 10%

Insulator materials shall be UV resistant and designed to maintain integrity over the lifespan of the modules (minimum 25 years). Typical rubber durometers range from 45 to 75 on the Shore A scale.

Moisture Drainage and Air Circulation

Retaining clips shall be designed and installed to facilitate drainage at the module interface, and should be designed to prevent the trapping of moisture inside the clip or at the edge of the laminate module. In addition, the module structure should be designed to maximize air flow under the module to control the module operating temperature.

Clip and Mounting System Approval

Caterpillar reserves the right to test samples of proposed retaining clip and support rail designs prior to approval for use with Cat modules. Caterpillar may, at their sole discretion, test the supplied samples per the procedures defined in "IEC 61646 10.16 (Mechanical Load Test)" to 2400 MPa (348,100 psi)), "UL 1703 Section 41 (Mechanical Loading Test)" to 2.1 kPa (0.3 psi)), and/or other tests deemed appropriate by Caterpillar. If multiple retaining clip and module rail profile combinations are available, all combinations shall be disclosed to Caterpillar for review and testing to worst case scenario. Samples submitted to Caterpillar for testing shall be supplied with the respective clips, fasteners, and module rails as per submitted design drawings.

It is the responsibility of vendors, customers, installers, design professionals, and engineers to perform static load test as defined in "IEC 61646, 10.16" and verify compliance prior to submitting samples to Caterpillar for approval.

Any mounting solution that deviates from the dimensional guidance for the clip, rails, or mounting configuration as specified above shall be considered to be in compliance with this document if it has been proven with high confidence (sample size >5 per configuration) to pass the test procedures defined in "EC 61646 10.16 (Mechanical Load Test)" to 2.4 kPa (348.1 psi)), IEC 61730 MST 32 (Module Breakage Test), UL 1703 Section 41 (Mechanical Loading Test to 2.1 kPa (304.6 psi)), "IEC 62782" Dynamic Mechanical Loading and/or other tests deemed appropriate by Caterpillar. A detailed test report that documents the test setup, method, and results shall be provided to Caterpillar for review and approval.

Reverse Current Overload

Purpose

The purpose of this section is:

• To describe the system conditions that can cause reverse current overload (RCOL) and the behavior of PVT modules in this condition.

• To provide information on mitigating the potential causes of RCOL.

• To provide information on protection of PVT modules in the event of reverse current flow.

Definitions

1. Reverse Current Overload:

   A condition where an electrical current more than the rated maximum over current protection value flows through a PVT module in the direction opposite to the direction of current flow in normal operation. Refer to Table 5for these values.

   Show/hide table

   Table 5

   Rated Maximum Over Current Protection
   Module Type	Rated Maximum Over Current Protection
   PVT	4.0A

2. Positive Voltage Bias:

   A differential electrical potential between two terminals of a device that is in the same polarity as the bias during normal operation.

3. Open Circuit Voltage:

   The difference of electrical potential between positive and negative terminal of the PVT module or string of modules when no external load is connected.

4. Array:

   An electrically connected collection of PVT modules.

5. Grounded Conductor:

   The wires or electrical bus in a PVT system electrically connected to an earth ground with an electrical potential of zero with respect to an earth ground.

6. PVT Source Circuit:

   Electrical circuits between modules and from modules to the common connection points of the DC system.

7. Ground Fault:

   Accidental electrical grounding of a PVT system component.

8. Ground Fault Detector Interrupter:

   A safety device for a PVT array which, if the array becomes shorted to ground, disconnects the PVT system from ground.

Background Information

When a PVT array is exposed to light, PVT modules within the array normally operate at a voltage between zero and the modules rated Voltage Open Circuit (V_OC). When the modules are generating electrical power, the conventional flow of current through the module moves from the negative to the positive terminal. If an abnormal condition develops within the array and positive voltage bias more than the rated V_OC is applied to a PVT module (or series of modules), and if sufficient current is present, current will flow though the module in a reverse direction (positive to negative). Under this scenario, instead of generating electrical power, a PVT module behaves as a load and attempts to dissipate electrical power mainly in the form of heat. When this power dissipation exceeds the level that can be tolerated by the module (as defined by module safety tests), the module experiences a condition known as a Reverse Current Overload (RCOL).

