oa Hidden Hazards of Applying Photo Voltaic Modules in Hydrocarbon Industry

Background: Solar Photo Voltaic (PV) module based electric power supply systems are being designed for remote unmanned oil and gas facilities where grid utility power is not available within vicinity. PV modules are used in applications such as measurement of process data, telemetry, gas detection, cathodic protection and lighting with voltage levels of 12V, 24V and 48V. Majority of PV modules are made of compounds of semi-conducting materials from Group IV (Silicon and Germanium) and alternatively Group-III/V and Group- II/VI. These materials are in mono crystalline, multi crystalline and in amorphous structure.

Hot spot heating is a phenomenon, occurring in PV module, caused by faulty conditions such as partial shading / material imperfection / fabrication flaws / damages etc. When the faulty PV module/ cell operating current exceeds the short circuit current (Isc), it shall not produce energy, rather starts to consume power from the other PV cells connected in series. Due to the above phenomena localized heating is expected to occur wherein the temperature could rise in the range of 150 – 200 Deg.C.

Built-in bypass diodes are provided in PV modules to prevent localized hotspot; however there are characteristics mismatches between the diode and module which does not prevent hotspot for all faulty cases.

Hot spot test criteria defined in IEC 61215 & IEC 61646 / IEC 61730 / ANSI UL 1703 has inconsistencies hence not harmonized.

Objectives: Application of solar PV module for hydrocarbon facilities may introduce fire hazards due to hotspot phenomena, where minimum ignition energy source of 20 micro Joules (Acetylene) or temperature above 100 Deg.C (Carbon Di-Sulphide) can become the source of ignition. This shall be scientifically studied and specific guidelines and/or standards shall be established based specific materials selection and engineering design.

Methods: Hot Spot phenomena of PV module shall be tested with multiple variables and scenarios such as Module Materials and its structure, Current/ Voltage Level, Irradiation level, Type of shading, Location of Fault in the module.

Results & Conclusions: Solar PV module application in hydrocarbon industry may call for specific material and design requirements to effectively prevent hotspot occurrence in an explosive atmosphere.