July 7, 2026
By Will White | Anyone in solar knows sites are built to withstand challenging weather. Wind, heat, hail, standing water, freeze-thaw cycles – none of this is unusual, and none of it automatically becomes a fault that costs you output.
The trouble is what those harsh conditions leave behind. The obvious damage gets attention first. The quieter damage often doesn’t: insulation worn through at a contact point, a ground fault that appears only in wet conditions, a string that stays offline because the team can’t justify hours of disruptive fault-finding while the rest of the plant needs required maintenance.
That’s where resilience gets more interesting than simple survival. For operators, the real question is often less “Did the site make it through?” and more “What did that event start that we still haven’t found?”
How most ground faults begin
Ground faults aren’t a corner case in solar operations and maintenance (O&M). They’re part of the background workload of running real sites, and they rarely stem from exotic failure modes. More often, they start with an ordinary detail that went wrong or didn’t hold up: wire routed poorly, insulation damaged during installation, cable tied too tight against the rack, movement over time, moisture, abrasion, or animal damage.
Wire management is worth singling out because it tells you more than just where a fault came from. An inspector walking up to an installation can look under the array before going near the electrical system and often get a clear picture of the construction quality. Dangling wires are a reliable predictor of broader quality problems. The inverse is also true: conductors neatly routed and affixed properly tend to indicate a system that was built carefully throughout. On all types of systems, it’s about routing discipline – wires running over racking edges, or secured so tightly they can’t move without abrading, are faults already in progress.
Resilience begins before the first fault alert. It’s shaped by how cleanly the array was built, how well the conductors were secured and protected, and whether routine inspections catch wear before it turns into lost generation and invasive troubleshooting.
Why troubleshooting stops short
In practice, the hard part isn’t confirming that something is wrong. It’s narrowing the fault down far enough to fix it without turning the day into a prolonged search.
When an inverter trips, the crew can usually identify the affected combiner quickly enough to get most of the plant back in service. Shut the combiner off, bring the inverter back online – you’ve gone from the whole system down to a much smaller section of it offline. That’s the immediate priority dealt with. But the fault itself isn’t resolved. It’s parked.
Finding which string in that combiner carries the fault is slower. Identifying the precise fault point in that circuit is even slower. At that stage, the work becomes intrusive: you’re unwiring strings one by one, checking each in isolation, working around conductors that are live because there’s no way to de-energize the modules in daylight. Murphy’s Law applies reliably here – it’s rarely the first strings you test. On a large combiner with twenty or more strings, that search can absorb hours if not days, and the whole time you’re handling energized DC with no clean way to make it safe.
That’s why troubleshooting usually stops before it reaches the fault point. Teams take the affected string offline, bring the rest back, and move on. It’s the right call under operational pressure.
The job stops sprawling
Once you can place the fault precisely, the job stops sprawling. You’re not unwiring healthy strings to reach the bad one, not repeatedly isolating and re-testing, not leaving a string offline simply because chasing the exact fault point would take the rest of the day. That last point matters more than it might look on paper. A combiner box left offline for a month – as happens more often than it should – isn’t just a deferred job. It’s a slice of capacity the site is running without, compounding quietly until someone decides it’s finally worth the disruption to resolve it.
It also changes what’s possible with the harder fault classes. High-resistance and intermittent faults are hard enough when you know where to look. They become much harder when the search itself absorbs the maintenance window. A precise location gives the crew something to act on rather than something to keep working around – and means intermittent faults can be pursued properly when conditions make them visible, rather than left on the list indefinitely.
The cost consequences of getting this wrong are real and cumulative. Ground faults are a significant driver of the industry’s corrective maintenance burden. Every fault deferred rather than resolved adds to that cost, and it compounds across a fleet. But while the financial math is compelling, the business case for precise fault resolution sits underneath a more serious concern.
The fire department shouldn’t be your early warning system
A ground fault can energize racking and module frames that nobody expects to be live. If the bond to ground isn’t solid and a crew member touches that metalwork, they become the path to ground – that’s where shocks and electrocutions happen. Separately, where the connection between conductor and metal is resistive rather than clean, the current arcs. Arcing generates heat. On a ground-mounted site with dry vegetation underneath, that heat finds fuel. There are documented cases where repeated arc faults were igniting grass fires under arrays frequently enough that the local fire department forced the operator to institute a strict vegetation-management plan – and other sites where operators till the earth around the array perimeter as a permanent firebreak.
Solar ABCs research into ground fault protection failures following real fires at utility-scale sites in the US found that faults on grounded conductors can persist undetected for extended periods, establishing a new “normal” condition that leaves the system’s protection unable to interrupt a second fault.
Beyond the immediate safety exposure, every amp going to ground isn’t going to the inverter. The financial loss is straightforward: unresolved ground faults reduce generation, and the more faults accumulate across a site, the wider that gap becomes. ESFI data on workplace electrical fatalities covering 2011 to 2023 shows that ground faults accounted for 4% of all workplace electrical fatalities in the US – a reminder that these aren’t abstract electrical events.
Resilience, in other words, is a maintenance issue as much as a weather one. The headline event may have passed. The harder question is whether the electrical damage it left behind is still in the system – waiting to trip again or put the next crew working that section at risk.
Find it. Fix it. Move on.
Ask the technician who spent three hours unwiring strings in a combiner box, working around live DC in full sun, only to find the fault in the last one they tested. Was that a good use of a maintenance window? Was the site better protected for it?
That’s the operational reality that precise fault location tools address. Your crews get to the fault, fix it, and move on – without leaving more offline than they have to, without the hours of exposure that come with searching by elimination. On a US solar fleet that added 43 GW in 2025 alone and will keep growing, that difference compounds across every site, every maintenance window, every fault that either gets resolved properly or sits in the system waiting for a better day that rarely comes.
Will White is senior product manager at Fluke Corporation.
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