By Dr. S. Sakthivel, Technology Group, TATA Consulting Engineers Limited, Mumbai, India
Hot-spot is a phenomenon that is known to occur in photovoltaic (PV) cell under fault conditions such as partial shading, material imperfection, fabrication flaws or damages to the PV cell itself. This study focuses on partial shading, which is a specific fault condition that occurs in PV cells due to dust or shadow, leading to improper illumination distribution over the surface of the PV cell. When the faulty PV cell operating current exceeds the reduced short circuit current, it shall not produce energy, rather start to consume power from the other PV cells connected in series creating hot-spot over the surface. The PV power supply units are applied in remote unmanned hydrocarbon facilities where grid utility power is not available within vicinity. The aim of the present research focuses on evaluating fire hazard of applying PV modules in hydrocarbon field, wherein surface temperature above 85 oC and 230 oC is considered as source of ignition for vapour and dust layer respectively. The present work investigated the impact of partial and complete shading on poly and monocrystalline PV module, with and without presence of bypass diodes. The effects of partial shading on the electrical characteristics of PV modules are investigated. Hot-spot is observed on the front and rear surface of the faulty PV cell with high temperature rise. The results shows that hot-spot point temperature reached to 347 oC, which is a potential source of ignition in a hydrocarbon field.