The Hidden Variable in Solar Reliability: Why PV Connection Failures Are Increasing Globally

For the past decade, the solar industry has celebrated capacity milestones — gigawatts installed, record-low tariffs, and unprecedented project scale. But behind the impressive numbers, a quieter challenge has begun to surface.

Across markets in Europe, the Middle East, Australia, and Southeast Asia, one pattern keeps emerging from failure investigations:

More and more system failures originate not from modules or inverters — but from the connection layer.

And yet, this remains the least discussed part of the system.

01. The industry has a “connection blindness” problem

Walk into any solar conference and you’ll hear discussions about module efficiency, tracker optimization, AI-based O&M, and inverter topology.

But mention cable insulation behavior after 5,000 hours of UV exposure, or the impact of ±10% concentricity deviation on connector heating, and the room falls silent.

Why?

Because the industry is optimized for procurement, not engineering reliability.
Cables and connectors represent less than 3% of project CAPEX — and are treated accordingly.

Yet the global data tells a different story.

02. In incident databases worldwide, the smallest components cause the largest problems

• In the UK, BRE’s investigation showed DC connectors as the most common ignition point in PV fires.

• The Netherlands’ 2023 national mapping linked a high proportion of PV fires to wiring and connection issues.

• Australia’s Clean Energy Regulator reports increasing defects originating from DC isolators and cable joints.

Across regions, the pattern is consistent:

The connection layer — cables, connectors, terminations, isolators — is becoming the failure hotspot.

Not because these components are inherently weak, but because the industry underestimates how tightly their reliability is tied to manufacturing consistency, materials science, and installation tolerance.

03. Why connection failures are rising today (and will worsen without intervention)

Here are the three forces behind the trend:

1) System size has outgrown connection design margins

Large string inverters + higher currents + longer strings =
smaller thermal tolerances at every joint.

Even minor dimensional deviations now matter.

2) Market pressure has pushed cable quality to extremes

Global demand has increased faster than high-grade polymer supply.
The result? A wider spread between “compliant on paper” and “reliable in the field.”

A cable that passes a 720-hour UV test is not the same as one that survives 1,500 hours — but both may be “certified.”

3) Installation complexity has increased, but field control has not

Modern systems involve:

• multi-MPPT string routing

• dense layouts

• higher rooftop temperatures

• tighter conductor bending radii

Small mistakes now create disproportionately large risks.

04. The industry needs to rethink what reliability actually means

For the past decade, “reliable” has meant meeting minimum standards.

But minimum standards were designed for:

• older, smaller systems

• lower string currents

• milder field temperatures

We now run systems closer to their physical limits.

This demands a new definition:

Reliability today means having safety redundancy — not just compliance.

Redundancy in:

• material aging resistance

• manufacturing consistency

• thermal stability

• error tolerance in installation

• traceability across batches

Without redundancy, even a compliant product becomes a field liability.

05. The connection layer will decide the future performance of solar assets

As PV portfolios scale into tens of gigawatts, asset managers are beginning to confront a difficult truth:

The long-term performance curve of solar assets is now limited by components once considered trivial.

Every failure in the connection layer:

• causes disproportionate downtime

• requires skilled remediation

• increases insurance complexity

• erodes system IRR

And unlike module degradation, connection failures are rarely gradual.
They happen suddenly — often catastrophically.

06. What comes next (and what the industry must do)

To prevent a global wave of avoidable failures, the industry must shift from:

“Is the product compliant?” → “Is the product engineered for long-term stability under real-world stress?”

This means:

• valuing manufacturing stability as much as nameplate ratings

• treating cable/connector selection as a reliability investment

• designing projects with connection redundancy in mind

• demanding deeper testing and batch-level traceability

• integrating data from asset portfolios into procurement decisions

In other words:

We need to think of PV connections not as commodities, but as the backbone of system longevity.

Conclusion

Solar deployment will continue accelerating.
But the next stage of the industry’s maturity won’t be defined by terawatts installed — it will be defined by how well we manage the smallest, most fragile, and most overlooked parts of the system.

Because in the real world, the future of clean energy won’t be decided by capacity.

It will be decided by connection reliability.