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Playlist "Chaos Communication Camp 2023"

Resilient solar energy-autonomous infrastructure with Freifunk-OpenMPPT controllers

Elektra Wagenrad

Freifunk Open-MPPT is an expanding Open-Hardware and Open-Software development project for efficient and resilient energy autonomous infrastructure like communication nodes, environment monitoring, irrigation – and more. The talk presents the currently available models, evolution, scope of current use and presents an outlook of what might follow in the future.

The OpenMPPT development project was initiated by Freifunk in 2017 with the first design handling up to 50 Watt PV (solar) power. The intended application was to build cheap and effective solar WiFi mesh nodes with telemetry. At the time of the project's initiation, there were no small and low-cost solar charge controllers available that included maximum power point tracking. Maximum Power Point Tracking is a technique used in solar power systems to optimize the power output from the solar panels by tracking the point where the panels can deliver the maximum amount of power. The OpenMPPT project aimed to fill this gap and provide an open, cost-effective, and repairable DIY alternative for individuals and development NGOs who look for open hardware and software solutions. Initially, the idea was not to replace or compete with more powerful closed hardware and closed software Maximum Power Point Trackers on the market. However, people and development NGOs kept asking for more power and features like the possibility of adding sensors or building irrigation systems, because they want open hardware and software solutions. The development of the Freifunk-OpenMPPTs is following sue. The newer and expanded FF-ESP32 generations of OpenMPPT controllers are based on the ESP32 MCU by Espressif and can handle up to 400 Watt solar power. They can not only power communication nodes, but also solar powered servers in communities that live off-grid or have unstable power. However, people keep on asking for more power...