The short answer
Why commercial solar pays faster than home solar
Solar for a business is a better investment than solar for a home, and most guides explain it backwards. They point to a bigger system or a feed-in tariff. The real reason is your load shape. A business runs from roughly nine to five, which is almost exactly when the panels generate, so you use what you make instead of exporting it for cents. That single fact, not the size of the array, is why commercial payback typically lands at three to five years. This page explains how the numbers really work, including the 100 kilowatt certificate cliff and the demand charges that homes never pay.
Here is the core takeaway in one line: commercial solar pays faster because a business uses its power in daylight, so self-consumption is naturally high and nearly every kilowatt-hour offsets expensive grid power rather than being exported for cents. A home is empty all day and dumps its midday output to the grid for a few cents. A business is busy all day, so the same panels mostly replace power it would have bought at 25 to 40 c. That is the whole edge. It reframes every other decision: it makes sizing to your daytime load, not to export, the right move, it makes a system just under 100 kW often better value than a bigger one, and it brings demand charges into play, a saving homes never get to make.
Reframe the assumption: most business owners ask "how big a system can I fit?" The better question is "how much can I use during working hours?" A smaller array sized to your daytime load, with self-consumption near 80%, beats a larger one that exports the surplus for cents. The roof space is not the constraint. Your load shape is the prize.
Interactive explainer
What would solar return for your business?
Set your system size, your daytime self-consumption, your commercial usage rate and the installed cost per watt. The calculator models the yearly return and shows how self-consumption, not exports, drives the payback.
Know your roof? Read it from satellite
Optional. Nothing is stored. You can also just set the sliders below.
Estimated first-year saving
$/year
Illustrative only. Generation uses ~1,300 kWh per kW per year (or the Google Solar API yield if your roof is imaged). Self-consumed kWh are valued at your usage rate; the small export remainder at a token 3 c. The upfront STC discount applies only below 100 kW; at 100 kW and over you earn LGCs annually instead. Excludes demand-charge savings and any tax depreciation, which can shorten payback further. Confirm tax treatment with your accountant or the ATO. Sources: Clean Energy Regulator, AER DMO 2025-26, Google Solar API.
The blind spot
Why most business solar guides give the wrong reason
Most articles about commercial solar make the same three mistakes, and each one points a business owner at the wrong lever.
First, they credit the bigger system. They imply a business wins because it can fit more panels. Size helps, but it is not why business solar pays faster. A home with the same array would do worse, because it cannot use the output. The real edge is the load shape, not the kilowatts.
Second, they talk up the feed-in tariff. Consumer guides treat exports as a payday. For a business that is almost the opposite of the truth. Your load lines up with generation, so you export very little, and commercial export rates are tiny anyway, with some networks capping or charging for it. Chasing a feed-in headline leads you to oversize for a sale that barely exists.
Third, they ignore the two levers that actually move a commercial result: the 100 kilowatt certificate cliff that decides whether your rebate arrives upfront or trickles in over years, and the demand charge in dollars per kilovolt-ampere that homes never pay. Get those two right and you can change the payback by more than any panel choice. They are the heart of this page.
How commercial solar is really priced
Expert analysis: the machinery behind the payback
Your load shape is the asset, and why payback is fast
Solar economics is a spread between what a kilowatt-hour costs you and what it saves you. A business buys grid power at roughly 25 to 40 c during the day, and that is exactly when solar generates. So self-consumption sits naturally high, often around 80 to 90% for offices, retail and light manufacturing, because the air conditioning, the machines and the lights all run while the sun is up. Each of those kilowatt-hours offsets the full commercial rate rather than being exported for cents. Pair that with installed costs of about $0.70 to $1.00 per watt at commercial scale, cheaper per watt than a home, and the payback typically lands at three to five years. The load shape is doing the work, not the size of the array.
