How to find out how much sun a flat gets before you buy it
A viewing shows you the sun at one hour of one day. To know the sun all year round there are two kinds of tool: those that show where the sun travels from where you are standing (augmented-reality apps and maps), and those that calculate how much direct sun reaches a window given what is in front of it. Here we compare them using data from their websites and app stores.
Comparison
App Store / Google Play prices in Spain, checked on 13 October 2026.
| Tool | What it does | Does it count the buildings in front? | Hours of sun on your window all year? | Where and price | When to use it |
|---|---|---|---|---|---|
| Sun Seeker | The sun's path over the camera view (augmented reality) and on a map, for any date. | No: you see the obstacles yourself through the camera. | No | iOS and Android · €9.99 / €9.49 | At the viewing, to see where the sun will pass from where you are standing. |
| Sun Surveyor | The sun's and moon's paths in augmented reality, on a map and in Street View; for photography, architecture, real estate and solar panels. | No: you see the buildings through the camera; on the map, the shadow of an object of the height you enter. | No | iOS and Android · €9.99 / €10.99 | At the viewing, or from home with Street View, with more planning options. |
| PhotoPills | Photography planner with the sun, moon and Milky Way, on a map and in augmented reality. | It doesn't say. | No | iOS and Android · €12.99 / €10.99 | For photography; for a flat, a first idea of the sun's path. |
| ShadeMap | Shadows from terrain, buildings and trees on a map for any date and time, with layers showing hours of sun for the day and the year. | Yes, partly: buildings from OpenStreetMap and other open sources (if they have no height, they count as one storey); paid LiDAR data in some areas. | Partly: per point on the map, not per window | Web | To explore which streets, courtyards or terraces stay in shade. |
| SunCalc | The sun's path on a map for a given day and place: sunrise, sunset, height and direction. | No | No | Web · accepts donations | To find out in a minute where the sun rises and sets. |
| Asoleo | Hours of direct sun on each window of the flat (and the terrace or roof), at the height of its floor, minute by minute for all 365 days; and in the same report, with its official source, summer heat, noise on each façade, building data, air quality, surroundings and prices. | Yes: buildings, trees and terrain with LiDAR where available (Catalonia, Navarre and the Basque Country); elsewhere, with the Cadastre's buildings, a simpler model (indicative). | Yes, per window and floor | Web, no app · €19 with LiDAR, €12 without LiDAR (VAT included) | Before viewing or making an offer, to know the sun all year round, especially in winter. |
Sun Seeker
- What it does
- The sun's path over the camera view (augmented reality) and on a map, for any date.
- Does it count the buildings in front?
- No: you see the obstacles yourself through the camera.
- Hours of sun on your window all year?
- No
- Where and price
- iOS and Android · €9.99 / €9.49
- When to use it
- At the viewing, to see where the sun will pass from where you are standing.
Sun Surveyor
- What it does
- The sun's and moon's paths in augmented reality, on a map and in Street View; for photography, architecture, real estate and solar panels.
- Does it count the buildings in front?
- No: you see the buildings through the camera; on the map, the shadow of an object of the height you enter.
- Hours of sun on your window all year?
- No
- Where and price
- iOS and Android · €9.99 / €10.99
- When to use it
- At the viewing, or from home with Street View, with more planning options.
PhotoPills
- What it does
- Photography planner with the sun, moon and Milky Way, on a map and in augmented reality.
- Does it count the buildings in front?
- It doesn't say.
- Hours of sun on your window all year?
- No
- Where and price
- iOS and Android · €12.99 / €10.99
- When to use it
- For photography; for a flat, a first idea of the sun's path.
ShadeMap
- What it does
- Shadows from terrain, buildings and trees on a map for any date and time, with layers showing hours of sun for the day and the year.
- Does it count the buildings in front?
- Yes, partly: buildings from OpenStreetMap and other open sources (if they have no height, they count as one storey); paid LiDAR data in some areas.
- Hours of sun on your window all year?
- Partly: per point on the map, not per window
- Where and price
- Web
- When to use it
- To explore which streets, courtyards or terraces stay in shade.
SunCalc
- What it does
- The sun's path on a map for a given day and place: sunrise, sunset, height and direction.
- Does it count the buildings in front?
- No
- Hours of sun on your window all year?
- No
- Where and price
- Web · accepts donations
- When to use it
- To find out in a minute where the sun rises and sets.
