The station orbits at altitude h. Orbital period and shadow (eclipse) fraction come from two-body mechanics with a worst-case (β=0°) shadow geometry:
T = 2π·√((R+h)³ / GM)
eclipse_frac = acos(R / (R+h)) / π
Average continuous solar power (batteries smooth the eclipse) is the panel's peak output at 1361 W/m² and 29% cell efficiency, de-rated by the sunlit fraction of the orbit:
P_solar = A_panel · 1361 · 0.29 · (1 − eclipse_frac)
After the fixed 8 kW life-support/avionics load, the surplus is split by the construction-power slider. Robotic welders/arms run at ~65% electrical-to-mechanical efficiency, so the rest becomes waste heat that the radiators must reject (Stefan–Boltzmann, two-sided, ε=0.85, T=300 K):
Q_radiator = ε·σ·T⁴·A_rad·2
heat_load = 0.35·P_construction + 0.15·P_base
If the desired construction power would generate more heat than the radiators can reject, the sim throttles it automatically (thermal margin goes negative and the assembly rate is capped) — you can watch this happen by cranking the allocation slider up with a small radiator. Assembly rate is construction power divided by a fixed 2.4 kWh/part robotic-assembly energy cost; each module needs 600 parts. Station-keeping propellant depletes faster at low altitude, where residual atmospheric drag is stronger.