Is your business a good fit for solar?

Commercial solar tends to work best when a site uses a meaningful amount of electricity during daylight hours. Offices, warehouses, factories, retail premises, cold storage, schools and health facilities can all fit that pattern, but the shape of the load matters more than the industry label.

If your building is almost empty through the day and most electricity use starts after sunset, solar may still make sense. The economics are simply different. You may need to look harder at export value, load shifting or storage rather than assuming every kilowatt-hour generated will replace a grid purchase.

The roof also needs to cooperate. Useful area, orientation, shading, skylights, access paths, roof condition and structural capacity can all affect the final array. A large roof is helpful, but it is not a reason on its own to install the largest possible system.

Start with interval data, not the quarterly total

A bill tells you how much electricity the business bought. Interval data shows when it bought it. That difference is critical.

Victoria's smart-meter systems can provide consumption data by day and hour. For a commercial solar assessment, at least 12 months of interval data is a much better starting point than annual consumption alone because it shows weekday patterns, weekends, seasonal peaks and after-hours load.

It is also worth separating energy charges from demand charges. Solar can reduce daytime grid consumption, but the effect on a demand charge depends on when the site's highest demand occurs and how the tariff is structured.

THE USEFUL DATA PACK

Collect 12 months of electricity bills, interval data, the current retail contract or tariff, the site NMI, operating hours, roof plans if available, and details of any planned new electrical loads such as EV charging, heat pumps, refrigeration or new machinery.

How should a commercial solar system be sized?

There is no universal commercial size. A 30 kW system can be sensible for one business while a 300 kW system is conservative for another.

The first question is how much daytime load the site can absorb. The next questions are how much roof area is usable, what the network will approve, whether export has value, and whether electricity demand is likely to grow.

For context, the Victorian Government uses roughly 450 to 600 square metres of clear roof area as a guide for a 100 kW system. Actual layouts vary with panel dimensions, access requirements, roof geometry and obstacles.

A system can also be intentionally larger than the site's current daytime load if the business has a sound reason, such as planned electrification, fleet charging or a battery. That decision should appear clearly in the modelling rather than being hidden inside an optimistic payback figure.

Read the commercial system sizing guide ↗

Commercial solar incentives changed in 2026

Victoria now has a dedicated Victorian Energy Upgrades activity for eligible commercial and industrial solar systems from 30 kW to 200 kW. The system must meet the program rules and be installed through an accredited provider.

Federal support also changed on 1 October 2026. Eligible solar systems above 100 kW and up to 1 MW can now receive Small-scale Technology Certificates under the expanded Small-scale Renewable Energy Scheme. The Clean Energy Regulator applies a fixed five-year deeming period to eligible mid-scale systems through 2030.

Those two programs are separate. A project may be able to use more than one incentive, but the installer or certificate provider should confirm the eligibility and certificate treatment for the actual site before the contract is signed.

See the current commercial solar rebates and discounts guide ↗

What should be in a commercial solar proposal?

A useful proposal should make its assumptions visible. You should be able to see the proposed panel and inverter capacity, expected annual generation, expected on-site use, export assumptions, tariff assumptions and the treatment of incentives.

For larger projects, it should also explain the network connection pathway, any expected export constraint, roof and structural requirements, monitoring, warranties and who is responsible for approvals.

Commercial proposal checklist

  • At least 12 months of interval data used in the model.
  • Solar generation and self-consumption shown separately.
  • Import rates, export rates and demand-charge assumptions stated.
  • Proposed DC array size and inverter capacity clearly identified.
  • Network connection and export assumptions documented.
  • VEU, STC or other certificate values shown separately from the base price.
  • Structural assessment, access, monitoring and shutdown requirements explained.
  • Product, installation and workmanship warranties supplied in writing.

If two proposals show very different savings for similar hardware, compare the assumptions before comparing the headline payback period.

Commercial solar guides

Sources and further reading

Source labels identify who published each reference, not an independent endorsement. Confirm current requirements and exact product terms before purchasing.