# nrel.pvwatts.estimate

Calculate monthly and annual AC energy production (kWh) for a residential or commercial solar PV system at any global location. Uses NSRDB satellite-derived solar resource data. Returns monthly AC/DC energy, capacity factor, plane-of-array irradiance, and solar radiation. Unique — no other tool in this catalog estimates solar PV output.

Agent View of the PolicyLayer registry record for `nrel.pvwatts.estimate`. HTML page: https://policylayer.com/tools/io-github-whiteknightonhorse-apibase/nrel.pvwatts.estimate

## Facts

- Tool: `nrel.pvwatts.estimate`
- Server: Apibase (`apibase-mcp-client`) — https://policylayer.com/tools/io-github-whiteknightonhorse-apibase.md
- Install: `npx -y apibase-mcp-client`
- Homepage: https://github.com/whiteknightonhorse/APIbase
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 8 (3 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `tilt` | number | no | Module tilt angle in degrees from horizontal (0=flat/horizontal, 90=vertical). Default 20. |
| `losses` | number | no | System losses percentage (0-99). Accounts for wiring, soiling, shading. Default 14 (NREL recommended). |
| `azimuth` | number | no | Array azimuth angle: 0=north, 90=east, 180=south (default, optimal in Northern Hemisphere), 270=west. |
| `latitude` | number | yes | Site latitude in decimal degrees (global, WGS84). Example: 37.7749 (San Francisco), 51.5074 (London). |
| `longitude` | number | yes | Site longitude in decimal degrees (global, WGS84). Example: -122.4194 (San Francisco), -0.1278 (London). |
| `array_type` | integer | no | Array mount type: 0=Fixed open rack, 1=Fixed roof mount (default), 2=1-axis tracking, 3=1-axis backtracking, 4=2-axis tracking. |
| `module_type` | integer | no | Solar module type: 0=Standard (polycrystalline), 1=Premium (monocrystalline, default), 2=Thin Film. |
| `system_capacity` | number | yes | System DC nameplate capacity in kilowatts (kW). Example: 5 for a typical residential system, 100 for commercial. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "nrel.pvwatts.estimate",
    "arguments": {
      "latitude": 0,
      "longitude": 0,
      "system_capacity": 0
    }
  }
}
```

## Why nrel.pvwatts.estimate is rated Low

Tool retrieves solar production estimates using satellite data without creating, modifying, executing code, or causing side effects.

From the tool's own definition: "Calculate...production...Returns monthly AC/DC energy, capacity factor, irradiance"

## Use case

AI agents call nrel.pvwatts.estimate to retrieve information from Apibase without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Apibase:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "nrel.pvwatts.estimate": {}
  }
}
```

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## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-whiteknightonhorse-apibase · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-whiteknightonhorse-apibase