Changes to PV arrays installation standard

A new version of AS/NZS 5033 standard for installation of photovoltaic (PV) arrays came into effect from July 2012 and changes are mandatory from 16 October 2012. The EL-042 Standards Committee oversees the development of renewable energy standards and includes electrical safety bodies, fire brigade representatives, training organisations and other relevant industry groups.

The Clean Energy Council (CEC) sits on the committee and has prepared a technical information sheet detailing the revisions and implications for installers. Below are some key points from the technical sheet that will help you understand the changes.

General

• Modules in the same string shall be installed in the same orientation. (Clause 2.1.5)
• Domestic voltage rating of installation limited to 600 Volts DC. (Clause 3.1)
• Greater than 600 Volts DC requires restricted access to all installed equipment. (Clause 3.1)
• Change of safety class, from Class II to Class I, for PV module insulation system rating, (Clause 1.4.1.1) earthing is required of all exposed metal module frames and mounting rails. (AS/NZS 3000 1.4.27)
• All equipment and wiring shall be selected and installed in accordance with the provisions of AS/NZS 3000 and the requirements of this Standard. (Clause 4.1)

Wiring

All PV wiring and components must be fit for purpose and installed to minimise exposure to detrimental environmental effects (clause 4.1) and are protected from abrasion, tension, compression and cutting forces. They need to be routed, supported and protected in accordance with AS/NZS 3000. (Clause 4.3.6.3)

• PV array cabling is to double insulate (Clause 3.2) and be flexible (multi strand) to allow for movement. (Clause 4.3.6.2)
• Needs to meet PV1-F specification and be tinned copper to reduce degradation of the cable over time. (Clause 4.3.6.2) TPS cable is not permitted.
• PV cabling must be identified with a permanent, indelible marking in English or coloured “SOLAR” labels attached at intervals of not less than 2 metres. When the PV cable is enclosed in conduit or other wiring enclosure a coloured “SOLAR” label must be attached at each end of the wiring enclosure and at each change of direction. (Clause 5.3.1)
• The solar array to inverter solar DC cables within buildings shall be in heavy duty conduit. (Clause 4.3.6.3.2)
• All outdoor equipment must be suitable for the environment and be at least IP 54 and UV resistant. (Clause 4.3.3.1)
• If exposed to the environment, cabling shall be UV resistant or protected from UV by installation in UV resistant conduit marked with “T”. (Clauses 4.3.6.2 and 4.3.6.3)
• When installed on roofs or floors must be mechanically protected (in enclosures or conduit) and not obstruct natural water drain paths or promote accumulation of debris. (Clause 4.3.6.3)
• Are protected from abrasion, tension, compression and cutting forces. (Clause 4.3.6.3)
• Plastic cable ties are not to be used as a primary means of support. (Clause 4.3.6.3)
• Ensure wiring in enclosures and cable entries maintain the IP rating and are sealed to manufacturers specifications and double insulation between conductors is maintained and installed in such a way as to minimise strain on the connectors. (Clause 4.4.4.4)
• Connectors are mated with connectors of the same type from the same manufacturer. (Clause 4.3.7)
• String fuses in PV arrays are rated for DC (Clause 4.3.1) and are rated to interrupt fault currents from the PV arrays. (Clause 4.3.4)
• Fuse holders shall have a current rating equal or greater than the corresponding fuse and provide protection suitable for the location. (Clause 4.3.9.1)

Disconnection devices

• An isolating/disconnection device shall be installed at the array if the PCE is more than 3 metres from the array. (Clause 4.4.1.4)
• An isolating/disconnection device shall be installed adjacent to the PCE. (Clause 4.4.1.4)
• Disconnection devices will be not be polarity sensitive and must operate in all active conductors. (Clause 4.3.5.2)
• If circuit breakers are used they are not to be polarity sensitive. They must also be rated to interrupt the full load when operated and have a voltage rating greater than VOC. (Clauses 4.3.1 & 4.3.4)
• Must be certified to AS/NZ 60898 or IEC 60947. (Clause 4.3.5.2)
• All PV array switch-disconnectors are readily available (Clause 4.4.1.4) and are to be marked with an identification name or number according to the PV array wiring diagram. They shall have a clear indication of isolation position “off” and “on” eg, O and I. (Clause 5.5.1)
• When the PCE has an internal means to isolate the solar array this switch-disconnector shall be mechanically interlocked so that it will isolate the array if repair or replacement of a module is to be carried out within the PCE. (Clause 4.4.1.2)
• Where multiple disconnection devices are installed they are either ganged so that they all operate simultaneously, or grouped in a common location with a warning sign indicating the need to operate all switch-disconnectors to isolate the equipment. (Clause 4.4.1.3).

Earthing

PV module and mounting frame earth connections are to be a purpose-made fitting providing earthing or bonding connections or purpose-made penetrating washers or equivalent between the PV modules and mounting frame for the connection of dissimilar metals purpose-made fittings are installed to manufacturer’s instructions. (Clause 4.4.2.2)

• Cable lugs, earthing termination and bonding cables are to be fixed by stainless steel bolts, washers and pentrating washers to aluminium frames. (Clause 4.4.2.2)
• Earthing or bonding connections must be arranged so the removal of a single module earth connection will not affect the continuity of the earthing or bonding connections to any other module. (Clauses 4.4.2.2 & 4.4.2.3)
• Self-tapping screws cannot be used for earth connections to the PV array framework. (Clause 4.4.2.2)

PV array functional earthing

Connection to earth is at a single point, connected to the main earthing terminal of the electrical installation. This connection point is between the PV array disconnection device and the PCE and as close as possible to or located inside the PCE (Clause 4.4.3.1). The PV system functional earthing conductor has the same rating as the earth fault interrupter EFI (Clause 4.4.3.2).

LV PV arrays with functional earthing

On an earth fault the EFI interrupts the earth fault, shuts the PV system down and provides a fault indication and an external fault alarm. (Clause 3.4.2)

The standard also includes requirements for system documentation and commissioning. A copy of the standard can be purchased from SAI Global at http://infostore.saiglobal.com/store/ or by calling 131 242.