DG66 Photovoltaic Solar Power Generator

This design guide details the design requirements for new solar PV systems. It also details the requirements for upgrades to existing PV systems.

For new schools and new building/s (on an existing school site) a photovoltaic (PV) solar power grid-connect rooftop system shall be provided to offset power consumption costs at the school.

66.3.1 System Size

For a new school provide the system size as tabled below:

For a new building at an existing school site the PV system must be sized to offset at least the power consumption of the new building/s using predicted energy consumption data for the site and a current energy bill.

Any proposed PV system on a new or existing school must show a simple payback period of 7 years or less.

66.3.2 Personnel

The designer of any PV system shall be fully accredited by the Clean Energy Council (CEC) of Australia for Grid-Connected PV Systems (Design).

The Contractor engaged to install the PV system must be fully accredited by the Clean Energy Council of Australia for Grid-connect PV Systems (Installation). The CEC accredited installer(s) shall at a minimum supervise the installation throughout the duration of the project.

66.3.3 PV array arrangement

PV array location

Selection of PV array location(s) shall consider the following:

• CEC Design Guidelines Cl. 7. Site-specific information
• Replacement schedule of existing roofs
• Heritage listing of building –solar array shall not be located on heritage listed buildings
• Roof cladding type – solar arrays shall not be located on tile roofs .

PV array arrangement

PV modules shall be arranged so that they are grouped together where possible and are symmetrically or geometrically arranged.

The arrangement of the PV array should be designed to available space:

• PV array must be arranged such that shading of PV modules by nearby buildings, trees, obstacles or the PV modules themselves between the hours of 9:00am and 3:00pm during all months is avoided or minimised. Note: SG933 section 1.5 specifies the requirements for quantification of shading losses.
• All modules shall be installed with a minimum incline of 10° to ensure self-cleaning by rainfall.
• PV arrays shall be designed so that debris does not catch underneath panels, especially if there are trees in the vicinity. This may be achieved by
  
  • Positioning the mounting system so that it runs vertically in line with the corrugations of the roof and ensuring a minimum of 50mm clearance between roof cladding and module frame.
  • Installation of tray or mesh guard around the perimeter of the array where debris build-up is likely. This shall be installed in a manner that does not hinder module performance or system maintenance.

To minimise mismatch losses, PV arrays shall be arranged such that:

• All strings connected in parallel to the same MPPT input comprise the same number of panels and have the same module brand and model.
• All modules in the string have the same tilt and the same orientation unless prior approval has been obtained.

Maintenance access

Arrays should be arranged as follows so that adequate access is provided for maintenance of the array:

• 500mm clearance around the perimeter of the PV arrays
• For flush mounted arrays, provide at least 700mm gap at every fourth row to create maintenance access way;
• Ensure that access to individual PV modules does not require the removal of more than one other PV module.

PV array in shared spaces

PV systems may be installed at a location adjacent to open play space used by students. This arrangement shall be considered as ‘PV array in shared space’.

Where PV arrays or other PV system components are installed in shared spaces, a permanent fencing structure may be required to separate PV array and PV system components from unauthorised access. 

Fencing shall be located minimum 3 metres away from array, and such that shade cast onto the array is minimised. There should be no shading from the fence between 10am and 2pm in winter months.

See SG242 Landscape Structure - Fences and Barriers for fencing requirements. Fencing for the purpose of preventing access in shared spaces shall meet requirements for SG242 Cl 3.4 Chain Link Fabric Security Fencing and Gates or SG242 Cl.3.9 section ‘Weldmesh Fencing, security’.

Where PV arrays are installed in shared spaces, all cables shall be concealed in covered cable tray, ducting and/or conduit.  

The final design for PV arrays in shared spaces must be reviewed by SINSW Sustainability and Advisory Services SINSW, Department of Education.

66.3.4 PV system inverter station arrangement

The area surrounding the inverter and all associated protective devices such as PV array DC isolator, inverter AC isolators, and wiring shall be considered as the inverter station.

The inverter station shall be located and specified such that:

• Requirements as per CEC Design Guidelines Cl.8. Inverter Installation are met.
• The ventilation ,clearance and other requirements specified by the inverter manufacturer are met. This includes DC and AC protective switchgear unless explicitly approved by manufacturers in writing.

Locate cupboards so that access is available only directly from general circulation areas. It is not acceptable to walk through classrooms etc. to gain access to inverter stations, or to locate inverter stations in store rooms.

Where the EDB cupboard is unsuitable to house the inverter and associated equipment due to its size, ventilation or other issues, installation of the inverter station/s should be in one of the following locations:

• Plant room
• Purpose built enclosures/shelters

Where the inverter station location may be exposed to direct sunlight or rain, additional shading/protection must be provided.

Equipment at the inverter station should be arranged as follows:

• Arrange DC cables and isolator switches to the left side of each inverter.
• Arrange AC cables and isolator switches to the right side of each inverter.
• Arrange all switching devices and inverters no lower than 0.5 m and no more than 2.0m above the ground, floor or platform.
• Allow 0.6m access clearance in front of all switching devices and inverters .
• Where the PV system contains multiple PV array and/or inverters, provide additional description indicating location of system components and electrical distribution boards to which the inverter systems are connect.

66.3.5 PV system electrical design

The design of the PV system shall meet requirements as set out by the Clean Energy Council Grid Connected Solar PV systems – Design guidelines for accredited installers.

