Project Hub /IoT & Connected Devices/Predictive Maintenance/Solar Light For A Portable Toilet

Intermediate

ANALOG / DISCRETE

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Solar Light For A Portable Toilet

A self-contained solar-powered lighting system for portable toilets that uses a PIR motion sensor to automatically activate a white LED light when occupancy is detected.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

PIR Motion Detector Sensor Module HC-SR501 Rs. 95.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
2-Slot 18650 Holder with Protective Cover and On/Off Switch – Case Rs. 109.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: 9V Battery + Snap
Voltage Regulator IC (7805 / LM317 / 1117)
Transistors (BC547 / 2N2222 / TIP / MOSFET)
AA / AAA Battery + Holder
Custom PCB / PCB Fab
Enclosure / Box / Case

Browse all components

How It Works

The Solar Light For A Portable Toilet is a completely self-contained, off-grid illumination system designed to provide automated lighting upon occupancy detection. At the heart of the power subsystem is a 9V 450mA polycrystalline solar panel, which absorbs ambient sunlight during the day to generate electrical energy. This harvested energy is conditioned by an LM317 voltage regulator (IC1) to safely charge a 4.8V 1800mAh rechargeable battery pack (BATT.1) without overcharging. A manual power switch (S1) is integrated into the circuit to enable or disable the system entirely when necessary. When the unit is active, it relies on a PIR motion detector module to continuously monitor the interior of the enclosure for infrared thermal signatures indicating human presence. Upon detecting motion, the PIR module outputs a control signal that drives the gate of a BS170 N-channel MOSFET (T1). Acting as an electronic switch, the BS170 allows current to flow from the battery pack through a network of current-limiting resistors (6.8-ohm and 4.7-ohm 1W) to power a high-intensity 1W white LED (LED1). This configuration ensures the light only illuminates when needed, maximizing energy efficiency and preserving battery reserve during periods of prolonged disuse.

Why Build This

Design and deploy robust off-grid power management systems using solar harvesting and linear voltage regulation for remote infrastructure.

Integrate digital sensor modules with discrete analog switching stages to optimize energy efficiency in battery-powered embedded applications.

Apply thermal and electrical load calculations using power resistors and MOSFET switches to safely drive high-output solid-state lighting.

Real-World Application

Providing automatic, off-grid lighting for portable toilets at construction sites, farms, campsites, and street-sides.

Skills You'll Learn

Solar power harvesting

Linear voltage regulation

Passive infrared (PIR) sensor integration

MOSFET electronic switching

Battery charging circuit design

Power dissipation management

Safety Precautions

Ensure correct polarity when connecting the rechargeable battery pack and solar panel to avoid circuit damage.

Technology Tags

SOLAR PANEL

PIR MOTION SENSOR

LM317 VOLTAGE REGULATOR

BS170 MOSFET

WHITE LED

RECHARGEABLE BATTERY

PCB

Frequently Asked Questions

Why is an LM317 voltage regulator used in this circuit?

The LM317 (IC1) steps down and regulates the voltage coming from the 9V solar panel to a safe, controlled level suitable for charging the 4.8V rechargeable battery pack without damaging the cells.

What is the function of the BS170 MOSFET in this design?

The BS170 (T1) acts as a low-resistance electronic switch. When the PIR motion sensor detects movement, it signals the MOSFET to turn on, completing the circuit from the battery to the 1W white LED.

Can I leave the solar light running continuously instead of using the motion sensor?

Continuous operation is not recommended because the 1800mAh battery pack is sized for intermittent, motion-triggered use; running the 1W LED constantly would quickly deplete the stored energy before the solar panel could recharge it.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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