Rooftop Ventilator Hybrid Energy Harvester

Description

Rooftop Ventilator Hybrid Energy Harvester Converting Building Ventilation into Renewable Power This project converts a rooftop ventilator (industrial/Household) into a small renewable power generator by integrating an axial-flux permanent magnet generator with a solar panel system. The ventilator rotates naturally due to wind flow and thermal convection inside buildings. By attaching a pancake axial-flux generator to the ventilator shaft, this rotational motion is converted into electrical energy. The generated wind energy is combined with rooftop solar panels, stored in a 12V battery system, and used to power small loads such as LEDs, phone chargers, and fans. The system demonstrates a low-cost retrofit solution that can transform millions of existing rooftop ventilators into distributed renewable energy generators.

Details

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.

Files

Project presentation.pptx

this is presentation doc give you high-level idea of project work

presentation - 3.66 MB - 03/13/2026 at 18:06

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Project report.docx

This is project report it have detailed documentation of the project. with pictures and formulas and details of components and making steps

document - 2.74 MB - 03/13/2026 at 18:06

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MAJOR_PROJECT.ino

this file is to put in arduino so that it will show the readings live

ino - 3.12 kB - 03/13/2026 at 17:48

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Components

1 × Rooftop Ventilator Acts as the mechanical driver for the generator using natural airflow.

1 × Neodymium Magnets (N52) High-strength magnets used on the generator rotor to create a changing magnetic field.

1 × Copper Wire Coils Used in the stator to generate electricity when magnets rotate past them.

1 × Bridge Rectifier Converts the generator’s AC output into DC.

1 × Filtering Capacitor Smooths the DC output from the rectifier.

Project Logs

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Prototype making plan

varunsontakke80 • 03/13/2026 at 18:24 • 0 comments

Initial Idea

The project started with a simple observation: rooftop ventilators rotate continuously on many buildings. Instead of letting that motion go unused, I wanted to see if it could be converted into electrical energy.

Generator Design

An axial-flux generator was selected because it is compact and works well at lower rotational speeds. Magnets were mounted on a rotor plate and coils were wound to form the stator.

Ventilator Integration

The generator was aligned with the ventilator shaft so that the rotation of the ventilator directly drives the generator.

Hybrid Energy System

To improve reliability, solar panels were added to the system. This ensures power generation even when wind speed is low.

Monitoring System Development

An Arduino monitoring system was created to measure voltage, current, RPM, and temperature. These values are displayed on an LCD.

System Testing

The system was installed and tested under natural environmental conditions. Measurements were taken to evaluate voltage output, current generation, and overall performance.

Build Instructions

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Step 1 – Preparing the Ventilator

A rooftop ventilator was selected and inspected to ensure smooth rotation. The central shaft was prepared to mount the generator rotor.

Specifications:

Technical Specifications	Considered
Outer Diameter	810 mm
Neck Diameter	610 mm
Blade Thickness	0.5 mm
Number of blades	42
Type of blades	Aluminum
Approximate Weight	6.5 kg
Center assembly	MS Galvanized

Step 2 – Building the Generator Rotor

Neodymium magnets were mounted on a circular rotor plate with alternating polarity. Proper spacing was maintained between magnets.

A permanent magnet generator is a generator where the excitation field is provided by a permanent magnet instead of a coil.

Here the rotor Of our generator is a Permanent magnet type rotor which consists of 4 neodium magnets (one of the strongest magnet) whose grade is N52 . Magnets are placed 90 degree with each other.

Specifications:

Technical Specifications	Considered
Number of magnets in each Disc	6
Length of each magnet	5 cm
Breadth of each magnet	1.5 cm
Height of each magnet	1.25 cm
Strength of each magnet	2.5 Wb
Material Of disc	Mild Steel
Diameter	20cm

Step 3 – Winding the Stator Coils

Copper wire was wound into multiple coils. Each coil contained approximately 230 turns. The coils were fixed onto a stator plate.

Wire gauge is a measurement of how large a wire is, either in diameter or cross sectional area. This determines the amount of electric current a wire can safely carry, as well as its electrical resistance .

We have used 26gauge of winding wire in our project which induces

Technical Specifications	Considered
Diameter	20cm
Material	Wood
Type of Winding	Distributed
Conductor Material	Copper (Cu)
Resistance of winding	30 ohms
Phases	Single Phase
Gauge Of conductor	26 swg

Stator is a static part of generator the armature winding of a Generator is almost invariably on the stator. The field winding is usually on the rotor and excited by dc current, or permanent magnets.

No: of Turns= 230

Number of coils= 6

Coil span= 5cm

DISTRIBUTED WINDING: As name suggest, all conductor are distributed in one slot under a pole. If no. of slot is more than no. of pole. Means, winding is distributed in many slot under a pole.

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Rooftop Ventilator Hybrid Energy Harvester

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