The 100 kW cliff: STCs upfront versus LGCs over years
This is the lever most business owners have never heard of. A solar system up to 100 kW earns Small-scale Technology Certificates (STCs), which your installer takes in exchange for a large discount applied upfront, the same mechanism as a home. The moment you hit 100 kW and above, you switch to Large-scale Generation Certificates (LGCs), which are paid annually on the power you actually generate, not handed over at install. That is a genuine cliff in the cash flow. A 99 kW system keeps the big upfront rebate; a 110 kW system gives it up for a slower annual stream. So a smaller system can be the better investment, which is why experienced installers often size deliberately to just under 100 kW. Source: Clean Energy Regulator.
Demand charges: the cost solar can shave that homes never see
Many business electricity plans include a demand charge, billed in dollars per kilovolt-ampere ($/kVA) on your highest power draw in the billing period, on top of the usage rate. A home never pays this. Because solar generates through the middle of the day, it can pull down your midday demand peak, cutting the demand charge as well as your usage. Getting this right can matter as much as the kilowatt-hour savings, but it depends on when your peak falls. If your demand peak is at 8am before the sun is up, solar helps less; if it is at midday with the air conditioning at full tilt, solar can shave it hard. This is worth modelling explicitly, because it is invisible on a simple usage-only payback.
Tax treatment, and why export is irrelevant for business
Two final pieces. First, a solar system is a business asset, so depreciation or the instant asset write-off may apply, improving the after-tax payback. The thresholds and rules change, so confirm the current treatment with your accountant or the Australian Taxation Office before you rely on it. Second, and counter to every consumer guide, the feed-in tariff is close to irrelevant for a business. Your load already absorbs most of the generation, so you export little, commercial export rates are small, and some networks cap or charge for export. The value is in offsetting your own daytime usage and shaving demand, not in selling power back.
What this costs real businesses
How good systems end up underperforming
The mechanism above is not theory. It is exactly how well-run businesses leave money on the table.
They size for the roof, not the load
An owner fills the whole roof, then finds the business cannot use the midday surplus. The extra panels export for cents while the upfront cost climbed for capacity that never pays. A smaller system matched to the daytime load would have returned more per dollar.
They step over the 100 kW cliff by accident
A quote comes back at 110 kW because it filled the roof, and nobody flags that this forfeits the upfront STC discount for LGCs paid out slowly over years. Trimming to 99 kW would have kept the big rebate and improved the cash flow, often for a barely smaller system.
They never check their demand charge
The usage saving looks fine on paper, but the business is on a demand tariff and the solar was never sized or oriented to shave the midday peak. A charge worth thousands a year sits untouched, when a small design change could have cut it.
They forget to re-shop the business plan
After install the business stays on the plan it had before solar. In the competitive states a business plan that balances a fair usage rate and demand charge against the export terms would have paid more than the panels' first-year difference. The plan is part of the system.
The insider insight
A 99 kW system can beat a 110 kW one
Here is the part the brochures never put in the headline. Two near-identical systems, one at 99 kW and one at 110 kW, are funded in completely different ways. The 99 kW system earns Small-scale Technology Certificates, paid as a large discount the day it is installed. The 110 kW system earns Large-scale Generation Certificates instead, paid out year by year on the power it generates. The bigger system makes a little more energy, but it gives up a large upfront rebate for a slow annual trickle. On a simple payback, the smaller system often wins.
The non-obvious truth: on commercial solar, the certificate scheme can outweigh the extra kilowatts. A system designed to sit at 99 kW captures the full upfront STC discount and keeps the cash flow front-loaded, which is why experienced installers size to just under the line on purpose. If a quote comes back at 100 kW or just over, ask what dropping to 99 kW does to the rebate and the payback before you sign. It is a question almost no buyer thinks to ask.
The practical consequence: do not let roof space alone push the system over 100 kW. Model both sides of the cliff, and bring the demand charge into the same model, because together they move the result far more than any panel brand.
Grounded in the analysis
What you should actually do
Specific moves that follow from how commercial solar is priced, not generic advice.
