Which solar APIs let you resell the data?

You want to build a solar product and sell it. Before you wire up an API, read its terms, because most of the well-known solar data sources forbid you from passing their numbers on to your customers. That rule decides what you can ship.

The ones that say no

Google Solar, Solcast, and Solargis run proprietary models, and their licences bar you from redistributing the raw data. You can use the numbers inside your own app for your own decisions. You cannot resell them, cache them for customers, or feed them into a product that hands the values back out. For a calculator your customers embed, that is a wall.

The ones that say yes

Two public sources permit commercial resale. PVGIS, run by the European Commission, ships under CC-BY, so you attribute it and you are free to redistribute. NREL's PVWatts is US-government work in the public domain, with no restriction at all. Both let you build a paid product on top of their data.

The catch: both return raw kWh. They tell you how much a system generates. They do not tell you the payback, the net present value, or the internal rate of return, and those are the numbers that close a solar deal.

Where this product sits

Solar Figures wraps the resale-OK sources, PVGIS and NREL, and adds the economics on top: NPV, IRR, simple and discounted payback, lifetime savings, and CO2. You get numbers you can show a customer and a licence that lets you do it.

Send a generation figure and a cost; get back the numbers that actually close a deal:

curl -X POST https://api.solarfigures.com/economics \
  -H "X-API-Key: sk_live_…" \
  -H "Content-Type: application/json" \
  -d '{ "annual_generation_kwh": 4200, "system_cost": 6500, "country": "GB" }'

{
  "economics": {
    "currency": "GBP",
    "simple_payback_years": 9.1,
    "npv": 4880,
    "irr": 0.097,
    "lifetime_savings": 19240
  },
  "co2_saved_year1_kg": 525
}

One honest caveat

Our yield is climate-average. We model a typical year for a location, not the exact roof, shading, and wiring you would measure on site. That makes it right for screening a lead or showing a homeowner a ballpark, and wrong for an engineering quote. Use it to qualify, and send a surveyor to confirm.

Want the request shapes? See the REST API reference.