DIY Satellite Platforms

Power Architecture

You have five parts for your power system architecture. The solar cells provide power and charge the batteries. The batteries provide power. The power bus is a PCB that provides the interconnections between things giving power and things using power. Finally, you have things using power—the satellite processor, transmitter, and sensors.

You can structure this architecture using several circuit paths.

Direct charging

Solar cells → batteries → power bus → satellite/instruments

In this configuration, the solar cells are always charging the batteries. Everything operating on the satellite is always draining from the batteries. This is the easiest configuration to design and is very robust in operations.

Managed power

Solar cells → bus → (satellite, instruments, batteries)

If you want a more intelligent power bus, you can run the solar cells into the bus, then have it choose whether to charge the batteries (if they need it) or supply excess power (past battery charging) directly to the instruments. This provides less wear and tear on the batteries and ensures no overcharging, but requires a more sophisticated electronics design. However, if you are operating in burst mode, this alternative layout provides more accurate power level monitoring because you have separated your power sources (solar cells and batteries) at the bus.

As available battery-free operations

Solar cells → satellite/instruments

This mode is rather risky. Your satellite is only on when the sun is shining. When the orbit goes dark, so does the satellite. You save on weight, as you don’t need to carry batteries. If you are doing a concept piece or art/science project, this could be viable. Your primary concern is that you have no communications capability during the dark, and your onboard processor will be rebooting once each orbit—turning on only when solar power is available. While not recommended, it is an option.