There may be a risk of RCOL if a single PVT module is exposed to positive voltage biases more than ~1.4 times its labeled V_OC. An RCOL condition can cause the PVT module to dissipate electrical power which can result in module overheating and eventually failure. A string of PVT modules may also be affected in a similar manner if the string is positive biased more than 1.4 times the sum of the V_OC ratings of the PVT modules in the affected string. For example, a series of four PVT modules may experience RCOL if a positive voltage bias is generated by several parallel strings of six modules.

Operating a PVT module in a sustained RCOL condition is likely to result in module failure. Several factors influence the likelihood of module failure. These are the magnitude of the reverse current, the duration of the RCOL event, ambient conditions, system design, etc.

International PVT module standards ("IEC 61730", UL 1703, and "EN 50380") include required testing which establishes the reverse current tolerance characteristic for PVT modules under the defined test conditions of these standards. According to "UL 1703", PVT modules must be labeled with the ‘maximum series fuse rating’ required to protect the module from failure as defined in the testing protocol for this standard. According to "IEC 61730", information on the modules maximum over current protection rating must be included in the modules documentation. According to "EN 50380", information on the modules limiting reverse current rating must be included in the modules data sheet. These values are listed in Table 6.

Table 6

Rated Maximum Over Current Protection by Standard
Module Type	UL 1703	IEC 61730	EN 50380
PVT	4.0A	4.0A	4.0A

Effects of Reverse Current Overload on PVT Modules

When reverse current flows into a module, instead of producing electricity the module acts as load and will attempt to dissipate the energy flowing into the module. Reverse current passing through the module exceeds its maximum reverse current rating as shown in Table 5, RCOL occurs. When RCOL occurs, the module may experience high surface temperatures, and could crack, smoke, or ignite itself or surrounding materials, depending on the length and severity of the RCOL condition.

Refer to the PVT Module installation guide for further information on the proper operating conditions for PVT modules and for specific warning and caution information related to the installation and use of PVT modules.

Conditions Which Can Cause Reverse Current Overload in PVT Modules

The conditions which are necessary to trigger RCOL in PVT modules do not occur in the typical operating modes of a properly installed PVT system. The specific conditions which could potentially result in RCOL occurrence are:

Voltage Imbalance

1. For RCOL to occur in a string, the effective open circuit voltage of the string needs to be less than 70% of the open circuit voltage of the rest of the strings in the array.

2. A string that has effective open circuit voltage that is less than 70% of the open circuit voltage of the rest of the strings in the array can be created by the formation of an effective short string that contains the electrical equivalent of 70% of the modules in the rest of the strings in the array (assuming all modules have nominally equal voltage). Some examples of effective short strings include 4 or fewer modules for arrays designed with 6 modules per string, 7 modules or fewer for arrays designed with 10 modules per string, and 10 modules or fewer for arrays designed with 15 modules per string.

There are multiple ways in which effective short strings can be created:

1. Ground fault of module lead wire or module in a string shorting the modules between the location of the ground fault and the ground, creating an effective short string.

   • Grounded PVT System: A single ground fault inside a string.

   • Ungrounded PVT System: A single ground fault inside a string AND another ground fault that is simultaneously present at any point in the array.

2. Installation error which results in the existence of one or more effective short strings in the array.

3. The existence of multiple shorted modules (module fault) inside an otherwise properly installed single string.

Grid Fault and Inverter Failure

In addition, RCOL could be created in an array where all the strings are substantially of the same voltage through a voltage/current surge from the inverter due to grid fault and failure of the inverter to protect the array from this event, biasing the whole array to an extreme voltage which is larger than the inherent V_OC of the array.

Note: Shading of some of the PVT modules in a string can result in small reverse currents, but these reverse currents will not exceed the PVT modules limiting reverse current specifications. Module shading does not lead to an RCOL condition.

Mitigation Approaches

PVT systems should be designed to prevent the conditions that trigger module RCOL. The system designer should ensure that modules are not subjected to reverse currents more than the module rating.

The use of Ground Fault Detector Interrupter (GFDI) devices or other advanced fault monitoring techniques can significantly reduce the likelihood of sustained ground faults. By ensuring the ground current cannot exceed the maximum over current rating of the module, the likelihood of RCOL will be reduced dramatically. If a GFDI limits the ground current to remain below maximum events will be low and will not increase with additional strings connected to a single fuse.over current rating of the module, the likelihood and severity of RCOL

PVT modules must be installed to ensure an equal number of modules per string in the same PVT source circuit. Failure to do so may result in voltage imbalance, which in turn could trigger reverse current flow within the PVT array.

