Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

The calculators use published formulas and rules, typed into our own code:

Solar production: rated power × peak sun hours × (1 − system losses), with 14 % losses as the default (the default system-loss value in NREL’s PVWatts documentation).
Sun position: solar declination by Cooper’s equation (1969) and the noon solar elevation 90° − |latitude − declination|.
PV circuit current factors of 125 % and 156 % of short-circuit current follow NEC 690.8; code tables are not reproduced.
Conductor resistance from resistivity (copper 0.017241 Ω·mm²/m, aluminium 0.028264 Ω·mm²/m) and AWG sizes from the ASTM B258 definition.
Lead-acid state of charge: cell open-circuit voltage ≈ electrolyte specific gravity + 0.84 V, the standard rule in battery engineering texts.
Battery runtime with Peukert’s law for lead-acid batteries; lithium-ion air-travel limits of 100 Wh and 160 Wh from FAA and IATA guidance.

No third-party code, fonts or data files are loaded by the pages (data/credits.json, rendered below).