Solar array site and saved summary

How the precision is kept

The array's own place is found from the project's coordinate system at the middle of the region and is rounded before it is kept. The yield is rounded to whole kWh in the saved summary.

2 calculations in 1 source file. The code is read from the released app when this page loads. It is the calculation people run, not a copy kept for this page.

export async function crsSite(project, poly) {
  const crs = project.state.crs;
  if (!crs || !poly?.length) return null;
  try {
    const { frame } = await import('./crs.js');
    const c = poly.reduce((m, p) => ({ x: m.x + p.x / poly.length, y: m.y + p.y / poly.length }), { x: 0, y: 0 });
    const [lon, lat] = frame(crs).toLonLat(c.x, c.y);
    return Number.isFinite(lat) && Number.isFinite(lon) ? { lat: Math.round(lat * 1e5) / 1e5, lon: Math.round(lon * 1e5) / 1e5 } : null;
  } catch { return null; }
}

export function summaryOf(plan, y = null) {
  if (!plan?.ok) return null;
  return { count: plan.count, modules: plan.modules, kwp: plan.kwp, ...(y?.ok ? { kwh: Math.round(y.res.total.acKwh) } : {}) };
}

In detail

Method

Mean of the region corners, projected back to longitude and latitude by the project's coordinate frame, then rounded.

Number types

64-bit numbers throughout.

Tolerances

Latitude and longitude are rounded to 1e-5 degree, about 1.1 m of latitude.

Limits

The rounded site position is what the solar plan then uses.

Approach: 64-bit, stated limit

The arithmetic is 64-bit, but the method or the data sets the accuracy: a solver tolerance, a mesh, a step size, a datum shift, a table. The limit is stated where the result is shown.

Every policy that takes this approach