Solar Panels and BASIX: When Do They Help?

Solar panels can help with BASIX energy compliance in NSW because they reduce the net energy impact of a residential project. In BASIX, solar photovoltaic systems are treated as an alternative energy source. When the project has suitable roof space, good solar access and clear documentation, solar PV can support the energy section of the BASIX Certificate.

However, solar panels should not be treated as a simple last minute fix for every BASIX issue. The system needs to be realistic for the site, located on the same land as the development and coordinated with roof layout, shading, orientation, hot water choices and other energy commitments. If the BASIX Certificate relies on solar PV, the commitment should match the plans and be carried through into the project documentation.

How solar panels fit into BASIX

BASIX covers water, energy use and thermal performance for NSW residential development. Solar panels sit within the energy side of the assessment because they generate electricity on site. NSW Planning describes an alternative energy system as a system that generates electricity on the land subject to the application, using an energy source other than the electricity supply grid, including photovoltaic systems and wind generators. NSW Planning Portal

For solar PV, NSW Planning explains that BASIX assesses photovoltaic systems as an alternative energy source based on the total rated output of all solar panels, measured in kilowatts. The size of the photovoltaic system is generally limited by cost and the availability of suitable, unshaded roof space. NSW Planning Portal

Does BASIX require solar panels?

BASIX does not require solar panels for every project. Some projects may meet their energy target through other design and system choices, such as efficient hot water, heating, cooling, ventilation, lighting and building performance. Other projects may need solar PV to help reach the required energy outcome, especially where energy demand is higher or where certain system selections need to be offset.

For example, NSW Planning states that electric instantaneous or storage hot water systems are recognised in new dwellings and alterations and additions if offset by solar PV. It also notes that if a new PV system is included, the BASIX Tool will calculate the minimum size of the system required. NSW Planning Portal

When solar panels help most

Solar panels tend to help most when the project needs stronger energy performance and the roof can support a practical PV system. They may be especially helpful where the project includes all-electric systems, electric hot water, high energy demand, limited alternative energy options or a design strategy that relies on on-site generation to support the BASIX energy score.

Solar PV may be useful when:

• The project needs additional support to meet the BASIX energy target.
• The roof has suitable, unshaded space for solar panels.
• The design is all-electric or moving toward electrification.
• The project uses electric hot water that needs to be offset by solar PV.
• The client wants lower future operational energy use.
• The project is being designed with Whole of Home performance in mind.

When solar panels may not solve the problem

Solar panels do not solve every BASIX issue. They help with energy outcomes, but they do not directly fix water performance or thermal comfort problems. If the project is failing because of glazing, insulation, orientation, shading or heating and cooling loads, solar PV may not be the right first solution.

For example, a home with excessive west-facing glazing may need better shading, glazing performance or insulation before the thermal comfort outcome can be resolved. A project with a water target issue may need rainwater, fixture or landscaping adjustments instead. Solar is powerful, but only for the right part of the BASIX assessment.

Roof space and shading matter

Solar PV only helps when the proposed system can realistically fit on the roof or another suitable part of the site. Roof pitch, orientation, roof form, skylights, vents, plant equipment, overshadowing, neighbouring buildings and trees can all affect how much suitable space is available.

Because NSW Planning notes that PV system size is generally limited by suitable, unshaded roof space, the solar commitment should be checked against the roof plan before the BASIX Certificate is finalised. If the roof cannot realistically fit the nominated system, the certificate may create a commitment that is difficult to deliver later.

Solar PV and hot water choices

Solar PV can interact with hot water choices in BASIX. Some hot water systems may perform better in the energy section than others, and electric instantaneous or storage systems may require solar PV offset under BASIX settings. This means the hot water system and solar PV strategy should be reviewed together rather than separately.

For an all-electric home, solar PV may be part of a broader energy strategy alongside a heat pump hot water system, efficient heating and cooling, good building fabric and practical roof design. For other projects, solar may be added mainly to support the BASIX score. In either case, the commitment should be clear and buildable.

New solar PV versus existing solar PV

There is an important difference between a new PV system proposed as part of the project and an existing PV system already installed on the property. NSW Planning states that if a new PV system is included, the BASIX Tool will calculate the minimum size of the system required. If an existing PV system is included, an Alternative Assessment is needed and details of the existing PV system must be provided.

This can be relevant for alterations and additions, where a home may already have solar panels installed. The assessor needs to know whether the project is proposing new PV, relying on existing PV or changing the existing system as part of the works.

Can changing solar panels affect a BASIX Certificate?

Yes. Changing the solar PV system can affect a BASIX Certificate if the system is part of the energy commitments. This includes changing the system size, removing panels, shifting panels to a shaded roof area or discovering that the nominated system cannot physically fit on the available roof space.

If solar PV changes after the BASIX Certificate has been issued, the certificate should be checked before the project relies on it for approval, construction certification or installation. Some changes may be acceptable, while others may require an amended assessment.

What information does the assessor need?

To assess solar PV properly, the assessor needs enough information to understand the system and where it will be located. If the BASIX Tool calculates a minimum required system size, the project team still needs to make sure that size is practical for the roof or site.

Useful information includes:

• Whether the PV system is new or existing.
• Total rated output in kilowatts, if known.
• Roof plan showing available panel location.
• Roof orientation and pitch, if available.
• Any overshadowing from trees, neighbouring buildings or roof elements.
• Whether solar PV is being used to offset electric hot water.
• Whether batteries are proposed as part of the wider energy strategy.
• Any solar installer or product information already available.

How Certified Energy can help

Certified Energy prepares BASIX Certificates for NSW residential projects and can review how solar PV affects the BASIX energy outcome. Our team can help identify whether solar panels are likely to support the project, whether the commitment needs to be shown on the plans and whether the energy strategy is coordinated with hot water, heating, cooling and Whole of Home performance.

This is especially useful for new homes, alterations and additions, secondary dwellings, dual occupancies, townhouses and multi dwelling projects where solar commitments, roof design and BASIX energy targets need to be coordinated before lodgement.

Related resources

• Complete Guide to BASIX Certificates in NSW
• BASIX Certificate Service
• BASIX Hot Water Systems: What Should You Choose?
• BASIX and Whole of Home: What Is Changing?
• Whole of Home Energy Assessments

Frequently asked questions

Do solar panels help with BASIX compliance?

Solar panels can help with BASIX energy compliance because BASIX assesses photovoltaic systems as an alternative energy source. The benefit depends on the system size, available roof space, shading, orientation, project type and other energy commitments.

Does BASIX require solar panels?

BASIX does not require solar panels for every project. However, solar PV may be useful or necessary in some projects to help meet the energy target, especially where other energy choices create a higher energy demand.

How does BASIX assess solar PV?

BASIX assesses solar photovoltaic systems as an alternative energy source based on the total rated output of all solar panels, measured in kilowatts. The system must be located on the same land as the proposed development.

Can changing solar panels affect a BASIX Certificate?

Yes. Changing the size, location or availability of solar panels can affect the BASIX energy outcome. If a BASIX Certificate relies on a solar PV commitment, the system should match the certificate and the plans should be checked before approval or construction.