Solar Day Lamp With Battery Backup

The Solar Day Lamp With Battery Backup operates as a standalone energy management system designed to harness, store, and utilize solar power efficiently. At its core, the circuit uses two 10W photovoltaic panels (PV1, PV2) to generate electrical energy from sunlight. This harvested energy is routed to charge a bank of three 12V 7Ah batteries (BATT.1-BATT.3), providing a robust energy storage reserve that captures unutilized power during weekends or periods of low usage. When illumination is required, the stored energy drives three white LED arrays (LED1-LED33). Control and switching within the circuit are managed by a network of discrete semiconductor components. Two P-channel MOSFETs (IRF9540, labeled IRF1 and IRF2) act as high-side power switches to regulate current flow from the supply sources to the load. Additionally, a complementary arrangement of bipolar junction transistors—specifically one BC556 PNP transistor (T1) and three BC546 NPN transistors (T2-T4)—forms the analog control logic. This transistor network monitors voltage thresholds and coordinates switching behavior. A 1-kilo-ohm potentiometer (VR1) allows manual calibration or sensitivity adjustment within the control stage, while two DPDT switches (S1, S2) enable user control over routing and operational modes. Various supporting resistors and capacitors are integrated throughout the discrete analog layout to stabilize bias points, filter noise, and ensure reliable switching performance without the need for programmable microcontrollers.