When undertaking photovoltaic projects, everyone focuses on modules and inverters, yet frequently overlooks the seemingly trivial cables. Cutting costs on cables in the early phase may result in circuit tripping, power generation degradation and even fire hazards down the line.

PV cables are the "blood vessels" of a power station. Direct current generated by solar modules is transmitted to inverters through cables. Rooftop installations are exposed to intense sunlight, large day-night temperature differences, wind-induced vibration, together with high-voltage direct current. Ordinary wires are simply incapable of surviving such harsh operating conditions.

Two extreme approaches prevail in the industry. One is to adopt high-end PV cables for all application scenarios, which pushes up costs and erodes project profits. The other is to chase low prices by replacing dedicated PV cables with conventional wires. No defects show up in the short run, but sheath cracking will occur after several years of operation, creating hidden risks of DC arcing and fire.

For PV cables, higher price does not equal better quality, nor should costs be recklessly reduced. The right material-selection principle for engineers is to distinguish AC and DC circuits, match cables to installation conditions, ensure adequate specifications where necessary without downgrading, and avoid unnecessary over-specification.

01 What Makes Dedicated PV Cables Unique?

Conventional wires are designed for indoor alternating-current conditions. They tend to age and turn brittle under outdoor solar radiation and cannot withstand high-voltage DC for photovoltaic systems. Once insulation suffers damage, direct current can easily generate inextinguishable electric arcs, a major cause of PV-related fires.

Dedicated PV cables are specially optimized: UV-resistance, resistance to high and low temperatures, tolerance to repeated vibration and bending. Matched with the 25-year design lifespan of solar modules, they deliver flame-retardant safety and are purpose-built for outdoor high-voltage DC environments.

02 Tell AC and DC Circuits Apart to Avoid Wrong Selection

DC side (modules to inverters)

Dedicated PV cables are mandatory for outdoor exposure. Even if cables run inside conduits with high internal temperatures, PV cables are still recommended instead of ordinary wires.

AC side (after inverters)

Current has been converted to alternating current, so dedicated PV cables are not required. Use ordinary flame-retardant cables for indoor cable trays and conduit routing; deploy armoured cables for direct underground burial or locations vulnerable to mechanical damage for enhanced protection.

03 Four Common Missteps in Cable Selection

Myth 1: Ordinary wires can replace PV cables as long as the conductor cross-section is sufficient

A large-enough cross-section does not guarantee weather resistance or voltage withstand capability. Outdoor ageing and cracking will create severe safety risks.

Myth 2: Uniformly apply PV cables across all circuits without differentiating AC and DC

Over-specification on the AC side brings unnecessary project costs.

Myth 3: Select cables exactly matching the operating current with no safety margin

High summer temperatures reduce cable current-carrying capacity. Long-term near-full-load operation accelerates ageing and overheating. Appropriate safety margins are essential for reliability.

Myth 4: Focus only on cables while neglecting connectors

Numerous failures originate from connectors. Poor-quality or improperly crimped connectors are prone to overheating and burnout. Always deploy qualified dedicated connectors and follow standard construction procedures.

04 Core Principles for Material Selection

• Dedicated PV cables form the safety baseline for outdoor DC circuits and cannot be economized on;
• Select conventional cables for the AC side as required; refrain from blind upgrade to PV cables;
• Reserve sufficient margins in selection and implement robust protection for harsh environments;
• Cables and connectors are equally critical; reject non-standard and inferior products.

Closing Remarks

Photovoltaic systems involve concealed work, with cables tucked within gaps of mounting supports. Cost savings made on cables in the early stage may later translate into power generation losses, rework and maintenance, or even safety accidents. Choosing the right PV cables is an investment in 25 years of safe, efficient power generation.