Standards for the PV Generator

Overview

The photovoltaic (PV) array shall consist of one or more mono- or polycrystalline photovoltaic solar module(s).

Testing of Photovoltaic (PV) Modules

• Crystalline PV modules must have been tested for qualification in compliance with IEC 61215, “Crystalline Silicon Terrestrial Photovoltaic Modules; Design Qualification and Type Approval”.
• The PV module(s) should have a rated peak power output of at least 45 Wpeak (with an allowable tolerance of -2.5 W_peak (-5%), alternatively -5 W_peak (-10%)), under Standard Test Conditions (STC) as defined in IEC 61215 and IEC 60904-3.

Comment:

To date the efficiency and reliability of “thin-film PV-modules” does not yet measure up to the standards of crystalline PV cells, and the price reduction is also still not convincing. In spite of that fact, this option might be feasible for future applications, especially for low-cost Solar Home Systems.
The World Bank has already allowed the use of thin-film PV modules in their Indonesian SHS project tender, but only one company (Canon, Japan) offered these kinds of modules in their quotation.

Optional:

If thin-film photovoltaic modules are used, they must be product-tested and certified in accordance with IEC 61646. The peak power output for thin-film modules should be the value after light soaking.

The minimum acceptable operating voltage at MPP (Maximum Power Point) of the PV module shall be no less than 16 V_dc at a cell-operating temperature of 60° Celsius.

Optional:

Each module shall comprise not less than 36 series-connected single- or polycrystalline silicon solar cells.

Comment:

In order to allow a full charge of a 12 V battery under “controlled gassing” conditions, a voltage of 14.5 to 15 V must be available at the battery terminals. Including voltage losses via cables (0.5 to 1.0 V) and blocking diodes (0.4 V/Schottky diode), the PV generator voltage should be at least 1.0 to 1.5 V above that maximum battery voltage. Under certain conditions, e.g. with the use of sealed batteries (no gassing allowed), very low system losses or permanently low ambient temperatures, this value might be lower, and even PV modules with less than 36 cells might be used. But a PVgenerator voltage of 14 - 14.5 V as recommended in the “Universal Standard” Proposal [1] will definitely be too low for SHS applications in tropical countries.

Standards: Type, Cabling, Protection Diodes

• In a PV array all modules should be of the same type and be interchangeable.
• The cabling and protection diodes must also be uniform. However, if there are sub-arrays which power separate loads or batteries, then different types of modules may be used in each sub-array if necessary.
• The module(s) shall be equipped with a sealable waterproof (international protection code IP54) terminal (junction) box. The poles inside shall be clearly marked. A strain relief for the cables must be provided.

Optional:

The junction box must have outlets that allow for attachment of flexible conduit pipes. If the module does not have a junction box which allows for a direct conduit connection, a weather-resistant junction/combiner box must be attached to the support structure.

Optional:

for system voltage greater than 50 V: The PV modules must have bypass diodes to offer protection against hot spots in case of partial shading. The PV modules shall have a frame of non-corrosive material, e.g. anodized aluminium or stainless steel. The frame shall ensure that the module is resistant to torsion during handling and extreme weather conditions.

Comment:

Only solid, framed modules are applied for SHS and RHS. At certain sites and for certain applications flexible, unframed modules may be preferred (e.g. tents of nomadic tribes). However, up to now no experience for this module type under rural conditions is available.

Labeling Modules

Each module must be clearly and permanently labelled according to DIN 40025 “Datasheets and Labels of PV Modules”, indicating: Name of Manufacturer, Model Type or Number, Serial Number, IP-Protection Code, Maximum System Voltage, Power (Watt Peak) Rating (P_max), ± Manufacturing Tolerances, Short-Circuit Current (I_SC), Open Circuit Voltage (U_OC), Maximum Power Point Voltage (U_MPP), all at Standard Test Conditions.

Warranty

The PV module manufacturer, or module supplier, shall provide a minimum 10-year warranty for the replacement of any modules which:

• show defects, in terms of the qualification test stipulations of lEC-61215
• show power degradation greater than 10% below the rated power specification

(unless damaged by abuse or extreme conditions like lightning, exceptional hail, etc., which are not covered by the qualification test conditions).

For the purpose of this warranty, the rated power specification shall be a fixed value and not a range, and to effect the warranty any tests of power degradation shall conform to the international procedures for testing and referencing PV module power output.

Clinic Name

Health, Optional: Each solar module has to have the individual clinic name sandblasted onto the bottom right-hand corner. The names are to be a minimum of 10 mm in height and are to be positioned so that the marking in no way impairs the functioning of the module or negates the guarantee issued with the module.

Download

► Download the GTZ publication "Quality Standards for Solar Home Systems and Rural Health Power Supply"

Further Information

• Solar Module Mounting
• Photovoltaic (PV)
• Solar Portal on energypedia

References

This page on standards for PV generators in Solar Home Systems is an extract of the publication quality standards for solar home systems and rural health power supply (GTZ)