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Solar Shadow Simulator
x402
Solar Shadow Simulator is a paid API for AI agents from solar.halowerk.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).
Calculates sun position and shadow length for a vertical object at a given location, date, and time interval using the NOAA astronomical method, and reports whether a specified nearby point falls in shadow.
Price / call$0.002
Success—
StatusUnknown
How this service works
Pure astronomy and geometry on level ground: sun position by the NOAA method, shadow length as object height divided by the tangent of the sun elevation. Refraction is only applied to sunrise and sunset. Terrain slope, surrounding buildings, vegetation and diffuse light are not modelled, so a point outside the shadow can still be shaded in reality. Times are UTC.
Output
Returns a time series of shadow calculations at the requested step interval throughout the day (UTC). Each entry includes the UTC timestamp, sun elevation angle, sun azimuth, shadow length in meters (capped at max_shadow_length_m if very long or sun below horizon), and — when obstacle_distance_m and obstacle_bearing_deg are provided — a boolean indicating whether the specified point falls within the shadow cone given the bearing tolerance.
Example use cases
Garden shading from neighbor's fence
“My garden is at 51.5074° N, 0.1278° W. There's a 2-meter fence 5 meters away at a bearing of 180°. Can you simulate the shadow on July 15 in 30-minute steps and tell me when, if ever, my garden spot falls in the fence's shadow?”
Urban courtyard shadow planning
“We're designing a courtyard in Barcelona at 41.3851° N, 2.1734° E. The adjacent building is 20 meters tall. Check every 15 minutes on December 21 whether a seating area 10 meters away at bearing 90° will be in shadow — we want to know how many hours of direct sun it gets.”
Solar panel shading assessment
“I have a solar panel array at 37.7749° N, 122.4194° W that could be shaded by a 8-meter tree 12 meters away at bearing 200°. Run a shadow simulation for March 20 in 30-minute steps so I can see how long and when the shadow might reach the panels.”
Technical details
Endpoint
POSThttps://solar.halowerk.com/shadow-simulatorWhen to prefer
Use this endpoint when you need precise NOAA-method astronomical shadow length and position calculations for a vertical object at a known GPS coordinate and date. It is ideal for architectural planning, garden or solar panel shading assessments, and any use case requiring time-series shadow data throughout a day. Prefer this over general solar irradiance endpoints when the key question is whether a specific point will be in shadow, not how much energy is available. Note it does not model terrain slope, surrounding obstructions, or diffuse light — for complex 3D urban shadow modeling, a full ray-tracing tool would be needed.
Side effects
- Invalid latitude/longitude values outside ±90/±180 range returns validation error
- Date string not in YYYY-MM-DD format causes parse error
- object_height_m below 0.01 or above 1000 returns out-of-range error
- step_minutes outside 5–60 range rejected
- obstacle_bearing_deg outside 0–360 rejected
- All shadow lengths reported as capped if sun remains very low (polar winter) or object is very tall
- Result is purely geometric — real-world shading may differ due to terrain, buildings, vegetation not modelled
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| lat | number | |
| lon | number | |
| date | string | Day as YYYY-MM-DD. |
| step_minutes | integer | |
| object_height_m | number | |
| max_shadow_length_m | number | Shadow lengths above this are reported as capped. |
| obstacle_distance_m | number | Distance of the point of interest from the object. |
| obstacle_bearing_deg | number | Compass bearing from the object to that point. |
| bearing_tolerance_deg | number |
Tags
x402
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