Guide · off-grid solar power
Solar-powering remote sensors, so farm monitoring never stops.
A plain guide to running low-power tank and farm sensors on solar out where there is no mains: how small the panel and battery really are, why you size the whole thing around winter, and how the readings keep coming through a week of cloud.
Last updated 4 July 2026 · by Alien IT Solutions
The point of off-grid solar for sensors
The best place for a tank sensor is almost always the worst place for power. Bores, dams and back-paddock tanks sit well away from a shed, a plug or a mains cable, and running power to each one is neither cheap nor sensible. A small solar panel and battery solve that quietly, so each sensor looks after its own power and keeps reporting for years without a wire back to the house.
The good news is that a proper monitoring sensor asks very little. It sleeps, wakes briefly to measure and send, then sleeps again. That tiny appetite is what makes off-grid solar practical, and what sets it apart from the heavier gear on a property that needs a much bigger power budget.
Why the power draw is so small
A tank level sensor is not a hungry device. For all but a few seconds of the day it is asleep, drawing almost nothing. When it wakes, it takes a reading, hands it to the low-power radio, waits for the tiny handshake that confirms it was heard, and sleeps again. That whole cycle happens a handful of times an hour and is over in moments, so the average draw across a full day is very low.
That average is the number that matters for solar. You are not powering a device that runs flat out around the clock, you are topping up a battery that spends most of its life idling. It is why a panel you could hold in one hand is usually plenty, and why the same setup carries the sensor through nights and cloudy days without breaking a sweat.
This is the important distinction from a high-draw job like a long-range radio link, which has to keep a real connection alive and pushes far more power all day. That belongs on its own larger panel and battery. Our sister service Long Range WiFi handles the heavier connectivity, and we keep the light monitoring load on its own modest power so neither one starves the other.
How we size a setup
Three parts working together so the readings never stop.
Start with the daily draw
We work out how much the sensor uses across a full day, sleeping and waking, so everything else is sized to a real number rather than a guess.
Size the battery for days, not hours
The battery is chosen to carry the sensor through several days of poor or no sun and still hold margin, so a run of weather never takes a tank offline.
Size the panel for winter
The panel is matched to the weakest sunlight of the year, not the strongest, so it can refill the battery even in the short grey days of June and July.
Leave headroom on purpose
We build in spare capacity rather than sizing to the edge, so the odd bad week, a dusty panel or an extra sensor later does not tip the setup over.
Why winter is the number that counts
It is tempting to size a solar setup around a bright summer day, because that is when everything looks easy. That is exactly the trap. A panel and battery that sail through January can quietly fall behind in the middle of winter, when the sun is low, the days are short, and a run of grey weather can string several weak days together. If the setup only just coped in good conditions, winter is when a tank goes dark.
So we size it the other way around. We look at the worst realistic winter week for the site, the short days and low sun angle, and make sure the panel can still put back more than the sensor takes out across that week, with the battery holding a reserve on top. Get winter right and summer looks after itself.
Where a site sits matters too. A southern, cooler property with more overcast winter days needs more margin than a bright inland one, and a panel shaded by a ridge or tree in the low winter sun will underperform its rating. We account for the site, not just the sensor.
Riding out a cloudy week
The battery takes over
When the sun disappears for days, the panel gives little, so the battery simply runs the sensor on its own from the reserve we sized in.
The reading keeps coming
Because the daily draw is so small against that reserve, the sensor keeps measuring and sending right through the grey spell, so a tank never quietly drops off the dashboard.
The panel refills the gap
When the sun returns, the panel puts back far more than the sensor uses each day, so the battery climbs back to full over the following days on its own.
Panels, batteries and where they sit
The hardware out in the paddock is deliberately simple and rugged. The panel is sealed and rated for full sun and heat, mounted at an angle that both sheds dust and catches the low winter sun, and placed clear of stock, shade and the odd curious animal. Rain does most of the cleaning, and an occasional wipe after a dusty stretch or a visit from the birds is usually all it ever asks.
The battery is chosen to last for years of daily charging and discharging, and it is sized so it never has to run right down, which is what wears a battery out fastest. When one does eventually need replacing, it is a simple swap on a routine visit, not a callout.
One small solar setup can often carry more than the tank sensor, as long as the extra load is just as light. A nearby trough sensor or a gate sensor sips power in the same way and can share the same panel and battery. Heavier gear like a camera or a radio link stays on its own power. For non-water sensing on the same dashboard, our sister service Rural IoT covers gates, pumps, frost and more.
Watching the power, not just the water
A sensor is only useful if you can trust it to be awake. That is why the same dashboard that shows your tank levels also keeps an eye on each sensor's battery. If a battery starts trending low, whether from a shaded panel, an unusually long cloudy spell or simple old age, you get a heads-up well before it becomes a problem.
That early warning turns a flat battery from a nasty surprise into a planned job. Instead of driving to a bore to find the sensor went dark days ago, you see the trend on your phone, put a fresh battery on the next trip, and the tank never stops reporting. Monitoring the power is what makes the off-grid promise hold up.
Who builds it
Tank Monitoring is the water-monitoring service of Alien IT Solutions, an Australian IT, networks and connectivity company with more than 18 years of experience. It is part of a family of rural services, all Alien IT: Rural IoT for other sensors, Paddock Networks for whole-property wifi, Long Range WiFi for long links, and Starlink Rural for satellite internet.
Questions people ask
How much solar does a remote tank sensor actually need?
A lot less than most people expect, because a well-built level sensor sleeps between readings and only wakes for a few seconds to measure and send. A small panel, often the size of a paperback, keeps it topped up in most conditions. The panel is not there to run the sensor moment to moment, it is there to refill the battery a little every sunny hour so the battery can carry the sensor through the night and through cloudy days.
Why size the whole thing around winter, not summer?
Because winter is when solar has the least to work with and the sensor still has to run. Southern Australian sites can see a run of short, grey, low-sun days in June and July, so a system that is comfortable in January can quietly fall behind in winter. We size the panel and battery so the worst realistic winter week still leaves charge in reserve, then summer looks after itself.
What happens during a long cloudy spell with no sun?
The battery carries the sensor on its own. We choose a battery big enough to run for several days of poor or no sun and still have margin left, so a week of weather does not take a tank offline. When the sun returns the panel refills the battery over the following days, and because the daily draw is tiny the recovery is quick.
Can one solar setup power more than the tank sensor?
Often yes, for other low-draw sensing on the same spot, such as a nearby trough or a gate sensor, since these sip power in the same way. Higher-draw gear like a long-range radio link or a camera draws far more and needs its own larger panel and battery, so we keep the light monitoring load and the heavy connectivity load on separate power rather than overloading one small setup.
Does the panel need cleaning or servicing out in the paddock?
Very little. The panels are sealed and rated for weather and heat, and rain does most of the cleaning. We angle them to shed dust and catch the low winter sun, and mount them clear of stock and shade. An occasional wipe if a panel gets caked in dust or bird mess is usually the only attention it ever needs.
What if the battery still goes flat one day?
You will know before it does, because the dashboard tracks each sensor's battery and can alert you if one starts trending low, well ahead of any problem. That warning is the point of monitoring the power as well as the water, so a flat battery becomes a planned visit rather than a tank that has quietly gone dark. Batteries are simple to swap and last for years.
Off-grid, and it just keeps reporting.
Tell us the bores, dams and tanks with no power, and Alien IT will size the solar and battery so the readings never stop.
Get a quote