Properly selected and installed string fuses or blocking diodes can increase protection against RCOL. For example, a system which incorporates a single fuse per string of modules, where the fuse is no larger than the modules maximum series fuse rating, typically provides adequate module protection against RCOL.

The system designer is responsible for complying with all applicable laws and codes related to the system designers installation. Application of PVT modules in different geographical locations requires that the system designer understand the local regulatory requirements which may apply to a particular installation site. It is recommended that the system designer consult with the local electrical code officials well before the installation.

Installation

Mounting

Physically damaged modules may cause ground faults and associated electrical hazards. To avoid these conditions:

• Handle modules with care during installation, as heavy impact on the front, back, or edges could result in damage to the module. Do not walk or stand on modules.

• Do not stack or carry multiple modules on top of one another after removal from factory packaging to minimize the risk of breakage.

• Do not lift or pull on modules using lead wires or strain relief wire loops to minimize the risk of wire damage.

• Do not install the modules during high wind or wet conditions to reduce the likelihood of injury.

• Wear safety glasses (ANSI Z87.1-2003) and cut-resistant gloves when working on non-interconnected modules or systems.

• Wear electrically rated PPE when working on interconnected modules or system components.

Mounting of the PVT module to a suitable structure can be done by attaching the module directly to the structure using retaining clips.

Any module without a frame (laminate) shall not be considered to comply with the requirements of "UL 1703" unless the module is mounted with hardware that has been tested and evaluated with the module under this standard or by a field inspection certifying that the installed module complies with the requirements of "UL 1703". The PVT module is a frameless laminate and is considered to be in compliance with "UL 1703" only when the module is mounted using approved hardware in the manner specified by the mounting instructions in the "Mounting Guidelines" section of this document.

Additional mounting systems may be approved for use. Retaining clip designs must meet the technical requirements specified in the "Mounting Guidelines" section of this document and must be approved for use by Caterpillar prior to installation. The mounting system design must provide adequate support for the module to prevent damage from occurring when the module is subjected to wind loads of 130 km/h (80.8 mph), with a safety factor of 3 for gusty conditions. The location of the clips shall be along the 1200 mm (47.2 inch) length of the module and the center point of the clip shall be located between 250 mm (9.8 inch) and 300 mm (11.8 inch) from the module edge. Rubber insulator material, or equivalent must be used between the module and both the clip and mounting structure to provide adequate protection of the module. No direct contact of rigid structures is permitted against the surface or edges of the module.

All mounting structures must provide a flat plane for the modules to be mounted on, and must not cause any twist or stress to be placed on the module.

Modules should not be installed in a way that restricts air circulation to the underside of the module. Modules generate heat and require adequate airflow for cooling. Installation locations and module support structure should be selected to ensure modules and connectors (open or mated) are never submersed in standing water. Cat modules are tested and certified for applications involving pressures from snow/ice/wind up to 2400 Pa (50 lb/ft2) when mounted properly. Drifting snow could result in a non-uniform loading of the modules which exceeds the tested pressure. If the load is expected to exceed 2400 Pa (50 lb/ft²), clear snow from the modules and ensure that ice/thaw/freeze cycles under snow drifts do not result in excessive stresses on the module.

Heavy construction and trenching should be completed prior to module installation to minimize debris and dust.

Ensure any soil binding agents or salts used for on-site dust control do not spray, splash, or drift onto the surface of the modules.

The UL approved design load of PVT is 1436 Pa (30 lb/ft²).

Maximum allowable pressure on modules may not exceed 2400 Pa (50 lb/ft²) without additional module support that must be tested and approved by Caterpillar.

For rooftop mounting, modules must be mounted over a fire-resistant roof covering rated for the application. The recommended minimum standoff height is 82.55 mm (3.25 inch). Modules used in UL Listed rooftop applications must be installed with approved mounting systems. If alternate mounting means are employed, this may affect the listing fire class ratings and additional UL fire testing may be required. The fire rating of this module is valid only when mounted in the manner specified in the mechanical mounting instructions.

Tool As

Illustration 8	g06368730
Tool As

528-5367 Tool As is a jig used to provide an alignment aid for the installation of Photovoltaic Modules (PV).

Location, Angle, and Tilt

To maximize performance, modules should be located in an area that receives direct sunlight from mid-morning to midafternoon (typically 9:00 a.m. to 3:00 p.m.). Installation must avoid locating the modules where shadows may be caused by buildings, trees, and so on.

