Small faults, big losses: The O&M challenge facing SA solar

South Africa’s rapidly expanding commercial solar and battery fleet is creating a less visible challenge: keeping installed assets performing as designed over their operating lives.

According to Rhino Energy Solutions (RES) CEO, Rogan Davies, relatively minor faults, including tripped breakers, battery imbalance, degraded cabling and communication failures, can remain undetected for days or months, reducing generation and eroding project returns.

“Everyone competes on the installation," he argues. “The panels, the price per watt, the time to energise. But a solar asset is a 20-to-25-year commitment, and almost every commercial failure we see happens after commissioning, not during it. Operations and maintenance aren’t a support function bolted onto a project; it's the single biggest lever on whether that project ever pays back what the business case promised.”

The industry's blind spot

Most feasibility studies and payback calculations model a solar plant’s output as a smooth, predictable curve: a small annual degradation rate applied evenly for two-plus decades. Davies says that assumption depends on a level of disciplined maintenance that a large share of the installed base simply isn't getting.

In practice, output loss on a poorly maintained system often comes from sudden, preventable faults rather than gradual panel degradation: a tripped breaker nobody notices for days, a battery bank drifting out of balance or cabling degraded by foot traffic. Without active monitoring, these faults can remain invisible until they appear as a generation shortfall, an unplanned outage or a safety risk.

Drawing on its O&M call-out history across industrial, commercial and agricultural sites, RES says it has observed the same pattern recur regardless of sector: a minor, catchable issue goes undetected for weeks or months before it surfaces as a more serious problem.

The financial impact compounds quickly. Davies estimates that a mid-sized commercial plant can lose 10–15% of a month's yield to a single unmonitored fault, and that an unnoticed breaker trip alone can cost around R20,000 a day in unrecovered generation and emergency backup costs. None of this shows up in a feasibility study. All of it shows up in the client's actual return.

Five recurring failure patterns

Davies says RES’s call-out data points to the same handful of root causes across the industry:

• Thermal derating from clogged fans and poor plant-room ventilation, which silently caps output during peak sun.
• Grid instability and poor municipal power quality, causing nuisance breaker trips and premature degradation of surge protection devices.
• Communication failures between plant controllers, meters and inverters over degraded networks, which distort logged generation and billing data.
• Incompatibility between older on-site diesel generators and modern PV/EMS hybrid controllers, causing inverters to reject the backup power source entirely.
•  Loose bolted electrical connections that degrade over time into arc-fault risks if never inspected.

Davies flags controller-level coordination between BESS, energy management system (EMS) software and legacy backup generation as a growing concern as sites scale up and combine technologies. As more sites pair solar, batteries and standby generators to manage tariffs and grid instability, mismatches between these systems are producing more nuisance trips and rejected power, a problem he expects to become more common as hybrid systems become the default rather than the exception.

The economics of waiting

Davies estimates that preventative O&M and asset management typically cost between 1–2% of a plant's capital cost annually.

“Reactive repair such as emergency labour rates, expedited parts, and the yield lost while a fault goes unaddressed typically runs three to four times higher than catching the same issue early.”

Over a 20-to-25-year operating life, small losses that persist unnoticed can undermine the generation assumptions on which project payback calculations were originally based.

The next standards challenge

RES argues South Africa's solar sector is repeating a pattern seen in other fast-growing infrastructure markets: installation capacity scaled quickly, while the maintenance discipline needed to sustain that installed base over decades has lagged. As the country's cumulative solar and BESS fleet grows, Davies says O&M needs to be treated with the same rigour, standards and professional recognition as engineering and installation.

That is the message Davies intends to bring to industry conversations ahead of his panel discussion at SAPVIA in October: “That the next phase of the sector's credibility with clients, funders and regulators will be won or lost on operating performance, not installation numbers.”

What preventative O&M looks like

Active monitoring can identify problems such as breaker trips and abnormal generation before they develop into prolonged losses. Thermal imaging can reveal hotspots, micro-arcing and deteriorating electrical connections, while routine mechanical and electrical inspections can identify ventilation, cabling and termination problems before they cause outages or safety risks.

“The faults we see all have the same shape: something small and catchable that nobody was looking for, sitting for months before it becomes an outage or a safety risk. That's not a technology problem, it's a maintenance-model problem and it's the single biggest reason a solar investment underperforms its business case.” says Davies.

“We tell every prospective client the same thing before they sign: ask your EPC partner what happens after commissioning, not just what happens during it. That single question tells you more about your future returns than almost anything in the proposal.” Davies adds.

A practical maintenance cadence

RES recommends the following inspection and maintenance cadence as a baseline for commercial and industrial solar and BESS sites, offered as a starting reference for businesses assessing their own or a contracted O&M programme: