Modern buildings already have rooftop ventilators that spin all day due to wind and hot air rising from inside the building. Normally this motion is wasted. In this project, I explored a simple idea: can this rotation be used to generate electricity?

The result is a hybrid renewable energy system where a rooftop ventilator is modified to drive a small axial-flux permanent magnet generator. When the ventilator spins, magnets on the rotor pass over copper coils in the stator and produce electrical energy. The generated AC power is rectified into DC and used to charge a battery.

To improve reliability and ensure energy generation even when wind is low, the system also includes solar panels connected through a charge controller. Both wind and solar sources feed a 12V battery system, which can power small loads such as lighting, phone chargers, and fans.

An Arduino-based monitoring system measures voltage, current, RPM, and temperature. These parameters are displayed on a 16×2 LCD so the performance of the system can be observed in real time.

The goal of this project is not just to build a generator, but to demonstrate a practical retrofit solution. Rooftop ventilators already exist on many factories, warehouses, and residential buildings. If these ventilators can also produce electricity, they could become a simple distributed renewable energy source without installing large wind turbines.

The project focuses on:

• Low cost hardware

• Reuse of existing infrastructure

• Simple construction methods

• Hybrid renewable energy generation

This prototype shows that even small sources of mechanical motion on buildings can be used to produce useful electrical power.