Satellite Power Budget
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Spacecraft Engineering

Satellite Power Budget Calculator

Compute solar array size, battery capacity, eclipse duration, depth of discharge (DoD), and EOL power in real time. Supports LEO, MEO, and GEO orbit scenarios.

Orbit Parameters
Orbital Altitude h 500 km
LEO: 200–2000 / MEO: 2000–35786 / GEO: 35786
Inclination i 51.6 °
Solar Array Parameters
Conversion Efficiency ηsa 28.0 %
Si: 14–18% / GaAs: 28–32% / 3-junction: 35%
Wiring Efficiency ηwire 95.0 %
Annual Degradation d 2.5 %/yr
Design Lifetime L 5 yr
Power Load & Battery
Satellite Load Psat 500 W
Allowed DoD 30 %
Battery Voltage Vbat 28.0 V
Orbit Period (min)
Eclipse Time (min)
Sunlight Fraction (%)
Solar Array Area (m²)
Battery Capacity (Wh)
EOL Power Ratio (%)

Key Equations

Orbit period: $T_{orb} = 2\pi\sqrt{\dfrac{(R_e+h)^3}{\mu}}$

Eclipse time: $T_e = \dfrac{T_{orb}}{\pi}\arcsin\!\left(\dfrac{R_e}{R_e+h}\right)$

EOL power: $P_{EOL} = P_{BOL}(1-d)^L$

Battery capacity: $C_{bat} = \dfrac{P_{sat} \cdot T_e}{DoD \cdot \eta_{bat}}$

Design Note: Always verify the power budget at EOL conditions. GEO satellites face eclipse periods of up to 72 minutes around equinoxes. LEO satellites cycle ~15 times per day (~5,500 cycles/year), making DoD control critical for battery longevity.
ParameterBOLEOLUnit