Remote repeaters, wireless internet links and small telecommunications towers are among the most demanding small solar jobs. The load never switches off, the site is usually on an exposed hilltop that is hard to reach, and a power failure often goes unnoticed until communications are needed most. A reliable system is designed around four principles: size for the continuous DC load, allow generous days of autonomy, monitor the site remotely with alarms, and build it so that visits are rare and security is solid.

Continuous DC loads change the maths

Most communications equipment runs on DC, commonly at 12, 24 or 48 V, with 48 V widely used in telecommunications gear. Powering it directly from a DC battery system avoids the conversion losses and idle draw of an inverter, which matters when every watt runs 24 hours a day.

Radios draw more power while transmitting than while listening, so use an average based on realistic transmit time, not just the receive figure. Then add everything else inside the enclosure. The table below is a worked example; the equipment specifications for your site are what count.

A steady 60 W sounds small, yet over a day it uses more energy than an efficient household fridge. Allow a margin for charge controller, cabling and battery losses, and leave room for equipment that is likely to be added later.

Check each device's supply voltage range as well. DC equipment has a minimum and maximum input voltage, and a battery's voltage moves between full charge and its low cut-off. The battery, charge controller and any DC-DC converters must keep the supply inside that window in every condition, from a cold morning at full charge to the end of a long cloudy spell.

Days of autonomy and array sizing

Critical communications sites are commonly designed for five or more days of autonomy, and more where storms or wet tracks can cut access for longer. In the example above, five days means about 7.2 kWh of usable storage before allowing for cold weather and the gradual capacity loss every battery experiences with age.

Points that matter on hilltop sites:

• Size the array for the worst month. It must cover daily use in winter and also recover the battery after a cloudy spell. Hilltops can sit in cloud or fog when the valley below is sunny.
• Oversize the array rather than the risk. Extra panel capacity is modest in cost compared with repeated site visits or an outage.
• Manage battery temperature. LFP batteries should not be charged below freezing without built-in protection or heating, and high enclosure temperatures shorten any battery's life. A shaded, insulated and ventilated enclosure helps with both.
• Consider generator support only where needed. Larger sites sometimes add a generator that starts automatically at a low state of charge, but that brings fuel deliveries and servicing to a site you want to visit rarely. The generator vs battery guide sets out the trade-off.

The step-by-step method in the off-grid sizing guide applies here too, with the difference that the load profile is flat around the clock.

Monitoring and alarms

At a remote site, monitoring is what turns a surprise failure into a scheduled visit. Useful measurements include:

• Battery voltage and state of charge, especially the early-morning low point.
• Solar charge current, which shows soiling, shading or a failed panel.
• Load current, which reveals faulty or newly added equipment.
• Enclosure temperature and door-open status.
• Low-voltage disconnect events and generator status if one is fitted.

Data can travel over the site's own communications link, a mobile data modem where there is coverage, or a satellite connection for the most remote locations. Alarms should reach at least two responsible people. Load priority is worth designing in as well: when the battery runs low, the system can disconnect secondary equipment first so the primary repeater stays on air longer. Watching trends helps too, because a morning state of charge that slowly declines over several weeks usually points to growing shade, dirty panels or an ageing battery well before the site fails.

Security and physical protection

• Lock it down. Use lockable steel enclosures, tamper-resistant fasteners on panel mounts and a fenced compound.
• Plan for lightning. Exposed hilltops attract strikes. Earthing and surge protection on DC circuits and antenna feed lines should be designed and installed by qualified professionals.
• Engineer for wind. Ridge-top mounts face stronger winds than sheltered sites and should be rated for the wind region and exposure.
• Keep stock and vermin out. A stock-proof fence protects mounts, and conduit protects cables from rodents.
• Manage fire risk. Keep vegetation cleared around the compound and mount equipment on a non-combustible base.
• Keep records off site. Store equipment lists, serial numbers and photos away from the site so theft or damage can be documented quickly.

Designing for difficult access

1. Document the route. Record the track, gates, key holders, wet-weather limits and GPS coordinates, and confirm access permissions if the site is on someone else's land.
2. Reduce the need to visit. LFP batteries need no watering, and a generous array with remote monitoring means most checks happen from a screen.
3. Standardise and label. Use common battery modules, keep a wiring diagram inside the enclosure and label every circuit.
4. Schedule inspections before winter. Plan at least an annual visit to check terminals, earthing, seals and panels. The battery maintenance guide covers what to look for.
5. Keep working at heights professional. Never climb a tower or mast without the right training and equipment. Antenna and tower work belongs with qualified specialists.

Next steps

If you manage a repeater, wireless link or telemetry site that needs dependable power, request a free assessment from Blue Energy Solar. The Remote Telecommunications Solar service, a DC power system with days of autonomy for repeaters, radio, internet and monitoring equipment, starts from $6,990 per site on the energy market. Prices are indicative and are confirmed after a site assessment.

Frequently asked questions

Can a repeater share power with a nearby shed or homestead system?

It can if the site is close, but a household or shed battery can be drained by everyday use, leaving the communications equipment exposed. A dedicated DC system, or at minimum a reserved battery capacity with priority for the communications load, is usually more dependable. Any connection between systems should be designed by an accredited installer so a fault in one does not take down the other.

Why choose 48 V rather than 12 V for a remote site?

For the same power, a 48 V system carries a quarter of the current of a 12 V system. Lower current means less voltage drop along cables to the top of a mast or across a compound, smaller conductors and lower losses. Much telecommunications equipment is built for 48 V, while very small single-radio sites can still work well at 12 or 24 V.

How often do batteries at a remote site need replacing?

It depends on chemistry, enclosure temperature and how deeply the battery cycles each night. LFP batteries are commonly warranted for 10 years, while lead-acid batteries in hot enclosures often need replacing much sooner. Rather than relying on age alone, compare monitoring data over time; falling morning state of charge on sunny days is a sign that capacity is fading and replacement should be planned.