Design, Installation, and Operation of PV Systems with Zero Fire Risk
This document presents a comprehensive approach to the design, installation, and operation of photovoltaic systems that eliminate the risk of fire. The study is based on the latest scientific research, international standards, and analysis of actual fire incidents. The application of the described solutions allows for the creation of a PV system that will remain safe throughout its entire operational period – 30 years and more.
Why do fires occur in PV installations?
Photovoltaic installations, despite many advantages, carry a real fire hazard. This results from several fundamental factors:
A fire in a PV installation is not a matter of chance or a random event. It is always a consequence of a specific chain of events, which begins with an installation, material, or design defect.
Most common causes of ignition
MC4 Connectors
Inaccurate crimping, mixing manufacturers, contact corrosion, and contamination lead to increased contact resistance → localized heating → electric arc formation.
DC Cables
Insulation abrasion, mechanical damage, rodent chewing, excessive bending – lead to short circuits or open circuits → sparking → ignition.
PV Modules
Hot spots, bypass diode damage, microcracks in cells, moisture penetration – lead to localized overheating → ignition of PET film (in Class C modules).

IMPORTANT! A fire in a PV installation occurs much faster than commonly assumed. The time from arc initiation to full ignition is only 0.1-1 second, not 10-30 seconds. This means that no active detection systems (AFCI, RSD) are able to react quickly enough.
Chain of events leading to fire
Below is the full sequence of events leading to fire, with precise physical and temporal data:
The above data shows why fire prevention in PV must be based on prevention, not reaction. Most AFCI and RSD systems react after 0.5-1 seconds, i.e., when the fire is already developing.
Physical parameters of materials in PV installations
The above data clearly shows that an electric arc with a temperature of 3000-6000°C is capable of instantly igniting practically any material used in PV installations, with the exception of glass.
Energy Balance of Fire Ignition
To understand why PV fires ignite so quickly, let's analyze the energy balance:
Conclusion: The arc energy is sufficient to instantly heat and thermally decompose several hundred milligrams of polymer, leading to rapid ignition.
Role of Distance from Flammable Materials
The heat flux density from a point source (e.g., an arc) decreases with the square of the distance:
q''(r) = \frac{\varepsilon \sigma (T_s^4 - T_{amb}^4) A}{4 \pi r^2}
where:
  • q"(r) heat flux density [W/m²]
  • ε emissivity (~0.5 for arc plasma)
  • σ Stefan-Boltzmann constant (5.67·10⁻⁸ W/m²·K⁴)
  • Tₛ source temperature [K]
  • Tₐₘᵦ ambient temperature [K]
  • A source surface area [m²]
  • r distance from source [m]
For an arc with a temperature of ~3000°C and an effective surface area of 5-10 mm², the heat flux density as a function of distance is:
The radiant ignition thresholds for most roofing materials are 10-20 kW/m². This means that a distance of 15 cm reduces the heat flux to a value 100-400 times lower than the ignition threshold.
Installation Standards and Legal Obligation to Follow Manufacturer Recommendations
Legal and Technical Basis
Every electrical device – including photovoltaic modules, inverters, connectors, and protection devices – must be installed in accordance with the manufacturer's technical documentation. This is not a matter of choice or industry practice, but a legal obligation resulting from:
  • Low Voltage Directive (LVD 2014/35/EU),
  • VDE-AR-E 2100-712 standard and other national safety regulations,
  • the general principle of installer liability (Consumer Rights Charter, Civil Code).

