Guide · Daylighting basics
What is a heliostat? How mirror-based daylighting works
A heliostat is a mirror on a motorised mount that tracks the sun across the sky and continuously reflects its light onto one fixed target. Unlike a solar panel, it doesn't make electricity — it moves real daylight to a place the sun never directly reaches.
The short definition
The word comes from the Greek helios (sun) and statos (stationary): a heliostat keeps the sun's reflection standing still on a chosen spot, even though the sun itself keeps moving. To do that, a small computer calculates where the sun is and slowly re-aims the mirror all day long — from sunrise to sunset, season after season.
How does a heliostat work?
Every heliostat combines three things:
- A reflective surface — a flat (or lightly shaped) mirror that bounces sunlight toward the target.
- A two-axis mount — motors that rotate the mirror horizontally (azimuth) and tilt it vertically (elevation).
- A control system — software that knows the sun's position for your exact location and time, and keeps the reflected beam locked on the target.
The sun's path is completely predictable, so the sun's position can be computed from a clock, the date and your GPS location — no internet connection required. Better systems add sensors or a camera to fine-tune the aim and to keep the beam away from people's eyes.
Heliostat vs. solar tracker vs. light tube
| Heliostat | Redirects visible daylight to a target you choose. Movable, controllable, retrofittable. |
|---|---|
| Solar tracker (PV) | Aims a solar panel at the sun to generate more electricity. A different purpose — not for lighting. |
| Light tube / sun tunnel | A fixed, passive shaft that pipes daylight through a roof. Cannot be moved or aimed, and needs building work. |
What are heliostats used for?
Historically, heliostats were built for science (keeping a telescope or instrument lit by a steady sunbeam) and for concentrated solar power towers, where fields of large mirrors focus sunlight onto a central receiver. More recently, compact residential heliostats have brought the same idea home: instead of powering a turbine, they place a warm patch of real sunlight exactly where architecture forgot to.
Typical home uses include waking up a north-facing room, lighting indoor plants, reclaiming a shaded terrace in the afternoon, or putting morning sun on the breakfast table.
Can you use a heliostat at home?
Yes — and that's exactly what the ohoya Heliostat is built for. It mounts outdoors (on a ground anchor, wall or mast), tracks the sun automatically using on-device computation, and steers daylight through a window or onto an outdoor seating area. Control is local via an app, with no cloud account required, and a built-in safety system keeps the beam away from people's eyes.
Bring real sunlight where you miss it
The ohoya Heliostat is in its founder pre-launch. Reserve your place from €49 — fully creditable toward the price, refundable any time, no purchase contract.