Low-power design · Updated October 2026
How a solar camera cuts roof heat cable energy use
Roof heat cables stop ice dams but usually run all winter. This is how a battery-and-solar camera we built tells them when to switch on, and what the client says it saves.
Quick answers
- What is an ice dam? A ridge of ice at the roof edge that traps meltwater, which then backs up under the shingles into the attic. More
- Do roof heat cables need to run all winter? No. The client behind this project estimates the cables can stay off more than 90% of the time when a camera decides. More
- How much can camera control save? By the client's estimate, $100 to $400 a month in energy per property and 500 to 1,000 kg of CO2 a month for an average US home. More
- How does a camera on a roof get power? From a 1-cell LiPo battery that a small solar panel tops up; one charge lasts about six months. More
- How long did the camera take to build? Nine months from the first sketch to the first manufacturing batch, and 9,500 units have shipped. More
- 90%of the time the heat cables can stay off, by the client's estimate
- 6 monthson one battery charge, measured on the shipped camera
- 9 monthsfrom concept sketches to the first manufacturing batch
- 9,500cameras shipped to the client's customers
What is an ice dam and why do roofs need heat cables?
An ice dam is ice that builds up at the edge of a roof. When the softer snow above it melts, the water cannot reach the gutter and runs back under the shingles.
Ice forms at the edge
Snow and ice collect where the roof meets the gutter. The ridge grows into a dam and hangs icicles over the drain.
Meltwater backs up
Snow higher on the roof melts first. The dam stops that water from flowing down the drain, so it pools and pushes up under the shingles.
Water reaches the attic
The water enters the attic. Owners face mould, repair bills and, where it reaches wiring, an electrical hazard.
Roofs in snowy parts of North America are often fitted with heat cables to prevent this. They are electric heating cables laid along the roof edge, and they melt the snow and ice there so a dam cannot form. They protect the building well. Most of them, though, run whenever they are switched on, whether or not there is any ice to melt, and the owner pays for every hour.
How much energy do always-on heat cables waste?
Most of it. The client behind this project estimates the cables could be off more than 90% of the time without putting the roof at risk.
A heat cable left on runs through every dry day and every cold night with a clear roof. The owner pays for all of those hours, and the grid carries the load at the time of year when demand is highest.
Controllers based on a thermometer try to cut this. They switch the cables by air temperature, so they can only guess at the ice from the weather. They never see the roof edge itself.
A camera does see it. With cables switched by what is on the roof, the client estimates savings of $100 to $400 a month in energy, depending on the size of the property, and 500 to 1,000 kg (1,000 to 2,000 lb) of CO2 a month for an average American home. These are the client's figures; we have not measured them ourselves.
How does a camera decide when the heat cables run?
It photographs the roof edge, judges the snow and ice on the board, and the cables switch on only when an ice dam is starting to form.
Which heat cable control uses the least energy?
The one that checks the roof. Each option below switches the same cables; what changes is what the switch knows.
| Control | What it checks | When the cables run |
|---|---|---|
| Always on | Nothing | All winter, ice or not |
| Thermometer or weather controller | Air temperature and the forecast | Whenever the weather suggests ice might form |
| Camera with detection | Snow and ice at the roof edge, plus weather data | Only when ice is building; the client estimates off more than 90% of the time |
In the system we worked on, most of the detection runs on the camera itself: the ESP32-S3 on the board judges the snow and ice, and only the result goes through a hub on the property to the cloud. The camera can also send the picture for the cloud to check. The cloud combines the result with weather data, so the cables switch on early enough and off again as soon as the edge is clear.
How does a camera on a roof run without wiring?
It sleeps almost all the time and lives on a battery that a small solar panel tops up. There is no mains power at a roof edge, so a wired camera was never an option.
The camera is a variant of our Tokay Lite board: an ESP32-S3 with an OV2640 image sensor, a PIR motion sensor, infrared LEDs for night pictures and an external real-time clock. In standby the clock switches the main regulator off, so the board draws microamps. The clock timer or the motion sensor wakes it to take a picture and send it over Wi-Fi, and then it goes back to sleep.
