The short answer
It depends on the model, and it is worth settling before you order. A mains-wired electric rooflight with no backup simply stays where it was when the supply failed, open or closed. Some units carry a battery backup that completes a movement, and many have a manual override, such as a hand crank or release. The manufacturer's guidance for the exact model is the final word.
The three things a unit can do when power stops
Electric rooflights fall into three groups when the supply fails. The first stays exactly where it is. With no power, the actuator has nothing to move it, so a lid that was closed remains closed and a lid that was open remains open. The second has a backup battery in the control box, which can finish a movement or close the unit. The third offers a manual override, a way to move the lid by hand.
These are not mutually exclusive. A unit might hold its position and also give you a hand-operated release. What matters is knowing which your chosen model does, because the behaviour differs between manufacturers and between product lines from the same manufacturer. We only state what the maker's own documents say, and we do not describe a model's backup from memory.
| Type | Behaviour in a power cut |
|---|---|
| No backup | Lid stays in its last position |
| Battery backup | Control box may finish or close the movement |
| Manual override | Lid can be moved by hand using a crank or release |
| Solar unit | Runs from its own battery, not the house supply |
Why a unit left open matters
The case people worry about is a rooflight left open when the power goes. A rain sensor normally closes the unit when it detects wet, but that closing needs power. If the supply fails while the lid is up, the sensor cannot act, and the lid stays up until power returns or someone moves it by hand.
That is the situation a manual override or battery backup is there to cover. Where a unit sits over a kitchen island or a bedroom, the ability to close it by hand is worth having. Where it sits over a lightly used landing, the risk is smaller. Our guide to rain sensors describes how the sensor and control box cooperate, and why the sensor leans on the same supply as the motor. It is a sensible thing to weigh when choosing where the unit goes, for example over a hallway rather than a bed.
Manual override in practice
A manual override takes different forms. Some units have a removable crank that engages with the drive, so you can wind the lid open or closed. Others have a release that disconnects the actuator, letting the lid be moved by hand or lowered under its own weight. Reaching it may need steps if the unit is above head height, which is a practical point to settle at the survey.
Where the override sits matters as much as whether there is one. A crank point that is hidden behind a fixed shelf or a stair is no use in practice. We ask where the override is on the chosen model, check that it can be reached from the room, and record the position in the job plan.
Because overrides vary, we do not promise that every unit has one. We tell you what the manufacturer lists for the model you are considering.
Whoever lives in the house should be able to act on the answer. Keep the maker's instructions for the power-cut case somewhere easy to find, such as with the boiler manual, and tell anyone who might be home alone with the unit, because a manual release only helps if the person standing under it knows it exists. At handover we go through the release with you in the room and write down where it sits.
- Does the model have a manual crank or release?
- Where is it, and can you reach it from the floor?
- Is a tool or key needed to use it?
- Does it affect the rain sensor or the guarantee?
Questions to ask before ordering
Because the behaviour is model-specific, the best time to find out is before the unit is ordered. Ask the manufacturer's documents, or ask us to read them with you, and put the answers in writing.
A list of questions helps. Does the unit hold its position without power? Is there a battery backup, and what does it do? Can it be opened or closed by hand, and how? What happens when the power returns, and does the unit need resetting? These all have definite answers in the product's technical sheet.
- Does the unit hold its last position without power?
- Is there a battery backup, and what will it do?
- Can the lid be moved by hand, and how?
- Does the unit reset itself when power returns?
Solar units and the supply question
A solar rooflight is the exception to the usual worry, because it does not rely on the house supply. Its battery is charged by its own panel, so a cut in mains power does not stop it. Its limits are different: a flat battery after a run of dull days. Our answer on solar powered skylights in winter covers that side.
For a mains-wired unit, the cable and control box are covered in the answer on electric rooflight wiring, which also explains who connects the supply and what is certified.
How it is noted at handover
By the fitting day the plan Ridgeway Skylights wrote for your job has already named the unit, and the handover covers how it behaves without power. We show you where any override is, how to use it, and where the maker's instructions are kept. The plan records what the manufacturer states for that model, so you are not relying on memory later.
We also test the unit with you present: open, close, and the sensor response, so you see the controls work before we leave. If the model has a battery backup, the handover notes where the battery sits and what the maker says about its life.
Those notes are filed with your 10-year workmanship guarantee and the maker's paperwork. For the full range of drive and control options, the electric opening rooflight installation page sets them out.