Estimation of the CubeSat's Available Energy for Free-Orientation Scenario

The power budget of a CubeSat is difficult to estimate when its orientation while in orbit is unknown. If the attitude control system is absent, when there was a short-term system failure or it completely failed, the satellite usually begins to rotate; in this case, the axis of its own rotation can be any. The amount of available electrical energy in free-orientation mode determines how quickly it can restore its functionality and whether it can at all. Thus, the available energy can be obtained using a statistical estimate. This article provides power budget estimates in free-orientation mode for popular CubeSat designs. To estimate the energy, one needs to substitute the parameters of the solar cells used (at the maximum power point), as well as the fill factor of the solar array panels.