A number of changes are taking place internationally to construction practices for solar, which requires current construction practices to be updated to improve electrical safety and operation. This update outlines the current position on solar standards.
Current status of Photo-Voltaic (PV) system documentation
AS/NZS 4509.1:2009 Stand-alone power systems – Part 1 Safety and installation
This standard is available and is cited by the Electricity (Safety) Regulations 2010 and AS/NZS 3000:2007 Electrical installations (known as the Australian/New Zealand Wiring Rules). It covers the installation of inverter based power systems for the supply to electrical installations that are NOT connected to an electricity distributor's network.
The energy source used to operate the inverter may be PV arrays (installed to AS/NZS 5033) and wind or mini-hydro turbines.
The limited use of a combustion engine generating sets to cover high peak loading periods is permitted.
AS/NZS 5033:2012 Installation and safety requirements for photo-voltaic (PV) arrays, including Amendments 1 and 2
This standard is available and is cited by the Electricity (Safety) Regulations 2010 and AS/NZS 3000:2007 Electrical installations (known as the Australian/New Zealand Wiring Rules). The citation in the regulations includes a variation permitting the use of heavy-duty PVC conduit as an alternative to metallic conduit for PV array output wiring contained within a building structure.
Amendment 2 delayed the introduction of inverters manufactured and approved to IEC 62109-1 until July 2015.
During the development of IEC 62109-1, a detailed study was undertaken of the requirements for better efficiency, input (D.C) to output (A.C) isolation, earth leakage detection arrangements for PV arrays, and improved reporting of fault conditions to a control point what would ensure rapid response in the event of a fault condition. The development of IEC 62109 specifications has not yet been completed and it is expected that this work will be completed in late 2014/early 2015. Inverter manufacturers have delayed work on inverters compliant with IEC 62109 until the standard has been finalised.
Amendment 3 to AS/NZS 5033 is nearing completion and will include the use of PVC conduit in lieu of metallic conduit and the use of micro-inverters. Micro-inverters are miniaturised inverters that are mounted on each panel of a PV array with the a.c. output directly connected to the electrical installation, typically through an overcurrent protection device and an isolating switch (for servicing purposes).
AS 4777.1:2005 Grid connection of energy systems via inverters – Part 1 Installation requirements
AS 4777.1 has been in use for some time and is cited in the Electricity (Safety) Regulations 2010 and AS/NZS 3000. It will continue to be cited until inverters to IEC 62109-1 are available. Inverters manufactured to AS 4777.1 are made in both Australia and New Zealand. In the short term, these inverters will continue to be installed.
AS/NZS 4777.1 Grid connection of energy systems via inverters – Part 1 Installation requirements and AS/NZS 4777.2 Grid connection of energy systems via inverters – Part 2 Inverter design
The drafting of AS/NZS 4777.1 and AS/NZS 4777.2 was completed mid-2013 and then released for public comment. Approximately 700 submissions were received, which covered nearly all sectors of a typical grid connection by an inverter and design of the inverter. Because of the numerous changes resulting from public comment, the draft standard will be released for a second public comment period prior to publication in mid/late 2014.
The standard specifies essential safety and installation requirements for inverter systems intended for the injection of electric power through an electrical installation to the electricity distribution network. It will reflect the latest international research and development.
The use of a battery to store electricity produced from a PV power system is not part of the current standard but development work is about to start on the provision of this feature. The addition of a battery completely changes the operating mode of the PV power system and additional details for screening of the LV battery connections and over current protection voltage will be added to AS/NZS 4777.1 in the near future.