The integration of renewable energy for electricity generation has become imperative to meet environmental goals and curb global warming. Photovoltaic energy is one of the technologies with the highest potential and growth prospects. In photovoltaic power plants, periodic inspection techniques for the modules may be necessary. Among various inspection techniques, electroluminescence and photoluminescence imaging are of significant interest as they provide information about module performance and detect various types of failures. This article presents a technique named passive electroluminescence and photoluminescence that enables luminescence acquisition during daylight conditions while the photovoltaic power plant is in normal operation. The technique is based on an electronic board that is connected within the photovoltaic string and modulates the signal. A lock-in approach is also implemented, which involves obtaining several pictures under low and high emission states, which are then processed to remove the background signal generated by sunlight. The study focuses on two lock-in approaches: synchronous and asynchronous, which differ in whether the camera and the electronic board are coordinated. Both approaches have been successfully implemented, yielding similar results.