A warehouse has the perfect roof. That is the problem.
Warehouses get quoted the largest systems in commercial solar, for the simple reason that they have the most roof. But the value of solar comes almost entirely from power you do not buy, not power you sell — and a single-shift warehouse with lighting, a few doors and some charging can have a load far smaller than its roof suggests. Sized to the roof, that system exports its best hours for a fraction of what it would have been worth used on site.
Reviewed by the Mission Green commercial team · Updated August 2026
Size to the load,
not to the roof.
The most common and most expensive mistake in warehouse solar.
Solar earns its return by displacing electricity you would otherwise buy at your retail rate. Exported electricity earns a feed-in rate, which across Australia in 2026 is generally a small fraction of what you pay to import.
So the useful size of a system is set by how much of its output you can consume as it is generated. On a warehouse that is often much less than the roof would hold. A single-shift distribution site with high-bay LED lighting, some dock equipment and an office can draw far less than the roof implies, and the gap between the two is exported at low value.
This is why a proposal should start with your interval data and not with a satellite image of your roof. If the first number in a conversation is kilowatts and the second is roof square metres, nobody has looked at your consumption yet.
Three roof questions
that come before panels.
Warehouse roofs are large, and they are not always ready.
Can it take the load?
Large-span industrial roofs are engineered lean. Additional dead load and wind uplift on a large array is a structural question, and the answer comes from an engineer rather than an installer.
How long has the sheet got?
Solar is a twenty-plus year asset. Putting it on sheeting with ten years left means paying to remove and reinstall it. Roof condition is a scheduling question, not a detail.
Skylights and fragile sheet
Warehouse roofs commonly carry skylights and translucent sheeting. They affect usable area, safe access and the cost of maintaining the array for its whole life.
None of these stop a project. All of them change the cost or the timing, and all of them are cheaper to discover before a contract than after one.
What the network
will let you export.
A large array on a modest connection is a conversation with your distributor.
Export limits are set by your distributor and are a real constraint on large commercial arrays. A system sized well beyond site load may be permitted to generate but not to export freely, which removes even the low-value fallback the oversizing relied on.
Worth knowing: export arrangements can differ by system size in ways that are not intuitive. SA Power Networks' published structures, for instance, apply export tariffs to customers with 0-30 kW export capacity and state that systems with more than 30 kW export capacity are not subject to an export tariff. That is one distributor's structure and yours will differ — the point is that these rules have thresholds, and the thresholds are worth checking before you settle on a size.
Certificates have thresholds too. A system stays in the small-scale scheme only at 100 kW or less and under 250 MWh a year, and warehouse roofs are exactly where projects cross that line without anyone checking the output test.
When a warehouse
is actually a great site.
The load can be created, and increasingly is.
Refrigerated or temperature-controlled space transforms the picture. Continuous cooling load is the best possible match for solar generation, and it turns a big roof from a liability into an asset.
Materials handling charging. Forklift and equipment charging is a genuine daytime load, and unlike most loads it is schedulable — which means it can be moved into generating hours deliberately.
An EV fleet. Vehicle charging is the largest new controllable load most warehouses will add this decade. Charged during the day it can consume solar that would otherwise export; charged at 5pm as drivers return it can create a demand peak that bills for a year. The difference is scheduling, not hardware.
A second shift. Any extension of operating hours into daylight improves the match directly.
So what should
your business actually do?
Short version.
Ask for the self-consumption percentage, not just the system size. What proportion of generation does the proposal assume you use on site? If it is low, you are being sold export at feed-in rates.
Get the roof assessed before you commit to a size. Structure and remaining sheet life set the real ceiling far more often than the panel count does.
Check the certificate and export thresholds for the size being proposed. Both have hard edges, and crossing one unintentionally changes the economics after the fact.
If you are adding charging or refrigeration, model it in. Future load changes the right system size substantially, and it is much cheaper to allow for it now than to add a second array later.
If you lease the building, settle the ownership question first. Warehouses are overwhelmingly tenanted, and a system on a roof you do not own needs its terms written down before installation.
Warehouse solar:
your questions, answered.
As large as your load can consume during generating hours, not as large as the roof will hold. Solar earns its return by displacing electricity at your retail rate; exported energy earns a feed-in rate that is generally a small fraction of that. A single-shift warehouse frequently has far less daytime load than its roof area suggests, so a system sized to the roof exports much of its best output at low value.
That is a question for a structural engineer, not an installer. Large-span industrial roofs are engineered efficiently, and a large array adds both dead load and wind uplift. It is also worth checking the remaining life of the roof sheeting, because solar is a twenty-plus year asset and installing over sheeting with ten years left means paying to remove and refit the array.
Only within the export limit your distributor sets, and those limits are a real constraint on large commercial arrays. Export arrangements can also change with system size in ways that are not obvious — SA Power Networks, for example, publishes export tariffs for customers with 0 to 30 kW export capacity and states that systems above 30 kW export capacity are not subject to one. Yours will differ; the point is to check the thresholds before choosing a size.
Less than you would hope. Demand charges are set by a short peak measured in kVA, and on some tariffs that peak window falls outside useful generating hours. Solar reliably reduces the energy you import and does not guarantee your worst half-hour. On a warehouse the more effective demand lever is usually scheduling — particularly of charging.
Only if there is something specific for it to do — covering a demand peak that sits outside generating hours, or supporting critical load. A battery bought to soak up excess generation on an oversized system is solving a problem created by the sizing. Fix the sizing first.
Model it now. Both create substantial daytime load and both change the right system size materially. Charging in particular is schedulable, which makes it one of the few loads you can deliberately move into generating hours — or accidentally leave sitting in your demand peak window.
Where these figures come from.
We do not publish system prices on these pages. The number that decides a warehouse project is your load profile, not the cost per watt, and anyone quoting the second without asking for the first is guessing.