# SiteCheck Trade & Energy – PVWatts Solar Energy Estimator

> SiteCheck Trade & Energy – PVWatts Solar Energy Estimator is a paid API for AI agents from api.tradeenergy-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-29).

Estimates annual and monthly AC energy output, capacity factor, and solar radiation for a grid-connected PV system at a given latitude/longitude using NREL PVWatts v8 and NSRDB typical-year weather data.

## Facts

- Endpoint: GET https://api.tradeenergy-api.workers.dev/api/energy/pvwatts-solar-simulator?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-trade-energy-pvwatts-solar-energy-estimator-be8a20fe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_A4vi2qRDG1xcXIoPhFG20

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 sitecheck-trade-energy-pvwatts-solar-energy-estimator-be8a20fe
```

Example prompt: Can you estimate the annual solar energy output for a 4 kW PV system at latitude 40, longitude -105 with a 40-degree panel tilt facing south, using the PVWatts solar simulator?

## When to prefer this

Choose this endpoint when you need a quick, authoritative NREL PVWatts v8 solar energy estimate for any US (or global NSRDB-covered) location without standing up your own NREL API key. Ideal for agents performing site feasibility checks, energy audits, or comparing solar yield across candidate sites. Prefer this over generic solar calculators when you need NSRDB typical-year weather accuracy and structured monthly output in a single API call.

## Known failure modes

- Missing required lat or lon parameters returns a validation error
- Latitude or longitude out of valid range (-90 to 90 / -180 to 180) causes an error
- Location outside NSRDB coverage (e.g. ocean or polar regions) may return no weather file
- Capacity below 0.05 kW or above 1000 kW rejected as out-of-range
- Upstream NLR/NREL PVWatts API unavailability results in a gateway or timeout error
- Payment not attached or insufficient USDC causes an x402 payment-required response

## How this service works

NLR (formerly NREL) PVWatts v8 estimate for a grid-connected PV system at a latitude and longitude: annual AC energy (kWh), capacity factor, annual solar radiation, and monthly AC energy. Uses the NSRDB typical-year weather file; this is an estimate, not a yield guarantee.

## Output

Returns a JSON object with the queried latitude, longitude, tilt, azimuth, system capacity (kW), annual AC energy (kWh), an array of 12 monthly AC energy values (kWh), capacity factor percentage, annual solar radiation (kWh/m²/day), the NSRDB weather file used, US state and country, the NLR PVWatts API source URL, and the timestamp of the check.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "lat",
      "lon"
     ],
     "properties": {
      "lat": {
       "type": "string",
       "description": "Latitude, -90 to 90"
      },
      "lon": {
       "type": "string",
       "description": "Longitude, -180 to 180"
      },
      "tilt": {
       "type": "string",
       "description": "Panel tilt in degrees, 0 to 90 (default 20)"
      },
      "azimuth": {
       "type": "string",
       "description": "Azimuth in degrees, 0 to 360 (180 = south; default 180)"
      },
      "capacityKw": {
       "type": "string",
       "description": "DC system size in kW, 0.05 to 1000 (default 4)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "lat": 40,
  "lon": -105,
  "tilt": 40,
  "source": "https://developer.nlr.gov/api/pvwatts/v8.json",
  "azimuth": 180,
  "location": {
   "state": "Colorado",
   "country": "United States",
   "weatherFile": "NSRDB PSM V3 GOES tmy-2020 3.2.0"
  },
  "checkedAt": "2026-10-23T09:38:22.632Z",
  "capacityKw": 4,
  "acAnnualKwh": 6700,
  "acMonthlyKwh": [
   513,
   529
  ],
  "capacityFactorPct": 19.12,
  "solradAnnualKwhPerM2PerDay": 5.99
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-trade-energy-pvwatts-solar-energy-estimator-be8a20fe/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.tradeenergy-api.workers.dev](https://www.zero.xyz/host/api.tradeenergy-api.workers.dev/llms.txt)