Solar Positioning

TypeScript library that computes the position of the sun as seen by a local observer on earth.

It uses a custom implementation of the Sun Position Algorithm (SPA) for Solar Radiation Applications by the National Renewable Energy Laboratory (NREL) as described in https://midcdmz.nrel.gov/spa/.

To install:

npm install @buge/solar

Example usage:

import {calculate} from '@buge/solar';
import {degrees} from '@buge/ts-units/angle';
import {meters} from '@buge/ts-units/length';

const pos = calculate(
  new Date(Date.UTC(2020, 8, 2, 2, 31)),
  degrees(46.94806), // latitude
  degrees(7.45264), // longitude
  meters(540) // altitude above sea level
);

The altitude argument is optional as are the pressure and temperature argumentes not shown in the example above. The latter two are used to compute the atmospheric refraction at low solar altitudes. If the observer altitude is not specified, sea level is assumed. If the temperature is not specified, 21ºC is assumed. If the pressure is not specified, it is estimated from the observer altitude.