LoRa Sensor Node — Solar Harvesting and 15 kV Line Sensing
Description
A battery-and-solar powered remote monitoring node for electric fence lines. It sits outdoors with no mains power and no network, and must report line condition over long range for years without a site visit.
Stack
- SX1262 sub-GHz LoRa transceiver
- STM32L052 ultra-low-power microcontroller
- 2S LiFePO4 battery pack with MPPT solar charging
- High-voltage sensing front-end rated for 12–15 kV line pulses
The Hard Part
15 kV on the same board as a microcontroller. Electric fence energisers produce high-voltage pulses by design. The sensing front-end has to survive and measure them while the digital side, millimetres away, sees nothing. Isolation, spacing, and clamp strategy set the board outline before any routing.
Power budget over seasons, not hours. The node has to carry itself through low-light weeks on stored charge. MPPT harvesting, LiFePO4 chemistry for cycle life across an outdoor temperature range, and an STM32L0 chosen for sleep current — the radio duty cycle then has to fit what the harvest actually delivers.
Range with a small antenna. LoRa buys link budget, but only if the RF section is laid out to keep it. Matching network, ground plane treatment, and antenna keep-out were resolved at layout.
Deliverables
- Complete bill of materials with sourcing and lifecycle checked
- Schematic and board outline with high-voltage spacing enforced
- Power budget model against expected solar yield
- Fabrication package
Published without client, project name, or location under NDA. Silicon and architecture are unchanged.