NREL PVWatts Solar Production Calculator

Estimate solar PV system energy production for any US location using the National Renewable Energy Laboratory's PVWatts v8 API. Inputs latitude, longitude, system capacity, tilt, and azimuth. Outputs monthly and annual AC kWh, capacity factor, and the nearest weather station used for solar resource modeling.

Why this Actor

Solar installers, energy developers, and ESG analysts need quick PV output estimates for hundreds of sites. PVWatts is the industry-standard NREL model — this Actor wraps it for bulk runs, multi-site portfolios, and dashboards, returning structured JSON that drops into CSV/RAG pipelines without a single API call from your team.

Features

• Bulk multi-site mode: feed many lat/lon/capacity rows in one run.
• Annual + monthly AC and DC kWh output.
• Capacity factor (computed).
• Solar resource (kWh/m²/day) annual and monthly.
• Nearest weather station metadata (name, distance, elevation).
• Works with NREL's free DEMO_KEY (rate-limited) — or a free user key for unlimited use.

Output fields

Field	Description
latitude, longitude, label	Site identity
systemCapacityKW	DC nameplate
annualAcOutputKWh	Annual AC energy
capacityFactorPct	Computed capacity factor
monthlyAcKWh	12-month AC output array
monthlyDcKWh	12-month DC output array
solradAnnual / monthlySolarResource	NREL TMY solar resource (kWh/m²/day)
stationName, stationCity, stationState	NSRDB weather station used
stationDistanceMeters	Distance from site to weather station

Tutorial — How to estimate solar production

1. (Recommended) Get a free NREL API key at https://developer.nrel.gov/signup/. Paste it into NREL API Key.
2. Paste one site per line into Sites, formatted as latitude,longitude,capacity_kW. Example:

   33.4484,-112.0740,10
   34.0522,-118.2437,8
   40.7128,-74.0060,12
   

3. Choose Tilt, Azimuth, Array Type (fixed roof, 1-axis tracker, etc.), Module Type (standard/premium/thin-film) and System Losses %.
4. Run. Each site returns one record with annual + monthly output.

Leave Sites blank to estimate output for 10 sample US cities — useful for testing.

Pricing

Per-result. Each site = 1 result. Compute is minimal (single HTTPS request per site).

Use cases

• Solar installer lead qualification (rough output for proposed sites)
• ESG / RE100 corporate site modeling
• Real estate / commercial roof-leasing assessments
• Academic / consulting analyses of regional solar potential

FAQ

Q: Do I have to get an API key? No — DEMO_KEY works for small runs, but is rate-limited and shared. The free NREL key is instant.

Q: Is this PVWatts v6, v7, or v8? v8 — the current released version.

Q: What's the model accuracy? ±10% versus measured production for most US locations; NREL publishes uncertainty docs at https://pvwatts.nrel.gov/.

Legal

This Actor calls NREL's public PVWatts API. NREL data is public-domain US Government data. Respect NREL rate limits (free key = 1,000 req/hr by default).