Optimized Solar Grid with Second-Life EV Batteries and Load Control

The global transition toward renewable energy has increased the need for intelligent and resilient power systems that can operate under fluctuating conditions. Solar PV remains widely used but suffers from intermittency, while the rise of electric vehicles has created an opportunity to repurpose second-life EV batteries, which retain usable capacity for stationary storage. Utilizing these batteries enables cost-effective and sustainable hybrid energy solutions. This study presents a hybrid solar microgrid integrating second-life EV batteries with dynamic load prioritization to ensure stable and optimized power flow. The system performs real-time monitoring of solar input, battery state of charge, load types, and grid status to select the optimal operating mode. Unlike conventional systems with fixed switching, this approach uses a structured prioritization algorithm that categorizes loads into critical, essential, and non-essential groups. The architecture includes MPPT, regulated charging, AC-DC conversion, and relay-based load control, managed through microcontroller-based measurement circuits for seamless switching between solar, battery, and grid supply. Through modeling and scenario testing, the system shows improved reliability, reduced grid dependence, and lower energy wastage.