PVT performance modeling software should be used to determine the optimum orientation and tilt angle for each location.

For tilted free-field applications where there is row to row shading, modules shall be installed in landscape orientation.

Refer to the "Module Partial Shading Response"section of this document for additional information.

Module Shading Considerations

To minimize the risk of module shading damage, follow directions found in the "Module Field Shading Guidelines" section of this document. Instances of shading that will lead to a voided warranty include the high risk listed items below.

High Risk (Prohibited) Shading

1. Resting or adhering slender objects (tools, brooms, clothing, wires, tape) on sunny side of operating modules, or within inches above operating modules, especially when shadow oriented parallel to cells.

2. Fixed objects within 1.5 m (5.0 ft) to 2.1 m (7 ft) above operating modules that cast a shadow over the long dimension of the cell should be avoided. Close objects like posts, ropes, signs, fences, or equipment can begin to ease risk of partial shading of full cells when nearer than 1.5 m (5.0 ft) to 2.1 m (7 ft) from the sunny-side of operating module.

3. Working continuously with outstretched arms or tools over operating modules.

4. A support frame or mounting method on the short edge of modules that fully shades the entire length of a cell (either partially or completely).

5. Cleaning apparatuses, including cleaning robots and other mechanisms that traverse the module repeatedly while the system is operating (unless evaluated and approved by Caterpillar).

Electrical Interconnection

Cat PVT modules are pre-configured with industry standard connectors that are “touch proof” with all live parts protected against accidental contact and protected against polarity reversal. The cables and connectors are UV and weather resistant from −40° C (−40.0° F) to 90° C (194.0° F), and rated for 1500 VDC and 22.5 A (minimum, before derating for ambient temperature). Damaged wires, connectors, or junction boxes may cause ground faults, and associated electrical hazards, including electrical shock. To avoid these conditions:

• Protect unmated connectors from dust and moisture by using sealing caps (not provided, available from connector manufacturer).

• Limit module connectors to 10 or fewer plug cycles.

• Do not pull lead wires tight at any time. After installation, the connected wire must not be under stress or tension.

• Do not use junction box assembly or lead wire strain relief loops to secure excess wire or to bear weight more than a modules own wire and mated connector pair.

• Do not tightly secure connector bodies and cables at both ends to any mounting structure to allow for thermal expansion and contraction.

• Secure wire or connected components so that no loose wires or components are hanging within 0.46 m (1.509 ft) of the ground in free field applications, and so that wire/components are hanging clear of roof coverings or pooled water in rooftop applications.

• Ensure that connectors are fully mated.

• Ensure wire securement methods, such as use of cable ties, do not damage wire insulation. The minimum module lead wire bend radius is 5 times wire diameter. Observe minimum bend radius specifications on all other PVT system wiring.

• Inspect and maintain wire management requirements over the life of the plant. Other manufacturers modules have different electrical operating characteristics and should not be interconnected within the same inverter or MPPT to prevent power output loss and voltage imbalance conditions that may create the risk of reverse current overload.

Module-to-module and module-to-harness interconnection is advised between same manufacturer and type of connectors. The Cat module warranty is not affected by the interconnection of different supplier connectors, however, Caterpillar cannot guarantee that different connector types will be mate able in every connection instance. Components used to interconnect the modules must be compatible with the connectors, and provide proper system operation and fault protection as required by any applicable codes. Field wiring must be rated for 90° C (194° F), and be of a type approved for use in accordance with the NEC.

Inverter Compatibility

PVTs are designed for utility grid connected, commercial, and industrial, off-grid energy access, and fuel displacement applications. Cat PVT modules are compatible with a range of string, central, and inverters without transformer. All inverters must be approved for module compatibility by Caterpillar prior to installation to preserve module warranty. Contact the application support center for a list of approved compatible inverters. When connecting modules or module strings in series ensure that inverter ratings are appropriate.

When selecting an inverter, system bias conditions and grounding should also be considered. Cat PVT modules can be used in negative-grounded or ungrounded installations. Use in bi-polar systems should be reviewed in detail by Caterpillar prior to approval. Do not use PVT modules in positive-grounded systems.

When connecting PVT modules in a series string, ensure that the system design voltage and inverter design specifications are not exceeded. The "PVT Module System Operating Voltages" section of this document should be referenced when determining the site-specific maximum open-circuit system voltage (V_OC) seen by the inverter. For 1000 VDC applications, this is typically ensured by limiting series strings to 10 modules or less. For 1500 VDC applications, this is typically ensured by limiting series strings to 15 modules or less.

