Are Solar-Powered Opening Rooflights Any Good?

A solar-powered rooflight, sometimes called a solar skylight, has three extra parts compared with an ordinary manual unit. A small photovoltaic panel collects daylight and turns it into electricity. A rechargeable battery stores that charge. A motor, usually built into the frame, moves the sash when you press a button on a remote or wall-mounted control.

The panel is small, because the job is small. Opening and closing a sash uses very little energy, much less than powering a light. On a bright day, the panel tops the battery up, and on a dull day the battery carries the unit through. For most units, the panel is part of the product, either on the frame or on a short lead nearby, and it sits on the outside of the roof.

The big attraction is simple: no mains cable. A unit can be put in a roof where power is far away, and the room below needs no chasing, no new circuit and no electrician for the supply. Some people find that appealing for a home that has already been decorated.

Think of the places where bringing mains power to the roof would be a nuisance. A finished loft bedroom with a new ceiling. A landing in a house that has just been redecorated. A detached garage or outbuilding with no supply nearby. A flat-roofed extension at the end of a garden. In each case, a solar-powered unit offers a way to have an opening rooflight without running a mains cable through the house.

It also suits a replacement. If you are swapping an old manual rooflight or roof window for one that opens by remote, the solar version saves the work of running cable to a spot where none exists. Swapping a unit for its equivalent is controlled work under Part L, which means the new one meets the thermal limit for its kind. We send the notification when the job calls for it.

The roof matters too. A panel needs daylight, not necessarily sun, but a roof shaded all day by a taller building or a large tree will keep it short of charge. A south or west facing roof slope gets the most light, and a north facing one still works, but with less to spare.

A solar unit is a good product with a clear boundary. If the battery runs low after a long dark spell, the motor will slow or stop until it has recharged. Winter in the East Midlands has plenty of grey days, and a unit that is opened and closed often will draw more from the battery than one that moves a few times a week.

Battery life also needs thought. A rechargeable battery wears over time and will eventually need replacing. How long that takes depends on the type, the use and the temperature, so the manufacturer's instructions are the place to look. It is wise to ask where the battery sits and how it is reached before you buy.

The panel can also collect dirt. A film of dust or leaves on its surface cuts its output. A light wipe from time to time keeps it working.

Finally, accessories vary. A mains system can often accept a rain sensor, a wind sensor, a timer and a smart link. Solar units may offer fewer of these, though a rain sensor is common on many. Check the specification of the chosen model against what you want the unit to do. The sensors and controls guide lists the options to think about.

Start with the room and the spot. Where do you stand when you want fresh air, and how often will the rooflight need to move? A bathroom unit opened several times a day behaves differently from a landing unit opened at weekends.

Then look at the route for power. If a cable can be run neatly while the work is open, mains power is steady and flexible. If it cannot, solar is a very sensible answer. What mains wiring involves is set out in the electrician answer, so the two can be compared honestly.

Then think about a power cut. A mains unit stops moving if the supply fails unless it has a backup, while a solar unit carries on as long as its battery has charge. That is a real point in favour of solar, and the fuller story is in the power cut answer.

We look at all of this at the free survey. Nothing is priced until the room, your daily spot in it and the roof have been seen, and the figure we then write down is final. Our electric opening rooflights page gives the wider picture. To book a survey use the quote form, or reach us on WhatsApp, 07880 284133.