Battery Storage

Islanding and Backup Power for Commercial Sites: Keeping Operations Running During Outages

Guide · Commercial solar & battery · ~5 min read

When the grid goes down, most solar systems shut down with it. Islanding and proper backup design let your commercial site keep critical loads running, so an outage doesn't bring the whole operation to a halt.

Why Your Solar Switches Off When the Grid Fails

It surprises a lot of business owners: you've got a big rooftop array, the sun is shining, the grid goes down, and your site goes dark anyway. That's by design, not a fault.

Grid-connected inverters are required to shut down during an outage, a safety feature called anti-islanding. It stops your system back-feeding power into the network while linesworkers might be repairing it. Without extra equipment, your solar simply disconnects until the grid returns.

• Standard grid-tied inverters must disconnect in an outage
• This protects utility workers and network equipment
• Solar generation stops even when conditions are perfect
• Backup capability has to be engineered in deliberately

What Islanding Actually Means

Islanding is when your site safely disconnects from the grid and runs as its own self-contained 'island' of power. The key word is safely: the system isolates from the network first, then supplies your loads from solar and battery.

Doing this properly needs the right inverter architecture, protection equipment and switching. It's not something you bolt on as an afterthought, which is why backup is best designed in from the start, or carefully retrofitted by a team that understands the switching logic.

Batteries Are the Missing Piece

Solar alone can't deliver reliable backup. Clouds, night and sudden load changes make it too variable to run a site on its own. A battery gives you a stable source that can hold voltage and frequency while solar does the charging.

At ATI we also design batteries to earn their keep the rest of the time through AI-driven energy arbitrage, charging when power is cheap and discharging or exporting when it's dear. That means the same asset supporting your backup can be working on your energy bill day to day, depending on your tariff and network.

• Batteries provide the stable base that backup needs
• Solar recharges the battery through an extended outage
• The same battery can run energy arbitrage when the grid is up
• Sizing depends on which loads you need to keep running

Decide What You Actually Need to Keep Running

Backing up an entire commercial site is rarely the most sensible approach. The smarter question is: which loads can't afford to stop? Refrigeration, servers and data, security and access control, EFTPOS and comms, or a specific production line can often be the real priorities.

By separating essential circuits from the rest, you can right-size the battery and backup setup around what matters. That usually gives you a more practical, better-value system than trying to carry every load through every outage.

• Cold storage and refrigeration to protect stock
• Servers, networking and point-of-sale systems
• Security, lighting and access control
• Critical process or production equipment

Design and Compliance Considerations

Backup and islanding touch on switchboard design, protection settings, standby generation if you have it, and the way your system transitions between grid and island modes. Done poorly, it can trip at the worst possible moment or fail to isolate correctly.

We're CEC and SAA accredited and run everything with our own in-house team, no subcontractors, so the switching logic, protection and commissioning are handled by the people who designed it. We work across Australia and scale from 6.6kW through to MW, with commercial projects like the 415kW rooftop at DB Santasalo in Bulli behind us.

The Right Setup Comes From a Site Review

Every site is different: your critical loads, switchboard layout, existing solar, tariff and network conditions all shape what good backup looks like for you. Real numbers on resilience and savings come from looking at your actual setup, not a rule of thumb.

If keeping operations running through outages matters to your business, a site review is the sensible first step. We'll map your essential loads, look at islanding options and show you how a battery can both back you up and work on your energy costs.

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