The Maximum Power Point (MPP) voltage of a module array must be considered for compatibility with the specified MPP window of the inverter. Similar to the maximum open-circuit voltage, the MPP voltage of the array depends on ambient conditions, and the system should be designed to ensure that the MPP voltage of the array remains within the MPP window for expected operating conditions.

Grounding Method

Per the requirements of "UL 1703", a module with exposed conductive parts is considered to be in compliance with "UL 1703" only when it is electrically grounded in accordance with the instructions presented and the requirements of the National Electrical Code.

PVT modules have no exposed conductive surfaces and do not require equipment grounding as long as a clip length of 100 mm (3.9 inch) for a standard 4-clip mounting is not exceeded. In the U.S., the mounting structure must be grounded per the requirements of the NEC, sections 250 and 690.

PVT modules can be used in grounded, ungrounded, floating, and bi-polar system architectures, provided all appropriate design requirements are met and approved by Caterpillar.

Over Current Protection

PVTs have a maximum series fuse rating of 4.0A as defined by "UL 1703" test methods.

PVTs have a maximum over current protection rating of 4.0 A as defined by "IEC 61730" test methods.

PVT systems should be designed to comply with and provide module over current protection consistent with local codes as appropriate for the intended application class of the system.

Refer to the "Reverse Current Overload"section of this document for additional information on module over current protection.

Mechanical Specifications and Drawings

Table 7

Specifications	Cat PVT
Length	1200 mm (47.2 inch)
Width	600 mm (23.6 inch)
Thickness	6.8 mm (0.27 inch)
Area (Total Aperture)	0.72 m2 (7.75 ft2)
Weight	12 kg (26.5 lb)
Fire Rating	Class B (Class A Spread of Flame)
Operating Temperature	−40° C (−40.0° F) to 85° C (185° F)

Illustration 9	g06254762
Mechanical Drawing for PVT Modules

Proper Operating Conditions

The proper operating condition requirements listed below must be maintained.

Note: Failure to maintain proper operating condition requirements for the modules will void the applicable warranties.

Requirements:

• Short circuit operation is permitted only during short duration system safety testing or in fail-safe system states.

• All electronic components that are interconnected to modules must have an operating voltage window that matches the maximum power point of the array, and be able to operate the array at the maximum power point at alltimes.

• All electronic components that are interconnected to modules must be rated for the maximum operating voltage of the array.

• Modules must have adequate ventilation and airflow to prevent operating temperatures above 85° C (185.0° F).

• Modules must not be partially shaded by obstructions at times of high irradiance (typically between 9:00 a.m. and 3:00 p.m.). Module row-to-row shading in landscape orientation is acceptable, module row-to-row shading in portrait orientation is prohibited.

• Do not remove strain relief cable ties .

• If module cleaning is undertaken, modules must be cleaned only when in open circuit – either disconnected from load, or during times when inverter is turned off and otherwise in accordance with latest version of OMM , M0082623., "PVT120 Photovoltaic Modules".

• PVT modules include anti-reflective coated glass. Use of prohibited cleaning methods can reduce the energy enhancing effects of the anti-reflective coated glass and void warranty. Refer to the latest version of OMM , M0082623, "PVT120 Photovoltaic Modules" for allowable cleaning methods compatible with PVT modules.

Service

• Periodically, annually at a minimum, inspect modules for any signs of damage or broken glass. Visual irregularities which do not impact power are normal.

• Broken modules should be replaced immediately. If broken modules are found, place material into a closed container for return to Cat recycling program, or dispose of module in accordance with local requirements.

• Check that all electrical connections are tight and corrosion free.

• Large amounts of dust and dirt on the surface of the module can reduce the power produced. Natural rainfall will typically remove most dust. Should auxiliary cleaning be required, refer to the latest version of OMM , M0082623, "PVT120 Photovoltaic Modules" for allowable cleaning methods compatible with PVT modules.

The most common causes of lower than expected PVT system power output are:

• Inverter failure.

• Improper or faulty field wiring or connections.

• Blown fuses or tripped circuit breakers.

• Excessive amounts of dirt and dust on the modules.

• Shading of modules by trees, poles, or buildings.