Asoleo
- What it does
- Hours of direct sun on each window of the flat (and the terrace or roof), at the height of its floor, minute by minute for all 365 days; and in the same report, with its official source, summer heat, noise on each façade, building data, air quality, surroundings and prices.
- Does it count the buildings in front?
- Yes: buildings, trees and terrain with LiDAR where available (Catalonia, Navarre and the Basque Country); elsewhere, with the Cadastre's buildings, a simpler model (indicative).
- Hours of sun on your window all year?
- Yes, per window and floor
- Where and price
- Web, no app · €19 with LiDAR, €12 without LiDAR (VAT included)
- When to use it
- Before viewing or making an offer, to know the sun all year round, especially in winter.
What each type of tool measures
- Augmented-reality apps (Sun Seeker, Sun Surveyor, PhotoPills): show the sun's path over your phone's camera from where you are standing. You judge by eye which building blocks it. They work at the viewing, from the window, for any date; they don't add up hours.
- Shadow maps (ShadeMap): calculate the shadow of buildings and terrain on a map using open data. They give a good idea of a street or a courtyard; accuracy depends on the building heights in those sources.
- Astronomical calculators (SunCalc): tell you where the sun is, not whether it reaches your window.
- Asoleo: calculates the sun that reaches each specific window of the flat, at its height, given what is in front of it, every day of the year. It's a report on the flat, not an app, and it also gathers, with sources, summer heat, noise, the building, air and the neighbourhood.
Best of all: use them together
- Before the viewing, Asoleo: hours of sun on each window all year and on the worst day (21 December), to rule flats out or put them in order.
- At the viewing, an augmented-reality app: see from the window where the sun will pass and check what no map shows (an awning, a tree that has grown, building work).
Asoleo's limits
- Outside the LiDAR areas (Catalonia, Navarre and the Basque Country) the calculation is indicative: it uses the Cadastre's buildings, a simpler model, with a typical error of 20–40 min a day. We tell you before you pay. And with LiDAR the margin depends on the resolution: about 5 min a day with 25 or 50 cm, about 15 with 1 m and about 20 with 2 m.
- LiDAR is a snapshot of the day of the flight: we flag buildings put up since, but it can't see awnings, blinds or small building work.
- It measures direct sun, not brightness or reflected light.
Frequently asked questions
Is there an app that tells you how much sun a flat gets?
Augmented-reality apps such as Sun Seeker or Sun Surveyor show where the sun travels from where you are standing, but they don't calculate the hours of sun a window receives, nor do they account for the buildings in front on their own. For that you need a calculation based on a 3D model of the surroundings, like Asoleo's, which gives the hours of direct sun on each window all year.
How can I tell if a flat gets sun without visiting it?
With a calculation based on a 3D model of the surroundings. Asoleo uses LiDAR where it exists (and, elsewhere, a simpler model of the buildings) to calculate the sun on each window minute by minute for all 365 days. ShadeMap gives a first idea on the map using open data.
Which orientation gets the most sun in winter?
In Spain, south, then south-east and south-west; north, north-east and north-west get almost no direct sun in winter. But orientation isn't enough: the buildings in front and the floor matter as much or more. At the Sagrada Família in Barcelona, on 21 December a south-facing façade on a middle floor gets a median of 5 h 50 min of sun, and a north-east or north-west one gets none.
Is an augmented-reality app useful at the viewing?
Yes, to see from the window where the sun will pass at other times of year and what will block it. It's a good complement to a calculation done beforehand: the app shows what you see from one spot; the calculation adds up the hours across the whole year.
Can I trust Asoleo outside Barcelona?
Where LiDAR exists (Catalonia, Navarre and the Basque Country) it calculates with measured buildings, trees and terrain, with a margin of about 5 to 20 min a day depending on the LiDAR's resolution (25 cm in Barcelona and its area, 1 m in the rest of Catalonia and the Basque Country, 2 m in part of Navarre). In the rest of Spain the calculation is indicative, with the Cadastre's buildings and a typical error of 20–40 min a day; it costs €12 and we tell you before you pay. In that case it's worth checking it at the viewing with an augmented-reality app.
How much does an Asoleo report cost and how long does it take?
€19 with LiDAR and €12 where there isn't any yet, VAT included. It's delivered in a couple of minutes, with a link, PDF and email, with no account needed. Besides the sun, it brings summer heat, noise, the building, air and the neighbourhood: what would take you an afternoon to look up on ten official websites.