Reliability of photovoltaic systems for telecommunication applications

Abstract

Solar photovoltaic systems have achieved grid parity in many countries, and several targets have been set to reach 100% renewable energy systems by 2050. Solar Photovoltaic (PV) is a progressively widespread and efficient way to generate electrical energy for different applications, including telecommunications systems. Telecommunications is one of the critical industries with massive power requirements, where the reliability of power generation equipment is a critical issue. The Field experience revealed that the main contributor to the maximum power degradation of crystalline silicon PV modules is the short circuit current decrease. Hot and humid climate zones are the most affected by this degradation. The degradation mechanism highly associated with short circuit current reduction of PV modules is encapsulant discoloration, which is mostly caused by UV light, temperature, and humidity. In this thesis, the impact of PV module positioning (tilt and orientation) on the PV module degradation, mainly encapsulant browning, is carried out. For this purpose, the activation energy for encapsulant browning is calculated in the Algeria region using the acceleration factor modeling approach for climate-specific degradation. The model is applied based on the modified–Peck's degradation model and the hourly meteorological data and field degradation data from two locations, Algiers (temperate climate) and Adrar (hot/dry weather), are used for this analysis, where the same PV module type is fielded for 9-10 years in these locations. Then, the activation energy obtained is used to find the degradation rate of encapsulant browning for different PV module positioning angles in Algiers. After that, the tradeoff between energy i

yield, PV module lifetime, and yearly energy production is evaluated for each positioning case. From another perspective, field experience for 5 years in a large utility-scale PV generation plant revealed that power electronic components are responsible for 37% of unscheduled maintenance in the PV system and 59 % of the related cost. Most power converters, including DC-DC converters and DC-AC converters, use Insulated Gate Bipolar Transistors (IGBTs) as switching devices, and IGBTs are among the weakest components in a PV inverter. The reliability of power electronic devices in a PV inverter is usually affected by external conditions, mainly solar irradiance and ambient temperature, which are referred to as the mission profile of the system. In this thesis, the impact of the PV module positioning (tilt, orientation) on the PV inverter lifetime is studied using mission profile-based lifetime estimation of power devices. The evaluation is based on the mission profile of Algiers, Algeria, where the irradiance values are obtained for various tilt and orientation angles. After that, the tradeoff between the PV energy yield and the inverter lifetime is analyzed for different PV array positioning