Solatube is a pipe casing used to channel sunlight from the roof of a building into an enclosed space. The advantage of using Solatube is that it can avoid excess light being directed. However, there is no mechanism for controlling the intensity of sunlight entering the room through the Solatube. By adding control settings, the intensity of incoming sunlight can be adjusted so that it can help visually comfort. It is necessary to control the opening and closing valves to adjust the power of the light produced by the Solatube and the lamp. So, it is needed to design an optimal lighting source to regulate the quantity of light received by the room and the people in the room. The paper aims to achieve good control results by valve controlling using PID control which tunes the parameter by the Genetic Algorithm. Thus, the light intensity entering the room will be stable 24 hours a day. So, that eye comfort, visual coolness and energy savings can be achieved.

A Solatube is a daylight system that used to save electricity generated from nonrenewable energy sources. However, the amount of solar entering the room via the Solatube had not been controlled. The goal of the research is maintaining a more consistent light intensity of 350 Lux for 24 hours. The study attempts to create a lighting optimization system based on an experimental design based on a PID controller. The system consists of a microcontroller, a light sensor, some motors and drivers. The PID parameter is tune beginning with the Ziegler-Nichols method and optimizing it with the Genetic Algorithm (GA) approach. The GA approach produced the best results with a population of 50, a Kp value of 0.105210, a Ki of 0.052901, a Kd of 0.046443, and a tuning time of 94 seconds. The annual savings value of using electrical energy is 22.07%.