Electrical

Commercial Solar Fault Finding and Troubleshooting: A Facility Manager's Guide

Guide · Commercial solar & battery · ~5 min read

When a commercial solar system underperforms, the cost adds up quietly on your power bill before anyone notices. This guide walks facility managers through the common faults, the safe first checks, and when to bring in an accredited team.

How to Tell Your System Has a Fault

The first sign of trouble is rarely a flashing error light. More often it's a gradual slide in generation that blends into seasonal variation, so you don't catch it until the bill arrives. That's why monitoring data is your early warning system.

Compare current output against what the system produced in the same period last year, and against similar sunny days. A single string that's dropped off, an inverter sitting idle, or a battery that isn't cycling the way it should are all worth investigating before they become bigger problems.

• Generation lower than the same month last year under similar weather
• One inverter or string producing noticeably less than its neighbours
• Error or fault codes on the inverter display or monitoring portal
• A battery that no longer charges or discharges on its usual schedule
• Unexpected jumps in your grid import despite clear skies

Safe First Checks Before You Call Anyone

There are a handful of low-risk checks a facility manager can do from the ground and the monitoring portal. These won't fix a wiring fault, but they can tell you whether you've got a real problem or just a cloudy fortnight.

The hard rule: solar arrays carry DC voltage whenever the sun is up, even with the system switched off. Never open inverters, touch DC cabling, or climb onto the roof to inspect panels. That work is for a licensed, accredited installer.

• Check the inverter display or app for fault codes and note them down
• Confirm the system is actually switched on at the isolators (visual only)
• Review monitoring trends across the last few weeks for a sudden drop
• Look for obvious shading from new structures, signage or vegetation
• Check whether a grid outage or network event coincided with the drop

Common Faults on Commercial Systems

Commercial rooftops are busier and larger than residential ones, so the fault list is longer. Scale matters too: a fault on a large array like the 415kW rooftop we installed at DB Santasalo in Bulli can hide in the data unless you're tracking string-level performance.

Many issues are environmental or mechanical rather than electrical, and they build up over time on a big roof.

• Dirt, dust, bird mess and pollen reducing panel output, especially on low-pitch roofs
• Isolator and connector degradation from weather and heat
• Inverter faults, overheating or tripping on hot days
• String failures from a single damaged panel or loose connection
• Communication dropouts that leave you blind in the monitoring portal
• Battery or energy-management faults affecting charge and discharge cycles

Diagnosing the Problem Methodically

Good fault finding works from the whole system down to the component. Start with the monitoring data to narrow down whether the issue is at the inverter, a string, or the battery, then an accredited technician can test from there.

Because our team works in-house with no subcontractors, the person diagnosing the fault understands how the system was designed and commissioned. That continuity usually means a faster, cleaner diagnosis than starting cold on someone else's install.

• Isolate whether the fault sits with generation, the inverter or the battery
• Compare string outputs to find the underperforming circuit
• Use thermal imaging and electrical testing to confirm the root cause
• Check firmware and communication hardware for monitoring dropouts
• Verify the fix against baseline performance once repairs are done

When Fault Finding Becomes an Upgrade Opportunity

Sometimes a fault review surfaces a bigger question: is the system still right for how the site runs today? An ageing inverter, a tariff change, or new load on site can all mean the original design no longer earns its keep.

This is often where AI-driven energy arbitrage comes in, a battery that charges when power is cheap and discharges or exports when it's dear. Whether that stacks up depends on your tariff, your network and your load profile, which is exactly what a site review is for.

Get a Site Review From an Accredited Team

If your commercial solar is underperforming and the first checks haven't given you a clear answer, the next step is a proper site review. ATI is CEC and SAA accredited, works Australia-wide, and handles systems from 6.6kW up to the megawatt scale on real commercial sites including Garmin, Goldschmidt and a Hunter Valley vineyard.

We'll assess the fault, confirm the cause with on-site testing, and tell you plainly whether it's a repair, a tune-up or a case for upgrading. Real figures for your site come from that review, not a guess over the phone.

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