Spacecraft Solar Array Sizing Calculator

What It Does

The Solar Array Sizing Calculator computes the required solar array area for a spacecraft from its bus power, eclipse fraction, mission duration, cell efficiency, and end-of-life degradation factors. Input the average load power and the calculator returns the beginning-of-life (BOL) and end-of-life (EOL) array power, the required substrate area, and the array mass for typical cell technologies (triple-junction GaAs, silicon, IMM). Includes packing factor and pointing loss effects.

Key Features

• BOL and EOL power output from cell efficiency and degradation factors
• Required substrate area for triple-junction GaAs, silicon, and IMM cells
• Eclipse-fraction-aware load matching (sizes for daytime + battery recharge)
• Pointing loss and packing factor adjustments

Why It Matters

Solar array sizing is the dominant driver of EOL power margin. A 5-year LEO mission can lose 20-30% of BOL solar power to radiation degradation, micrometeoroid pitting, and thermal cycling. Sizing the array against beginning-of-life power leaves the spacecraft underpowered halfway through its mission. Conversely, oversizing the array adds mass that could have been payload. The calculator handles the BOL-to-EOL bookkeeping so the array meets EOL load with margin without carrying excess area.

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