The solar panel in the lid charges a 1-cell LiPo in daylight. The camera is often buried in snow for weeks, so the battery has to carry it alone. Measured on the shipped camera, one charge lasts about six months, which covers a northern winter.
Comparing boards for a battery camera of your own? Our ESP32-CAM vs Tokay Lite page sets the two side by side.
Cold and sun
The camera stays on the roof all year, so it has to work through −40 °C winters and summer sun. The enclosure is UV-resistant Lexan.
Dark and snow
Ice forms after dark, so night pictures were a requirement. Infrared LEDs light the roof edge to about 10 m.
Installers on the roof
The housing is sealed against rain and snow and built to take the weight of a person who steps on it during installation or maintenance.
How long does it take to build a camera like this?
Nine months, from the first concept sketch to the first manufacturing batch. A US roofing-equipment company brought us the problem; we designed the camera and the hub that links the cameras on a property to the cloud.
The time was short because the electronics started from a board we already had. The early months went into the enclosure, solar charging and the power budget rather than a new board from zero. We then supervised the manufacturing ramp-up for the first year before handing production to the client.
The client has shipped 9,500 cameras to homes and facilities across the United States, and puts its saving against the alternative it had priced at about $300,000. The full case study is on our solar roof camera page.
Where this applies at Maxlab
The roof camera runs on the same design as Tokay Lite, our open-source ESP32-S3 camera board. The schematic and layout are on GitHub under CERN-OHL-P-2.0 and the SDK under Apache 2.0, and single boards are sold through Mouser. You can test the wake cycle, the infrared and the power draw on a board before committing to a custom device.
If your product has to run for months on a battery somewhere without power, the work page shows the devices we have taken to production, and our hardware and firmware services cover the power budget, enclosure, firmware and the handover to the factory.
- Platform
- Tokay Lite, ESP32-S3, OV2640
- Power
- 1-cell LiPo plus solar, about 6 months per charge
- Concept to first batch
- 9 months
- Units shipped
- 9,500
Building a device that has to last a winter on a battery?
Tell us where it will sit, what it has to see or measure and how long it must run between charges. We reply within 24 hours.
Or email [email protected] or book a 30-minute call.
Common questions
Do roof heat cables use a lot of electricity?
They can, because most run whenever they are switched on, ice or not. The client behind our roof camera estimates that switching the cables by what a camera sees saves $100 to $400 a month in energy per property, depending on its size.
Can roof heat cables run only when there is ice?
Yes, if something decides for them. A thermometer or weather controller switches them by air temperature and the forecast. A camera-based system looks at the roof edge itself and switches the cables on only when an ice dam is starting to form.
What is an energy-efficient vision system?
A camera built to spend almost all its time asleep. Ours draws microamps in standby, wakes on a real-time clock timer or a motion sensor, takes a picture, sends it over Wi-Fi and switches off again. The roof camera in this article runs about six months on one battery charge.
Is there a solar-powered ice dam melter?
Heat cables draw too much power for a small solar panel, so they stay on mains power. What runs on solar in this system is the camera that tells the cables when to switch on: a small panel in its lid tops up a 1-cell LiPo battery.
How do you monitor snow and ice on a roof remotely?
Mount a camera at the roof edge that can judge what it sees. In the system described here, the camera runs most of the detection on its own board and a hub on the property passes the result over Wi-Fi to the cloud, which adds weather data. The camera can also send the picture for checking in the cloud.
Does a roof camera work at night or under snow?
At night, yes: infrared LEDs light the roof edge to about 10 m. Under snow the camera cannot see, but the battery keeps it running for weeks until the panel and lens clear, about six months on one charge.
How many cameras does a roof need?
One camera covers a small roof. Larger roofs get several, placed so that every stretch of heat cable is in view of one of them.
How cold can the roof camera get?
It is built for −40 °C winters and stays on the roof through the summer, in a UV-resistant Lexan enclosure sealed against rain and snow.
Can Maxlab build a similar camera for our product?
Yes. The roof camera started from our Tokay Lite board and went from concept sketches to the first manufacturing batch in nine months. See our hardware and firmware services or tell us about your project.
