pvkit

PV (solar) performance modeling in TypeScript (sun position, irradiance, cell temperature, DC/AC power and kWh, single-diode I-V, shading, string sizing, weather data, project economics and the CEC module/inverter database) that runs wherever JavaScript runs: browser, edge, Workers, React Native. Zero runtime dependencies, ESM-only, and every model is checked against reference implementations.

Live demo: pvkit.netlify.app, a browser-only clear-sky kWh estimate built on pvkit-js, no backend.

npm i pvkit-js

Install, quickstart, the module list and the fixture counts behind each module are in the package README: packages/pvkit.

Packages

Package	npm	What
pvkit-js		Everything in 18 modules: sun position → irradiance → temperature → DC/AC → kWh, plus diode, layout, sizer, economics, io, chain and spec (CEC module/inverter and Sandia SAPM databases from NREL SAM; a bundle carries the data only when it imports it)

apps/demo is the demo site (not published to npm).

Design

• Runs anywhere. Pure TypeScript, no backend round-trip, no WASM. SPA ≈ 18 µs/call.
• Small bundles. One subpath per method (pvkit-js/solarposition/spa) and "sideEffects": false, so a bundle carries only what it imports.
• Unit-safe. Branded Radians/Degrees types catch rad/deg mix-ups at compile time, at zero runtime cost.
• One instant per call. Scalar in/out with timeMs (UTC epoch ms), which fits realtime and streaming use; loop for a series.
• Validated. Each model is written from its paper, then its outputs are pinned as fixtures from pvlib or another independent reference; pnpm fixtures regenerates them all.

Development

pnpm install
pnpm build
pnpm test

MIT licensed; the spec module's NREL SAM data ships under BSD-3-Clause.