Solar Resource & PVWatts Yield Scorer — Batch Site Screening

Batch solar resource assessment API built on NREL PVWatts v8 (developer.nrel.gov). Give it a list of lat/lon sites and get back annual/monthly solar production, capacity factor, and a plain-English solar-worthiness class (excellent / good / fair / poor) for each one — a due-diligence layer, not a proximity check.

Who this is for

• Solar developers & EPCs triaging a pipeline of parcels before spending engineering time on the ones with weak solar resource.
• Data-center and industrial site selectors who need "how much on-site solar could we generate here" as one input to a siting scorecard.
• CRE / real estate due diligence teams answering "is this parcel solar-worthy" for a rooftop or ground-mount lease deal.
• Solar sales teams pre-qualifying inbound leads by ZIP/address before a site visit.

This is the resource-quality layer — it complements proximity/siting screeners like BLM solar-siting-area, USWTDB turbine-proximity, and IRA energy-community-bonus (which answer "can I build here / do I get an incentive here"). This actor answers "is the sun worth it here".

How it works

For each { lat, lon, label } in assets, the actor calls the NREL PVWatts v8 API with your chosen system assumptions (capacity, module type, array type, tilt, azimuth, losses) and maps the response into one normalized output row. Two API hosts are tried in order (developer.nrel.gov, then a fallback) so a single host DNS/network hiccup doesn't fail the whole run.

Example input

{
  "assets": [
    { "lat": 33.45, "lon": -112.07, "label": "Phoenix AZ site" },
    { "lat": 47.61, "lon": -122.33, "label": "Seattle WA control" }
  ],
  "apiKey": "DEMO_KEY",
  "systemCapacityKw": 4,
  "moduleType": 0,
  "arrayType": 1,
  "tilt": 20,
  "azimuth": 180,
  "losses": 14
}

Get your own free, instant NREL API key at https://developer.nrel.gov/signup/ — the shared DEMO_KEY works for quick tests but is rate-limited (~30 requests/hour) across all anonymous users. With your own key you can batch far larger site lists.

Output fields (one row per site)

Field	Description
label	Site label from input
lat, lon	Input coordinates
host_used	Which PVWatts API host served this result
ac_annual_kwh	Total predicted annual AC energy production (kWh)
solrad_annual_kwh_m2_day	Average daily solar irradiance on the array (kWh/m²/day)
capacity_factor_pct	Actual annual output vs. full nameplate output, as a %
kwh_per_kw_year	Annual production normalized per kW of capacity — the comparable metric across sites
best_month / worst_month	{ name, ac_kwh } for the highest/lowest production months
monthly_ac_kwh	12-element array of monthly AC production
monthly_solrad	12-element array of monthly solar irradiance
station_city / station_state	NSRDB weather station PVWatts used for the simulation
station_distance_m	Distance from your site to that weather station, in meters
solar_class	Verdict: see thresholds below
errors	Non-null if this site could not be scored (bad input, rate limit, API error)

Solar-class thresholds (from capacity_factor_pct)

• excellent — capacity factor ≥ 20%
• good — ≥ 17%
• fair — ≥ 14%
• poor — < 14%

These bands reflect typical U.S. fixed-tilt rooftop/ground-mount PV performance; adjust your interpretation for tracking arrays (arrayType 2-4), which run higher.

Use as an MCP tool

This actor is discoverable and callable by AI agents (Claude, Cursor, etc.) via mcp.apify.com — Pay-Per-Event pricing and clean, field-level output descriptions make it a good chainable tool in an agent siting/due-diligence workflow (e.g. "screen these 10 candidate rooftops for solar resource before I visit them").

FAQ

How much solar energy could I generate at this address? Pass the address's lat/lon as one assets entry; ac_annual_kwh and kwh_per_kw_year give you the annual yield for your assumed system size.

Is there a PVWatts batch API? NREL's own PVWatts API is single-site per call; this actor batches any list of sites in one run and normalizes the output into a comparable table.

How do I compare solar capacity factor by location? Run all your candidate sites in one assets array — capacity_factor_pct and solar_class are directly comparable across rows since they use the same system assumptions.

What if I hit the DEMO_KEY rate limit? Get your own free key at https://developer.nrel.gov/signup/ (30 seconds, no cost). On a rate limit the actor emits a warning row for the remaining sites instead of failing the whole run.

Pricing

$8 per 1,000 results (one billable Result event per scored site — pay-per-event, automatic dataset-item billing, no custom charges).

Categories

Real estate · Developer tools · Agents / MCP servers