impl/typescript.ts

Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.

import { roundDiv } from "./math_round_div.ts";  ← from math.round-div ^1.0.0 · built alongside by fune
import { type PvArray, type SolarEstimate } from "./energy_solar_generation_types.ts";

// watts x Kk x SF (hundredths) / (1000 W/kW x 100) is kWh.
const DIVISOR = 100_000;

function check(what: string, value: number, max: number): void {
  if (!Number.isInteger(value) || value < 0 || value > max) {
    throw new RangeError(`${what} must be a whole number from 0 to ${max}, received ${value}`);
  }
}

/**
 * Annual AC generation by the MCS method, kWp x Kk x SF, rounded half-up to a
 * whole kWh for each array; the total is the sum of the arrays.
 */
export function solarGeneration(arrays: readonly PvArray[]): SolarEstimate {
  if (arrays.length === 0) {
    throw new RangeError("a solar estimate needs at least one array");
  }
  const kwh = arrays.map((a) => {
    check("wattsPeak", a.wattsPeak, 100_000_000);
    check("kk", a.kk, 5000);
    check("shadeFactor", a.shadeFactor, 100);
    return roundDiv(a.wattsPeak * a.kk * a.shadeFactor, DIVISOR, "half-up");
  });
  return { arrays: kwh, total: kwh.reduce((sum, k) => sum + k, 0) };
}