Consequence: any installation not in accordance with the manufacturer's instructions means the loss of the device's safety certification, and thus – in case of fire – full civil and criminal liability for the installer.
Minimum Distance Between Module and Roof
Most manufacturers require a clearance of ≥10 cm under the module for thermal safety.
In the American market, an even stricter value applies: ≥11.5 cm (NEC + UL).
Reason: with less clearance, the module's operating temperature increases by 10–20°C, which leads to:
  • increased resistance of wires and connectors,
  • accelerated material degradation,
  • increased risk of fire initiation at a short circuit point or due to an electric arc.
Conclusion: 10 cm is not a "recommendation," but a condition for safe operation. Non-compliance is equivalent to faulty installation.
In light of physical calculations and studies of PV installations that caught fire, the minimum safe distance should be ≥15 cm for pitched roofs and 30-40 cm for flat roofs. These values ensure adequate fire safety even after a long period of operation.
Dimensions and Strength of Mounting Clamps
Dimensions
The minimum length of side and middle clamps is specified by module manufacturers usually ≥75 mm.
Materials
Clamps must be made of anodized aluminum or stainless steel with strength compliant with Eurocode.
Why this is crucial:
Point Pressure
Shorter clamps exert point pressure on the glass → risk of cracking and micro-damage
Uneven Force
Uneven pressure causes "trapezing forces," leading to micro-arcs and overheating of the EVA film
Deformation
Too thin clamps can deform, causing connections to loosen and resulting in short circuits
Cables and Wire Runs
The standard requires that wires be routed in accordance with the manufacturer's manual for modules and MC4 connectors.
Key points:
  • wires must not hang loose or touch the roof surface,
  • they must be secured with metal clips resistant to UV and temperature,
  • cables must be routed to avoid forming inductive loops and overheating points.
Course of a Typical PV System Fire
To understand how to effectively prevent fires, let's analyze the sequence of events in a typical PV system fire:
Phase 1: Initiation (0-1 second)
1
Faulty Contact
Improperly pressed MC4 connector, frayed wire, or damaged bypass diode. Contact resistance begins to increase.
2
Arc Formation
At a voltage of 600-1000 V DC, even a micro-break in the circuit causes an electric arc to form with a temperature of 3000-6000°C.
3
Pyrolysis and Ignition
Polymer materials (insulation, PET, PA66) melt rapidly, release flammable gases, and ignite.
Phase 2: Development (1-10 minutes)
1
Class C Module Ignition
The PET film on the back of the module starts to burn, acting like a wick. Drops of burning polymer fall downwards.
2
Roof Covering Ignition
If the module is located less than 10 cm from the roof, the flame easily ignites felt, membrane, or wooden elements.
3
Cascade Effect
The fire spreads to adjacent modules and propagates under the entire installation, creating a chimney effect.
Phase 3: Full Fire (10-30 minutes)
1
Entire Installation Engulfed
The fire engulfs the entire PV system, generating temperatures of 800-1000°C.
2
Hidden Fire
The fire primarily develops under the modules, making it difficult to detect and extinguish.
3
Spread
The fire spreads to the entire roof structure and other building elements.
The sequence above demonstrates why traditional fire detection and suppression systems are ineffective for PV installations. The fire develops too quickly and in hard-to-reach areas.
BifacialMAX System - Fire Risk Elimination
The BifacialMAX System was designed based on a deep analysis of PV fire physics. It introduces five fundamental changes that eliminate the risk of ignition and fire spread.
Five Key Safety Elements

IMPORTANT: Electronic arc fault circuit interrupters (AFCIs) and Rapid Shutdown systems are treated only as an additional layer of safety, not as primary protection. They react after 0.5-1 second, which is when the fire is already developing.
Why it works?
The BifacialMAX System eliminates all three conditions necessary for a fire to occur:
No Fuel
Glass-Glass modules of class A do not sustain fire. Even if an arc occurs, there is no material that could ignite and spread the fire.
Separation
A clearance of ≥15/30 cm from flammable roof elements ensures that even if an arc occurs, its thermal energy dissipates before reaching flammable material.
Localization
Cables in metal conduits and connectors on frames - even in the event of a failure, the fire remains localized and cannot spread.
As a result, even if an electrical fault occurs (which is statistically inevitable over a 30-year period), it does not lead to a fire. The system remains safe throughout its entire service life.
BifacialMAX System Components
Glass-Glass Modules
Exclusively Glass-Glass modules, fire class A according to IEC 61730. No PET film, which is the primary fire carrier.
Safe Distance
Minimum 15