• Improperly calibrated or malfunctioning monitoring equipment

PVT Module System Operating Voltages

The National Electrical Code (NEC) defines that the maximum system voltage for a Photovoltaic (PV) System is to be determined using the open circuit voltage (V_OC) of PV modules. Due to the performance characteristics of PVT thin film modules, increased open circuit voltage may occur at low operating temperatures. This document provides a summary of the method used to calculate a low temperature correction factor to be applied to open circuit voltage for PVT thin film photovoltaic modules.

Discussion

Article 690.7 of the NEC directs the maximum system voltage to be calculated as:

• The sum of the rated open-circuit voltage of the series-connected photovoltaic modules corrected for the lowest expected ambient temperature.

• Where other than crystalline or multicrystalline silicon photovoltaic modules are used, the system voltage adjustment shall be made in accordance with the manufacturers instructions.

In the 2011 version of the NEC, Article 690.7 added a clause to define the calculation method to be used:

When open-circuit voltage temperature coefficients are supplied in the instructions for listed PVT modules, they shall be used to calculate the maximum photovoltaic system voltage as required . NFPA 70: National Electrical Code – 2011 Edition, Article 690.7 (A)

This document summarizes Caterpillar manufacturer instructions to be used when calculating the maximum system voltage in compliance with the NEC (editions 2011 and earlier).

Effects of Temperature on V_OC

The temperature dependence of V_OC at low cell temperatures is weaker than that observed at the higher (typical) operating ranges traditionally used to determine temperature coefficients. This is apparent in the non-linearity of normalized V_OC vs. module temperature. For this reason, applying a temperature coefficient derived from a linear regression to data over typical operating temperatures 25-50° C (77.0 -120.0° F) will overestimate V_OC at low module temperatures. Deriving a temperature coefficient specifically across the coldest temperature range of −45° C (−49.0° F) to 25° C (77.0° F) using a linear regression is a more accurate approximation of cold temperature behavior is obtained.

V_OC Correction Factor

To determine the final factor to be used as the multiplying factor for V_OC per the method outlined in the 2011 edition of the NEC, the measured V_OC data in Table 8was fit with a least-squares fourth order polynomial function. This function was then evaluated to obtain a factor for each of the temperature intervals below. The lowest temperature in each 5° interval was used in the calculation as a conservative assumption. To determine the corrected V_OC according to the 2011 NEC, apply the V_OC correction factor from Table 8 to the modules V_OC at standard test conditions (STC), as given in the PVT data sheets.

Table 8

Ambient Temperature °C	Ambient Temperature °F	VOC Correction Factor
24 to 20	75 to 68	1.017
19 to 15	66 to 59	1.026
14 to 10	57 to 50	1.038
9 to 5	48 to 41	1.046
4 to 0	39 to 32	1.057
-1 to -5	30 to 23	1.068
-6 to -10	21 to 14	1.076
-11 to -15	12 to 5	1.083
-16 to -20	3 to -4	1.090
-21 to -25	-6 to -13	1.097
-26 to -30	-15 to -22	1.106
-31 to –35	-24 to -31	1.118
-36 to -40	-33 to -40	1.121
-41 to -45	-42 to -49	1.128

Module Field Shading Guidelines

PVT modules are tested and certified by an accredited third-party laboratory to be compliant to IEC 61646 Edition 2.0 Thin Film Terrestrial Photovoltaic (PVT) modules – Design qualification and type approval. This is the international standard governing thin film module performance testing. Section 10.9 of "IEC 61646" details the "Hot Spot Endurance Test". The purpose of the test is to verify that modules can withstand certain reverse bias events, caused by localized shading, which may occur in certain field deployment conditions. The concern of device damage due to shading is unrelated to reverse current, but is driven by localized areas of reverse bias (negative voltage/positive current). This happens when modules are shaded in only very specific patterns. However, when the shading geometry is suitable for damage to occur, it can happen in short durations (seconds to minutes) and under a wide range of irradiance (as low as 150 W/m²). Reverse bias is generated by 1 or more series-connected cells being shaded while the rest of the cells are fully illuminated. However, no damage is seen when greater than 45% of series-connected cells are shaded. All cells in series connected modules are included.

The illuminated cells push forward current through the shaded cells. As a result, the shaded cells operate in reverse bias, because the cells are not generating voltage from sunlight exposure. An example of prohibited shading is presented in Illustration 10.

Illustration 10	g06255857

There are countless ways to shade a module. A few typical field scenarios are discussed to clarify the impact of common behaviors relative to a PVT system using Cat modules.

