In the recent years, solar photovoltaic (PV) industry is very popular. PV systems are installed more and more. Therefore, the systems need to detect and maintain their performance with finding problems by related instruments. The problems causing low power generation efficiency could be performance decay or degradation due to outmoded system, PV module cracks or hot spot effect and so on. The study helps on-site maintenance and detection technicians to analyze and resolve problems by I-V performance analyses, thermal infrared imager and electroluminescence imager in order to keep system having highest efficiency operation and reach the goal of power generation effectiveness optimization.