Commercial Solar

How to Right-Size a Commercial Solar and Battery System for Your Business

Guide · Commercial solar & battery · ~5 min read

Getting the size right is the difference between a solar and battery system that quietly pays its way and one that under-delivers or sits half-idle. Here's how we approach sizing for commercial sites across Australia.

Start With How You Actually Use Power

Right-sizing begins with your consumption, not the roof. Before anyone talks panels, we want to understand when your business draws power, how much, and how that shifts across the day, week and seasons.

A workshop running heavy machinery from early morning looks nothing like an office with an afternoon air-con peak, or a cold store that runs around the clock. Each of those calls for a different balance of solar and storage.

• Your daily and seasonal load profile, ideally from interval data on your bills
• When your peaks land, and whether they line up with daylight
• Base load that runs overnight or on weekends
• Any planned changes, like new equipment, EV charging or an expansion

Read Your Tariff Before You Size Anything

Your tariff structure shapes the whole design. A flat rate, a time-of-use tariff and a demand tariff each reward different behaviour, so the right system for one site can be the wrong one next door.

Time-of-use and demand charges are where storage earns its keep, because shifting load away from expensive periods can be significant. The exact benefit depends on your tariff and network, which is why we model it against your real numbers rather than guess.

Sizing the Solar Array

Solar is usually sized to cover as much of your daytime load as makes sense for your roof, shading and tariff. Oversizing so you export large volumes often isn't the sweet spot, because export returns tend to be modest compared with offsetting what you'd otherwise buy.

We also work within practical limits: available roof area and orientation, structural capacity, switchboard and network constraints. ATI scales from 6.6kW through to MW-scale rooftops, so the array is built to the site rather than a fixed template. Our 415kW rooftop at DB Santasalo in Bulli is one example of matching a large array to a genuine industrial load.

• Usable roof area, pitch, orientation and shading
• Structural and switchboard capacity
• Network export limits that may apply at your connection
• How much daytime load the array can realistically offset

Sizing the Battery

Battery sizing is about what you want it to do. Shifting cheap daytime solar into expensive evening periods, trimming demand peaks, and holding reserve for outages all point to different capacities.

Bigger isn't automatically better. A battery that's too large for your load can sit partly unused, while one that's too small won't cover the periods that matter most. The aim is storage that cycles usefully most days against your tariff.

Where AI Energy Arbitrage Changes the Maths

A static battery just stores solar. An AI-driven system actively plays the market: charging when power is cheap and discharging or exporting when prices are dear. That can shift the ideal battery size, because the storage is working harder across more of the day.

This is ATI's core differentiator, and it means right-sizing isn't only about covering your load. It's also about how much value the battery can capture by trading against price movements on your tariff and network.

Get the Numbers From a Site Review

Every figure that matters to your sizing comes from your site: your load data, your tariff, your roof and your goals. Rules of thumb are a starting point, not a design.

ATI runs an in-house team across Australia, CEC and SAA accredited, with no subcontractors, so the people who size your system are the ones who install it. If you'd like your consumption and tariff reviewed properly, we're happy to take a look and show you what the right size looks like for your business.

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