Guide · Daylighting options compared

Heliostat vs. Sun Tunnel vs. Light Shelf: An Honest Comparison

If a room in your home is stuck in permanent shade, there's more than one way to bring daylight in - and they are genuinely different in cost, effort and result. Some need construction, some only move light a little, and one actually relocates real sunlight from the bright side of your home to the dark side. Here's an honest comparison so you can pick the right tool for your room.

Quick comparison

1. Reflective décor and mirrors

Light-coloured walls, glossy floors and a well-placed mirror redistribute the daylight a room already gets. Cheap, reversible, worth doing - but they can't add light that isn't there. In a genuinely sun-starved room the effect is small.

2. Light shelf

A light shelf is a horizontal reflector mounted above eye level on a sunny window. It bounces incoming sunlight onto the ceiling and pushes it deeper into the room, while also cutting glare near the window. It's elegant and low-tech, but it only works where the window already gets direct sun - so it helps south-facing rooms, not north-facing ones.

3. Sun tunnel / light tube

A reflective tube channels daylight from a roof dome down into the room below. It delivers real daylight and works well - but it needs a roof directly above the room, a fairly short and straight path down, and building work (a roof penetration). That rules it out for most flats, rented homes, and any room with occupied floors above it. (For the head-to-head: Heliostat vs. Solatube vs. sun tunnels.)

4. "Daylight" LED bulbs

These emit artificial light in a daylight colour, but it's still a lamp: constant, flat, and unchanging. It never gives you the intensity, full spectrum or natural movement of real sun. Useful for tasks - not a substitute for daylight. (More on this: Why "Daylight" LED Bulbs Aren't Real Daylight.)

5. Heliostat: relocate real sunlight, no construction

A heliostat is a motorised mirror that tracks the sun and redirects real daylight to a fixed spot inside - through your existing window, onto a wall, floor or ceiling. It's the only option here that takes actual sunlight from where it falls (a balcony, a sunny wall, the garden) and delivers it where it doesn't - with no building work indoors.

A modern home heliostat like ohoya:

• tracks the sun automatically and keeps a calm, slowly moving patch of daylight on your chosen spot;
• is aimed with a one-time phone AR setup - image sensor on the device: none; the images stay on your phone;
• uses a slightly convex mirror that creates no focal point, so the light arrives as a broad area; glare is handled by no-glare zones in firmware, a safe park position and the siting notes you follow;
• runs locally on your Wi-Fi - internet optional: no account needed, and everyday operation works without an internet connection (the initial AR setup needs internet once).

How to choose

• Can you build on the roof, and is the room right under it? A sun tunnel is a solid, permanent choice.
• Is it a south-facing room with a working window? A light shelf (plus reflective décor) may be enough.
• Is the room genuinely shaded - north-facing, a hallway, a basement - but there's sun somewhere on your property? A heliostat is the option built for exactly that: it moves the sun's light to the room, without construction.
• Do you only need brighter task light, not real sun? A good LED will do - just know it isn't daylight.

Frequently asked questions

What's the difference between a sun tunnel and a heliostat?

A sun tunnel pipes daylight through the roof and needs construction. A heliostat is a mirror outside that redirects sunlight through an existing window - no building work.

Does a heliostat replace windows or skylights?

No - it complements them. It sends real sunlight to a spot that your windows can't reach, using the sun that falls elsewhere on your property.

Is the reflected light from a heliostat harsh?

No. The mirror is slightly convex and creates no focal point, so what arrives is a broad patch of daylight. Glare protection is a separate matter and rests on three things: no-glare zones enforced in firmware, a safe park position the mirror returns to, and the siting notes you follow when you install it. Two sit in the device, the third one is yours.

Which option is cheapest?

Reflective décor is cheapest but does the least. Sun tunnels and heliostats deliver real daylight; the heliostat avoids construction, which is often the bigger cost and hassle.