EN 50618 Electrical Cables for Photovoltaic Systems

The European standard “EN 50618 Electrical cables for photovoltaic systems” applies to cross-linked insulation and sheathing, low-smoke, halogen-free, flexible, single-core power cables. This standard is specifically designed for use on the direct current (DC) side of photovoltaic systems, between conductors and between conductors and ground, with a nominal voltage of 1,5 kV DC. The cables are suitable for use with Class II equipment. The cables are designed to operate at a normal maximum conductor temperature of 90 degrees, but a maximum conductor temperature of 120 degrees is permitted at a maximum ambient temperature of 90 degrees for a maximum of 20.000 hours. The expected service life under normal operating conditions specified in this standard is at least 25 years.

The cables specified in this standard are designed for use with a nominal voltage of 1,5 kV DC, particularly on the direct current (DC) side of photovoltaic systems, both between conductors and between conductors and ground. When used in alternating current (AC) systems, the cables have a nominal voltage of 1,0/1,0 kV. Further information on voltage ratings can be found in the standard annex (Annex A).

The single-core, flexible, low-smoke, halogen-free power cables with cross-linked insulation and sheathing covered by this standard are designed for the following purposes:

• Used in photovoltaic systems, particularly for connecting solar modules, arrays, junction boxes, and inverters on the DC side.
• Permanent outdoor installation suitable for use under harsh environmental conditions for 20-25 years.
• Some certified variants include fixed installations (indoor/outdoor), either in pipes or directly buried in the ground.
• Class II equipment (double insulated).

EN 50618 cables must withstand the following variable and challenging climatic conditions: intense UV radiation, extreme temperatures, humidity, ozone, and occasional mechanical stress.

The basic technical specifications of cables covered by this standard are as follows:

• Nominal voltage: 1,5 kV DC, maximum system voltage up to 1,8 kV DC.
• Maximum conductor temperature: 90 degrees continuously (limited operating hours are allowed at higher temperatures).
• Conductor: Flexible tinned copper (Class 5 according to EN/IEC 60228 standard), cross-sections typically between 1,5 mm² and 240 mm² (most common being 4 mm² and 6 mm²).
• Insulation and sheathing: Electron beam or silane cross-linked halogen-free compounds provide the following:
• Low smoke and zero halogen emissions in case of fire.
• High resistance to abrasion, weathering, UV rays, ozone, and chemicals.
• Water resistance (many variants meet AD8 for permanent submersion).
• Test voltage: Typically 6,5 kV AC (or equivalent DC) for 10 minutes.
• Temperature range: Generally from -40 degrees to +90 degrees (or briefly +120 degrees), some products are rated up to 120 degrees.
• Fire performance: Low smoke, halogen-free.
• Other compatible standards: For global acceptance, it is frequently tested according to IEC 62930, UL 4703 and similar standards.

Typical applications of this standard include:

• Solar panels are connected to each other in arrays.
• DC cable connections from modules to combiner boxes or inverters.
• Ground-mounted, rooftop, or floating solar energy systems.
• Both ground-based and soilless photovoltaic systems.

The EN 50618 standard is critically important for photovoltaic (PV) systems, particularly in Europe and increasingly worldwide, as it directly addresses the unique and challenging conditions that DC solar cables encounter throughout their service life of over 25 years. The main reasons why this standard stands out and is considered indispensable are as follows:

• It ensures long-term safety and reliability in harsh outdoor environments: PV cables are exposed to extreme conditions year-round: intense UV radiation, wide temperature variations (minus 40 degrees to plus 90 degrees or higher peaks), ozone, humidity, abrasion, occasional submersion in water, and mechanical stress from wind, snow, or installation. This standard mandates rigorous testing for:
• UV and weather resistance (prevents cracking, brittleness, or deterioration).
• Ozone resistance.
• Thermal aging and short-term overloads (up to 120 degrees for limited periods).
• Mechanical properties (wear, cut, flexibility).

Without these, cables can fail prematurely, leading to arc faults, ground faults, reduced efficiency, fires, or system failures. All of these are expensive and dangerous in large-scale solar power installations.

• Supports higher system voltages (1,5 kV DC): Modern PV systems have shifted from approximately 1 kV to 1,5 kV DC (maximum 1,8 kV) to reduce losses, use thinner cables, and lower system balancing costs. This standard was specifically developed for this transition and replaces the old standard (which was limited to 1 kV DC).

Higher voltage capacity, better efficiency, and lower installation costs are achieved, but require tighter insulation and dielectric strength. This standard mandates it.

• Fire safety and low smoke/zero halogen performance: Solar energy installations often involve long cable runs near buildings, roofs, or residential areas. This standard requires halogen-free, low-smoke compounds, limiting toxic gas release and smoke in the event of a fire. This complies with modern building regulations, enhances evacuation safety, and is often a mandatory requirement in the EU for insurance, grid connection, and project certification.
• Regulatory and market compliance (particularly in Europe): This standard is a compliant European standard referenced in CENELEC and linked to EU directives. The international module safety standard IEC 61730 explicitly requires PV cables to comply with the EN 50618 standard. In EU tenders, large-scale projects, rooftop installations, and grid-connected systems, EN 50618 marking is frequently mandatory for acceptance, certification, insurance coverage, and regulatory approval.

Consequently, the EN 50618 standard is recognized in Europe and many international markets as the modern gold standard for reliable, long-lasting DC solar power cables. This standard is a critical element of safe and efficient photovoltaic energy production.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the EN 50618 standard.