Solar Panels

A 3U CubeSat has 14 available 1U 10x10 cm sides. In this design, we attach 11 NanoPower Solar P110U-A/B solar panels on 11 of the 14 available 1U sides. The remaining sides are left available for the imaging, communication, and payload systems. Each solar panel outputs an experimental ~2.3 Watts to a lithium-ion battery pack when fully illuminated by the sun at LEO. The Intrepid Platform includes an 18.5 W-hour lithium-ion battery pack and a power control board with regulated DC output buses. The solar panels in combination with the battery pack have been simulated to be sufficient for imaging and high capacity data transmission   

NanoPower Solar P110U-A/B [1]

We assume that at any point during exposure to the sun (conservatively half of an orbital period), a conservative average of 2 of the 11 panels will be operating at full capacity, each panel converting ~28% of incident solar power to electrical power. The following formula computes the energy that the solar panels will generate per orbital period:    

Power Capacity Per Orbital Period

In the constellation simulation, the battery charge is plotted for a single cubesat in the constellation with a more conservative 3.5 W-hours of energy generated per period. The X-band transmitter and antenna consume the most power at ~12 W, but are only transmitting during a short period of time (~10 minutes per communication pass) and thus don’t significantly deplete the battery charge. Since the cubesats generate more power than they consume during an average orbital period, the battery charge remains nearly full throughout the mission.

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References
[1] - http://www.cubesatshop.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=71&category_id=17&option=com_virtuemart&Itemid=79