Wind loading is a critical factor in ensuring the durability and safety of PV systems on rooftops or ground mounts. Under Clause 2.2.5 of AS/NZS 5033, all rooftop PV systems must meet the requirements of AS/NZS 1170.2 to withstand site-specific wind pressure loading. While most switchboard manufacturers provide guidelines to meet earlier standards, it is now the responsibility of designers and installers to ensure compliance with the 2021 update until switchboard manufacturers revise their documentation.

Updated Wind Regions

The new standard updates wind regions in Australia and New Zealand. Changes are the introduction of Region A0, central Australia with Terrain Classification 2, in place of Region A4. Region A1, previously most of southern Australia, is divided into Regions A1 and A5. Region B is split into B1 and B2, changing Northern NSW, the Gold Coast, Brisbane, and the Sunshine Coast. In addition, Tasmania is in Region A4. These alterations shift structural design criteria, with some installations found in regions B1 and B2 requiring greater supports, potentially additional rails among others.

Climate Change Multiplication Factor (Mc)

In recognition of increased extreme weather events, the 2021 standard replaces uncertainty factors (Fc and Fd) with a Climate Change Multiplication Factor (Mc) for all regions. This factor increases the required wind loading considerations in some regions. For instance, Mc is 1.05 in regions B2, C, and D, as expected higher anticipated wind loads.

Terrain Categories

Terrain categories dictate the effect of wind loads according to the surroundings. Notable changes are the elimination of Terrain Category 1.5 and the creation of Category 2.5, which pertains to open, low-vegetation sites such as industrial parks. Wind Regions C and D are now subject to linear interpolation. Thus, coastal constraints on inland facilities are not that strict.

Roof Zoning Changes

The most important modification to PV installations is the edge zone calculation on roofs, where more support mounts may be necessary. The new calculation is now based on building height-to-length (h/b) and height-to-width (h/d) ratios. Edge zones take up a larger percentage of the roof for bigger buildings, such as warehouses. Most generic structural certificates issued by manufacturers restrict installation in these zones unless modifications are done, requiring more rails or support.

Impact on PV Design and Installation

Residential buildings with reduced roof sizes do not have any significant impact because of these upgrades. However, increased edge zones and more rigorous demands for warehouse and commercial rooftops will significantly increase material and labor costs as well as lead times for installations and necessitate site-specific checks for compliance. Designers and installers should adapt to these new changes to meet compliance and maintain safe installations.

Manufacturer Responsibilities

Until mounting system manufacturers update their guidelines to reflect the 2021 standard, designers and installers must take the lead in ensuring compliance. Communication with manufacturers is essential to clarify requirements and seek updated installation guides.

Ensuring Compliance

Familiarize yourself with AS/NZS 1170.2:2021 and its implications for your region. Engage structural engineers for complex installations and obtain site-specific structural assessments to optimize mounting system design. Clear communication with manufacturers will help address uncertainties and align installation practices with the updated standards.

The updates in AS/NZS 1170.2:2021 reflect the growing need to account for extreme weather and evolving wind conditions. While compliance introduces challenges, particularly for commercial installations, understanding the changes and leveraging professional assessments can ensure safe, efficient, and code-compliant PV systems.