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. Some 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 glare protection is built in - the mirror is convex, so there is no focal point.
What to look for in a home heliostat
- Real tracking, not a fixed mirror. It must re-aim continuously as the sun moves, not just sit at one angle.
- Honest optics. Look for “redirects real daylight” and “creates no focal point” - be sceptical of anything that talks about “focusing” or “concentrating” sunlight into your home.
- Privacy by design. No camera on the device; if the app uses your phone’s camera for AR setup, those images should stay on your phone.
- No cloud required. No account needed, and everyday operation should be independent of an internet connection (initial setup can need internet once).
- “Matter-ready” and sensible mounting. Prefer open smart-home compatibility over a closed app-only system, and mount it where the sun already reaches - with nothing to build indoors.
Frequently asked questions
What does “heliostat” mean?
It’s a mirror that tracks the sun so its reflected light stays aimed at one fixed spot - from the Greek helios (sun) and statos (standing).
Is a home heliostat the same as a solar panel?
No. A solar panel makes electricity; a heliostat is a mirror that redirects the actual daylight into a room.
Does a heliostat concentrate sunlight?
Ours does not. The ohoya Heliostat uses a slightly convex mirror and creates no focal point - it spreads a broad area of daylight instead of bringing it to a focus. A heliostat is only a mirror on a mount, so whether a given one creates a focal point depends on that mirror; this is a statement about ours, not about the category.
Does it have a camera or need the cloud?
The device has no camera, ever - the app uses your phone’s camera only for the one-time AR setup, and the images stay on your phone. No cloud is required either; everyday operation works without an internet connection (initial setup needs internet once).
How do I get a home heliostat?
The ohoya Heliostat is available as a refundable reservation - not a purchase. Deliveries are planned for the EU from H1 2027 and for the US after FCC certification.
Can I build a heliostat myself?
In principle, yes: you need a mirror, a two-axis mount with motors and a controller that calculates the sun's position. The hard parts are precise calibration, weatherproofing, wind safety and making sure the reflection never dazzles neighbours or traffic. Our guide DIY heliostat covers what it takes.
Does a heliostat work on cloudy days and in winter?
It needs direct sun on the mirror. Under a closed cloud cover there is no sunbeam to redirect. In winter the sun is lower and the days are shorter, but whenever the sun reaches the mirror, a heliostat can redirect it, for example into a room the low winter sun no longer reaches. The free Sun Check estimates the hours for your window.
Can I reserve from the US?
Yes. Reservations are open in the US and the EU and fully refundable at any time. US deliveries follow after FCC certification. This device has not been authorized as required by the rules of the Federal Communications Commission. This device is not, and may not be, offered for sale or lease, or sold or leased, until authorization is obtained.
Bring real sunlight where you miss it
The ohoya Heliostat is in its founders reservation phase. Reserve your place from €49 - fully creditable toward the price, refundable any time, no purchase contract.
Not sure how much sun your window gets? The free Sun Check works it out for your location. Or join the waitlist for every milestone update.
This device has not been authorized as required by the rules of the Federal Communications Commission. This device is not, and may not be, offered for sale or lease, or sold or leased, until authorization is obtained.