Self-powered directional light sensor for solar arrays. 80 phototransistors on a 100mm sphere measure the brightest sky direction via weighted centroid algorithm. ESP32 + 4G MQTT. BOM ~$50.自供电光伏阵列定向光传感器。100mm球体表面80个光电晶体管，通过加权质心算法测量天空最亮方向，4G MQTT传输方向向量。BOM约¥372。