No Risk Shading

1. "Row-to-Row" shading, where modules are oriented in landscape and exposed to uniform shading pattern as a result of low sun angles, poses no risk to long-term reliability or performance.

2. Shading while modules are in Open Circuit (OC) conditions poses no risk to long-term reliability or performance. OC is defined as the condition when modules, strings, or arrays are electrically open and not actively driving current flow. OC conditions are common during storage, unboxed transport, installation, or when inverters (or loads) are off or disconnected. Any shading during these OC conditions, regardless of how many cells are shaded or at what contrast or intensity, will not create reverse bias events because no current is flowing through the module. With no reverse bias, there is no risk.

3. Shading of active area under typical module mounting clips mounted on long edges of modules poses no risk to reliability or performance.

4. A support frame or mounting method on the short edges of modules that fully shades the entire length of a cell (either partially or completely) can create a high risk of undesirable shading.

5. Diffuse shading (no crisp edge to the shadow) cast as a result of faraway objects like overhead power lines,Caterpillar).

Low Risk Shading

1. Repeatedly walking or standing closely in front of operating modules between rows during highly illuminated times can create highly irregular shading difficult to predict and test. Best practice is to stay as close to the back side of the rack as one walks down a row of operating modules. These irregular actions present a low risk of high contrast shading, and should be systematically avoided.

2. Repeated parking or driving of vehicles or equipment closely in front of operating modules can potentially create undesirable high contrast partial shading of complete cells, and should be systematically avoided.

High Risk (Prohibited) Shading

1. Resting or adhering slender objects (tools, brooms, clothing, wires, tape) on the sunny side of operating modules, or within inches above operating modules, especially when shadow oriented parallel to cells, can create high risk of undesirable shading.

2. Fixed objects within ~ 1.5 m- (5 ft)- 2.1 m (7 ft) ft above operating modules that cast a shadow over the long dimension of the cell should be avoided. Close objects like posts, ropes, signs, fences, or equipment can begin to increase risk of partial shading of full cells when nearer than ~5-7 ft from the sunny-side of operating module.

3. Working continuously with outstretched arms or tools over operating modules can create high risk of undesirable shading.

4. A support frame or mounting method on the short edge of modules that fully shades the entire length of a cell (either partially or completely) can create a high risk of undesirable shading.

5. Cleaning apparatuses, including cleaning robots and other mechanisms that traverse the module repeatedly while the system is operating unless evaluated and approved by Caterpillar.

Module Partial Shading Response

The information contained in this document provides supplemental information about the response of PVT due to partial module surface area shading and its dependence on the orientation of the shading. The data is intended to support the proper design of systems using these PVT modules and the development of more accurate models for energy prediction. The data is representative of all power bins of PVT modules, although some variation among the modules is normal and to be expected.

Shading Parallel to Cells

Illustration 13 shows how the IV curve of a single PVT module changes as entire cells are shaded. In this case, shading occurred along the 600 mm (23.6 inch) dimension of the module, completely obscuring some cells. The number of entirely shaded cells increases with the total shading percentage. The shaded cells act to limit the current and power produced by the module. The maximum power P_MAX and maximum power voltage V_MP are reduced upon shading of the first 5-10% of the module surface area, but do not vary much as the amount of shading increases from 10% to 30%. In this range, the P_MAX value is approximately one half of the value for an unshaded module. Beyond the 10-30% range, additional reduction in P_MAX and V_MP occurs with increased shading.

This effect is also evident in Illustration 14, which shows P(V) curves corresponding to the I(V) curves shown in Illustration 13. Response of the relative module power output to shading percentage is shown in Illustration 17, which indicates that the module ceases producing power when more than half of the cells are entirely shaded.

Illustration 11	g06256169
Shaded Along 600 mm Dimension

Shading Perpendicular to Cells

The response of the module to shading along the 1200 mm (47.2 inch) dimension is shown in Illustration 15. In this case, all cells of the module remain partially illuminated and the unshaded portions of the cells function normally. Thus the resulting power loss from shading scales proportionately with percentage of shaded module surface area. In this case, the maximum power voltage V_MP is only slightly affected by the degree of shading, shifting by about 3V (or about 7%) from the fully illuminated case to the 75% shaded case. The weak dependence of V_MP on 1200 mm (47.2 inch) shaded area percentage is also shown by the approximate vertical alignment of the maximum power points in Illustration 16.

