Space Solar Array Sizing Calculator

The array area is deliberately solved backward specifically to make end-of-life power equal the requirement you entered, so every other input — solar constant, cell efficiency, degradation rate, mission duration, sun angle — only changes how much array area is needed to hit that same fixed target, not the end-of-life power figure itself. This is the calculator's intended purpose, not a coincidence: you're sizing the array to guarantee a specific power output at the end of the mission.

Begin-of-life power shows how much power the freshly-launched array actually produces before any radiation degradation has occurred, and the gap between it and end-of-life power represents the built-in overcapacity the array needs on day one purely to survive years of expected performance decline and still meet the requirement at the end. A mission with a higher degradation rate or longer duration will show a noticeably larger gap between begin- and end-of-life power for the same power requirement.

Solar power delivery to a flat panel follows a cosine relationship with the angle between the sun and the panel's normal direction, so a panel angled away from directly facing the sun receives proportionally less power per square meter — the same physical reason a solar panel performs best when facing the sun directly rather than edge-on. A spacecraft that can't always keep its array perfectly sun-pointed throughout the mission needs a correspondingly larger array to compensate for that worst-case angle.

It's a reasonable planning figure specifically for rigid solar panels, a common and well-understood construction approach, but actual array mass varies meaningfully by design — flexible, roll-out, or deployable array technologies can achieve considerably lower mass per square meter than rigid panels, at the cost of different mechanical complexity and reliability tradeoffs. Treat this as a first-pass estimate to size the ballpark mass budget, not a substitute for a vendor's actual specification once a specific array technology and supplier are selected.