Remote radios and telemetry boxes are a good match for solar because the loads are modest. The catch is that they run all day, every day, often at a site you do not want to visit in bad weather.
A reliable design therefore starts with the boring questions: What does the radio really draw? What happens when the cellular modem is transmitting hard? What voltage does the equipment actually accept? And how many cloudy days should the battery cover?
1. A 24V battery bus can work well—when the equipment supports it
Many outdoor WISP radios use 24V passive PoE, while other products use IEEE-standard PoE or a direct DC input. Those methods are not interchangeable.
For example, Ubiquiti lists the NanoBeam 5AC Gen2 with a 20–27V DC supported range and 8.5W maximum power consumption. That is a useful concrete example, not a rule for every outdoor radio.
[PV array] → [MPPT] → [Battery]
│
├─ regulated/passive PoE → radio
└─ regulated DC supply → LTE/5G routerThe regulators, fuses, and disconnects should be selected around the actual battery range and device requirements.
2. Build a power budget from real operating states
Teltonika’s published RUTX50 measurements illustrate why “router wattage” is not one fixed number. Its documented tests are around 5W in light connected use, while a heavily loaded configuration with multiple interfaces and a USB device can rise into the mid-teens.
For a worked planning case:
| Load | Planning value | Basis |
|---|---|---|
| NanoBeam-class bridge | 8.5W | Published maximum for the example radio |
| LTE/5G router | 6W | Illustrative connected-use planning value |
| Telemetry sensors | 1.5W | Assumption |
| Charge/controller overhead | 0.8W | Assumption |
| Continuous total | 16.8W | Before design margin |
Add a margin for conversion loss, cold-weather effects, traffic bursts, and future accessories rather than pretending 403Wh is exact. A 20% planning margin would put this example near 484Wh/day.
If the cellular modem regularly operates near its maximum-power condition, replace the 6W assumption with the measured or published value for that workload.
3. Size autonomy around access and consequence
At 484Wh/day, a five-day usable-energy target would be:
Five days is not a universal recommendation. A roadside enclosure with easy access may justify less. A mountain relay that needs a snowmobile visit may justify more, or may need a second power source.
PV sizing should use the site’s difficult season, not an annual-average sun-hours number. The array also needs enough surplus to recharge the battery after a poor-weather run while still carrying the live load.
4. Surge and lightning protection need a system view
An Ethernet surge protector can be useful, but it is only one part of the path.
For exposed masts and towers, follow the equipment manufacturer’s grounding instructions and the applicable electrical/lightning-protection rules for mast bonding, cable-entry protection, grounding-electrode integration, conductor routing, DC power surge protection, and Ethernet/coax surge protection.
Avoid copying a fixed ground-rod length, conductor size, or bend radius from a generic article. Those details depend on the structure, jurisdiction, soil, grounding system, and equipment.
The practical goal is to keep power, data, enclosure, and mast protection coordinated rather than adding isolated arrestors with no intentional bonding path.
Calculate the final station runtime with our Battery Runtime Calculator.
Once the networking equipment and daily energy budget are known, explore how they fit into the rest of an off-grid site with the Build My Off-Grid System planner. Its remote preset is illustrative; replace it with your own measured loads. This is an energy-planning model, not a PoE, surge-protection or electrical-compliance check.