Solar Nodes & Power

The remote solar routers carry the mesh across the country. A good build and light broadcasting keep them running through winter.

Building a solar node

• Board: low power, such as a Heltec T114, Seeed XIAO nRF or RAK. Avoid ESP32 boards.
• Panel: 6 W or more, monocrystalline. A sealed 18 V panel with an MPPT controller copes better with grey days than a 5 V USB panel.
• Charge controller: a CN3791 based MPPT module, about £6.
• Battery: about 6600 mAh for a garden node, enough for 10 to 12 dark winter days. Double it for a router.
• Battery safety: identical cells only, and a fuse on each cell.
• Enclosure: IP65 or better, cable gland underneath, antenna on top, base sealed.
• Siting: high, clear view south, panel tilted 25 to 30 degrees.
• Admin: turn on remote administration so you can change settings over the mesh.

Full parts list and detail: A beginners guide to building solar nodes by Jppx.

Winter power saving

In winter the routers run short of power, and the mesh carries several times the traffic it used to. Every fixed node can help by broadcasting less:

• Node Info: every 4 to 6 hours.
• Position: every 4 to 6 hours.
• Device and power telemetry: every 4 to 6 hours.

On Android: Radio Config, then Device (Node Info), Position, and Telemetry. Save each page.

From Solar Router Power Conservation by Jppx.