The maximum power current IMP varies directly with unshaded (active) cell area. Since this dependence is linear, and since the V_MP response is only weakly dependent upon shaded area, the resulting dependence of module power is nearly linear with shaded area percentage. This behavior is clearly shown in Illustration 17. A linear fit to the relative power versus shading percentage in the 1200 mm (47.2 inch) dimension shows good agreement with the data.

Illustration 12	g06256192
Shaded Along 1200 mm Dimension

Conclusions

PVT modules respond differently to partial shading depending on shading orientation. If the shading occurs along the 600 mm (23.6 inch) dimension of the module, output power of the module initially drops to approximately half of the unshaded value for shadings of 10-30% of module surface area. Beyond 30% shading, the output power drops further, eventually reaching zero when more than 50% of the module is shaded. V_MP can vary appreciably over the entire range, but remains nearly constant when 10-30% of the modules surface area is shaded.

If the module is shaded along the 1200 mm (47.2 inch) dimension, output power of the module varies linearly with the percentage of unshaded module surface area, and V_MP remains unchanged with less than 50% of the module surface area shaded.

Based on these behaviors, module power loss due to shading will be minimized when shading can be restricted to occur along the 1200 mm (47.2 inch) dimension of the module (ensuring no cells are entirely shaded). In a typical free-field application where modules might be affected only by row-to-row shading, mounting modules in a landscape orientation would result in minimization of power loss due to shading.

Illustration 13	g06256287
I(V) Curves for a PVT Module with Some Cells Entirely Shaded. Shading Occurred Along the 600 mm Dimension

Illustration 14	g06256290
P(V) Curves for a PVT Module with Some Cells Entirely Shaded. Shading Occurred Along the 600 mm Dimension.

Illustration 15	g06256298
I(V) Curves for a PVT Module with all Cells Partially Shaded Along 1200 mm Dimension

Illustration 16	g06256317
P(V) Curves for a PVT Module with all Cells Partially Shaded Along 1200 mm Dimension

Illustration 17	g06256326
Relative Module PMAX as Function of Shaded Module Portion, for Both Shading Orientations

Box Handling and Storage

This section provides information about the recommended handling of the standard box used to store and ship PVT modules

Each Cat packing box is filled with 50 modules, along with internal support material. For planning purposes, a fully loaded box weighs up to a maximum of 665 kg (1466 lb). Packaging and wrapping variation may result in slightly lower actual weights. The box includes an integral pallet for easy forklift transport. To maintain intended strength, all boxes should remain dry and packed full with modules and support material. The modules and internal support material are integral to the strength of the packaging. When full, intact, and dry, the boxes can be vertically stacked indoors, up to 4 boxes high for extended periods of time. If any of the modules or support materials are removed from the box or the box is damaged or becomes wet, the boxes should not be stacked in any fashion.

When handling boxes using forklifts or other mechanical aids, ensure that the box is supported uniformly, and that the forks are fully extended under the pallet. Do not scrape, pierce, or bend the walls or cover of the boxes; the support capacity of the boxes will be weakened and the modules could be damaged. Do not stack any boxes that have been physically damaged in any way.

Indoor box storage is recommended. If the boxes are stored outdoors, the boxes should be covered and protected from moisture. Stacking of boxes outdoors is not permitted. Once a box has become wet, drying will not restore the boxes original strength. Never stack boxes that have been wet. Do not use boxes that have been wet transporting modules.

Note: Failure to follow these recommended handling guidelines may result in damage to modules that will not be covered under the PVT module warranty.

Illustration 18	g06256380
50-module Box and Pallet Dimensions

Note: All dimensions in centimeters [inches]. Dimensions should be used for general guidance only. Caterpillar may update or modify box without notice.

Partially Full Boxes

There may be instances, for example at a project site, when boxes have to be repacked and there may not be enough modules to fill a 50-pack box. Under these circumstances, the following guidelines should be followed:

• Do not use boxes that have been wet for transporting modules.

• Modules should be packed starting in the center of the 50-pack box and moving outward symmetrically towards the front and back to ensure that weight balance is maintained. See Illustration 19

• Two persons should be used to load modules when one person cannot walk into the box for safe lifting.

• No boxes should be stacked on top of partially filled boxes.

• Modules should be packed face-to-face in pairs within each slot, along with reused paper separator to minimize breakage risk due to transport/vibration. The clip shown in Illustration 20 is only used to keep the paper separator in place until another module can be placed in the slot.

Illustration 19	g06256392

Illustration 20	g06256394