Array and Inverter Matching

Inverters shall be sized and selected adhering to requirements of CEC Design Guidelines Cl.9 Inverter Selection. In addition:

• Safety margin of 5% shall be applied to inverter maximum input voltage
• The inverter and PV array should be sized such that the PV array nominal capacity rating is greater than 95% of the inverter's nominal AC power rating.

The oversizing restrictions of the CEC design guidelines shall be met for systems intended to create Small-scale Technology Certificates.

Cable selection

DC and AC cables shall be selected to meet requirements outlined by CEC design guide and AS4777.1. Additional DNSP requirements may apply.

The distance between the inverter and the most remote PV module shall be used to calculate DC voltage drop.

Where there are multiple inverters, the distance between the inverter furthest from the point of common coupling shall be used to calculate AC voltage rise.

The cable between the inverter and the AC circuit breaker shall have a higher current carrying capacity than the AC circuit breaker rating and the maximum rated AC current output of the inverter.

AC isolators and circuit breakers

AC circuit breaker ratings shall be above inverter maximum rated AC current output rating to avoid unnecessary tripping of circuit breaker.

Where multiple inverters are installed at the inverter station, an AC isolator shall be provided for each inverter. Additionally, a single AC isolation switch shall be provided for isolation of all inverters connected to the same electrical distribution cupboard.

Design Drawings

The designer of the PV system must provide electrical schematics of the system, including electrical ratings of all isolators and switches etc. This may be presented as a wiring diagram or a single line diagram.

The designer of the PV system must also provide plan view drawings of the array layout and inverter station layout.

All drawing(s) shall identify the building and room on/in which PV system components are located, in accordance with the AMS room coding.

66.3.6 Distribution network service provider approval

The system provider must apply for and obtain the approval for connection of the proposed system from the relevant electricity distribution network service provider (DNSP ) prior to installation of the PV system.

The system provider shall meet all requirements set out by NSW Service and Installation rules and DNSP connection requirements.

System provider shall submit all paperwork and be responsible for liaison with the DNSP until the DNSP has offered a connection agreement and the agreement has been accepted by the school. A copy of all paperwork submitted to the DNSP and a formal copy of the approval shall be included in the PV system documentation.

Where an existing electricity meter requires upgrading or reconfiguration to facilitate bi-directional metering, the PV system installer must facilitate this upgrade with the sites electricity retailer.

Refer to DG61.04 / ELECTRICAL SERVICES / ELECTRICITY CONTRACT & METERING for additional information on electricity contract & metering.

66.3.7 Planning Approval under the EP&A Act and Compliance with SINSW Heritage Interim Guidelines for the Installation of Solar Panels

Under the SEPP Infrastructure 2007 (the Infrastructure SEPP) roof mounted solar can be installed at any NSW public school as exempt development if it meets certain conditions. Installations that comply with EFSG DG66 and SG933 will satisfy the majority of these conditions, but in addition, in order to satisfy the exempt development criteria the roof mounted installation:

• must not involve no more than minimal impact on the heritage significance of a heritage item* or  conservation area.
• must not be installed facing a primary road if the school is on land that contains a State or local heritage item, or is in a heritage conservation area, or on land zoned:
  • (a)  R1 General Residential,
  • (b) R2 Low Density Residential,
  • (c)  R3 Medium Density Residential,
  • (d)  R4 High Density Residential,
  • (e)  R5 Large Lot Residential,
  • (f)  RU5 Village

* According to the SINSW Heritage Interim Guidelines for the Installation of Solar Panels, roof mounted solar systems are not permitted to be installed on a heritage items as listed in the Department’s S170 Heritage and Conservation Register or pre-1950 buildings as designated in AMS as being on the Draft S170 Register.

Solar installations that do not meet the exempt development criteria set out in clauses 20 and 39(3) of the Infrastructure SEPP, and are not prohibited under the SINSW Heritage Interim Guidelines, will require the preparation of a Review of Environmental Factors (REF) in accordance with Part 5 of the Environmental Planning Assessment Act 1979 . The REF must take into consideration the factors outlined in Section 228 of the Environmental Planning and Assessment Regulation 2000. If the development is judged by the Department of Education to 'significantly affect the environment', then an environmental impact statement will need to be prepared and considered by the public authority.

It should be noted that a Statement of Heritage Impact will need to be prepared by a Heritage Professional where heritage impact needs to be assessed. For further heritage advice please contact SINSW Heritage at sinsw.heritage@det.nsw.edu.au

NOTE: For any proposed ground mounted system refer to Statutory Planning team for planning advice.

See SG933 SCHEDULE OF PHOTOVOLTAIC SOLAR POWER SYSTEM SPECIFICATIONS for full list of specifications.

The system provider shall keep copies of the PV system installation information for a minimum period of 5 years including installation and commissioning photographs.

The system provider shall explain to the system owner the operation and maintenance requirements of PV system components upon completion.

A paper copy of the PV system documentation shall be given to school office and one soft copy shall be emailed to PVsolar@det.nsw.edu.au in PDF file format with file name coded

<school code>_PVO_DDMMYY_<report description.pdf>         

For example, a file name may be titled ‘3065_PVO_010118_PublicSchoolPVinstallationhandover.pdf’.

PV system shall be designed and installed such that they are eligible for creation of STCs and/or LGCs.

NSW Department of Education retains ownership of the PV system and any benefits arising from generation of Small-scale Technology Certificates (STCs), Large-scale Generation Certificates (LGCs) and any future renewable energy schemes unless otherwise negotiated.