ESP32-Powered Solar Lantern Creates Local Community Message Board

A Solarpunk Vision in Hardware

Solarpunk envisions a future where technology serves communities, powered by renewable energy rather than corporate control. This philosophy inspired maker Victor Frost to build a compact, solar-powered device that looks like a lantern but secretly hosts a local webserver. Jump to the message board feature or explore the technical design below.

Hardware Design and Power

At its core, the device uses an ESP32 microcontroller paired with two 18650 lithium-ion cells. These batteries charge from a small solar panel (presumably 6W as mentioned later). The whole setup is housed in a lantern-like enclosure, blending form and function — it’s both a light source and a digital hub.

Solar Charging and Battery Management

The two 18650 cells ensure the device can operate even without direct sunlight, storing energy for nighttime or cloudy days. The solar panel connects via a charging circuit, making the entire system self-sufficient. This aligns with solarpunk’s emphasis on renewable energy.

A Local Webserver for Community Interaction

The device hosts a simple HTTP server, but it does not connect to the internet. Instead, it creates its own WiFi network. When users connect, they are greeted by a captive portal — similar to public WiFi login pages — which directs them to a community message board.

Captive Portal as a Gateway

By leveraging the ESP32’s captive portal functionality, anyone within a few meters can access the board without needing an internet connection. This design ensures the server remains local and private, perfect for small gatherings, community centers, or events.

Unmoderated, Transparent, and Local

The message board is unmoderated and unfiltered — users can post anything they like. However, physical proximity eliminates true anonymity, as posters are within range of the device. Victor likens it to a digital community corkboard, bringing the solarpunk ethos of trust and local interaction to the 21st century.

Technical Implementation: Firmware and Storage

Under the hood, the ESP32’s flash memory is split into three partitions: one for user data (posts), and two for firmware images. This allows for live updates without downtime, as one partition runs while the other is updated, with a known-good backup for quick rollback if needed.

LittleFS for Data Management

Victor uses LittleFS for the data partition, a lightweight filesystem optimized for flash storage. This enables efficient reading and writing of messages.

UI: A Single String in PROGMEM

An unorthodox choice: the entire user interface — HTML, CSS, and JavaScript — is stored as a single string in the ESP32’s PROGMEM memory, rather than as separate files in the filesystem. This simplifies updates, as firmware and UI are bundled together. It’s a trade-off that may not suit everyone, but it works well for Victor’s single-purpose device.

Open Source and Community Ethos

The project is fully open-source, with code available on GitHub under the GPL license. This reflects the strong overlap between the open-source movement and solarpunk values — sharing, collaboration, and empowerment of local communities.

A Missed Contest but a Successful Project

Victor created this device before Hackaday’s Green Powered Challenge, but it would have been a perfect fit for the photovoltaic category given its 6W solar panel. Yet the maker community welcomes projects of all kinds, and this lantern-inspired message board is a wonderful example of how technology can foster local, solar-powered interactions.

For those inspired to build their own, the source code and design details are readily available. As Victor demonstrates, you don’t need a global network — sometimes the best connections are the ones within arm’s reach.