Size to your daytime load
Start from how much power you use during working hours, not how many panels fit the roof. A system matched to your daytime load, with self-consumption near 80%, returns more per dollar than a larger one that exports the surplus for cents. Use the calculator above to test it.
Mind the 100 kW cliff
Below 100 kW you get the big upfront STC discount; at 100 kW and over you switch to LGCs paid slowly over years. A 99 kW system often beats a 110 kW one on payback. If a quote sits at or just over 100 kW, ask what dropping to 99 kW does to the rebate before you sign.
Check demand charges and tax, then re-shop the plan
See whether you pay a demand charge in $/kVA, because solar that shaves the midday peak cuts a cost homes never see. Ask your accountant or the ATO about depreciation or the write-off. Then compare a business plan in VIC, NSW, SA, QLD or the ACT. In WA and NT the lever is sizing, not switching.
See how solar panels are really priced, or why the inverter sizing matters for a commercial system.
Current figures, last updated 2026-06-15
Australian commercial solar figures for 2026. Sources: the Clean Energy Regulator (STC and LGC schemes, zone ratings), the Australian Energy Regulator (DMO 2025-26) and the Australian Taxation Office (asset depreciation). Confirm current figures and your own tax treatment before purchase, as the rebate, tariffs and write-off rules are reviewed regularly.
The bottom line
Why this matters right now
Business solar is one of the few investments where the case keeps getting stronger. Panels keep getting cheaper, commercial power keeps getting dearer, and a business's nine-to-five load lines up with the generation almost perfectly, so self-consumption stays high and the payback stays short. The win has nothing to do with a feed-in tariff and everything to do with using your own power. Size to your daytime load, stay on the right side of the 100 kilowatt cliff to keep the upfront rebate, check whether solar can shave a demand charge, ask your accountant about the tax treatment, and in the competitive states put it all on a business plan that fits. Do that and three to five years is a realistic payback, after which the power is close to free.
Common questions
A Selectra expert answers your business solar questions
Typically three to five years for a well-sized system, faster than a home. The reason is structural: a business uses most of its power during daylight, so nearly every kilowatt-hour the panels make replaces grid power you would have bought at 25 to 40 c, rather than being exported for a few cents. High self-consumption is the lever, and most businesses have it built into their hours.
It is the line between two certificate schemes. A system up to 100 kW earns Small-scale Technology Certificates (STCs), paid as a large upfront discount on the install, the same as a home. A system of 100 kW and above earns Large-scale Generation Certificates (LGCs) instead, paid annually on actual generation rather than upfront. That changes the cash flow completely. A 99 kW system can be better value than a 110 kW one, because it keeps the big upfront rebate, which is why installers often size deliberately to just under 100 kW.
Many business electricity plans bill a demand charge in dollars per kilovolt-ampere ($/kVA) based on your highest power draw in the period, on top of usage. It is a cost homes never see. Solar that generates through the middle of the day can shave your midday demand peak, cutting that charge as well as your usage. Getting the demand side right can matter as much as the kilowatt-hour savings, so it is worth modelling both with your accountant or energy broker.
No. For a business the value is offsetting your own daytime usage, not exporting. Commercial export rates are tiny, and some networks cap or even charge for export. Because your load already lines up with generation, you export far less than a home does, so the feed-in rate barely touches the result. Build the system to use power, not to sell it.
Often, yes. A solar system is a business asset, so depreciation or the instant asset write-off may apply, which can improve the after-tax payback further. The rules and thresholds change, so confirm the current treatment with your accountant or the Australian Taxation Office before you rely on it. It does not change the core logic, but it can shorten the payback.
Yes, in the competitive states. In Victoria, New South Wales, South Australia, Queensland and the ACT you can choose your retailer and compare business plans, balancing the usage rate and demand charges against any export terms. In Western Australia (Synergy) and the Northern Territory there is no retail competition, so the lever is sizing and self-consumption rather than switching. Either way, the plan you had before solar is rarely the best one after.
