# Halowerk Solar Clear-Sky Yield Calculator

> Halowerk Solar Clear-Sky Yield Calculator is a paid API for AI agents from solar.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).

Computes the theoretical maximum daily solar energy yield for a single PV panel under cloudless-sky conditions using astronomical and geometric models, returning hourly/sub-hourly irradiance and integrated energy output.

## Facts

- Endpoint: POST https://solar.halowerk.com/clear-sky-yield
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-solar-clear-sky-yield-calculator-1596abd5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_T14qMHrp6SVI8nzEOF5ZD

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-solar-clear-sky-yield-calculator-1596abd5 -d '<json body>'
```

Example prompt: Calculate the clear-sky solar yield for a 415W panel at latitude 48.85, longitude 2.35 on 2025-07-15, tilted 30 degrees facing south (azimuth 180), at ground level, using a system derate of 0.8, and include the 15-minute power series.

## When to prefer this

Choose this endpoint when you need a fast, physics-based upper-bound estimate of daily solar yield for panel sizing, off-grid system design, or feasibility studies — especially when you have precise GPS coordinates, panel specs, and a specific date. It is not a weather forecast and does not account for clouds or shading, so use it as a planning ceiling rather than a production forecast. Prefer this over weather-coupled irradiance APIs when you want a deterministic, repeatable geometric baseline without needing real-time meteorological data.

## Known failure modes

- Invalid latitude/longitude values outside allowed ranges return validation errors
- Date strings not in YYYY-MM-DD format are rejected
- panel_wp below 1 or above 100,000 causes schema validation failure
- system_derate outside 0.1–1.0 range is rejected
- Polar locations near solstice extremes may produce edge-case irradiance results
- elevation_m outside -500 to 6000m range causes rejection
- step_minutes below 5 or above 60 is invalid

## How this service works

This is an astronomical and geometric calculation, not a forecast. It assumes a cloudless sky and states the models used; real yield is lower whenever there is cloud, haze, snow, soiling or high cell temperature. The system_derate factor covers cabling, controller and temperature losses as one flat number and defaults to 0.8. Shading is not modelled here. Times are UTC. Use the figure as an upper bound for sizing, not as an expected daily production.

## Output

Returns a computed clear-sky daily energy yield in watt-hours for the specified panel, plus an optional time-series of per-step plane-of-array irradiance and instantaneous power values at the requested resolution (default 15-minute intervals). The result represents a theoretical upper bound assuming perfectly clear skies; real yield will be lower due to clouds, soiling, shading, and temperature effects.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "lat": {
   "type": "number",
   "maximum": 90,
   "minimum": -90
  },
  "lon": {
   "type": "number",
   "maximum": 180,
   "minimum": -180
  },
  "date": {
   "type": "string",
   "description": "Day as YYYY-MM-DD."
  },
  "albedo": {
   "type": "number",
   "default": 0.2,
   "maximum": 1,
   "minimum": 0
  },
  "panel_wp": {
   "type": "number",
   "default": 415,
   "maximum": 100000,
   "minimum": 1,
   "description": "Module rating at standard test conditions."
  },
  "tilt_deg": {
   "type": "number",
   "default": 30,
   "maximum": 90,
   "minimum": 0
  },
  "azimuth_deg": {
   "type": "number",
   "default": 180,
   "maximum": 360,
   "minimum": 0,
   "description": "Module azimuth, 180 is south, 0 is north."
  },
  "elevation_m": {
   "type": "number",
   "default": 0,
   "maximum": 6000,
   "minimum": -500
  },
  "step_minutes": {
   "type": "integer",
   "default": 15,
   "maximum": 60,
   "minimum": 5
  },
  "system_derate": {
   "type": "number",
   "default": 0.8,
   "maximum": 1,
   "minimum": 0.1
  },
  "include_series": {
   "type": "boolean",
   "default": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-solar-clear-sky-yield-calculator-1596abd5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from solar.halowerk.com](https://www.zero.xyz/host/solar.halowerk.com/llms.txt)