Sounds like a fun project for your students! First, a disclaimer, our design has been more of an experimental prototype, so please don’t take this information as authoritative. From our experience this system works, but you may be able to alter it to perform better for your needs. We were operating off of a lot of unknowns…for example how much aeration do we really need keep our tea aerobic and keep our microbes fully in suspension?
With that said, here is what we did:
We knew we wanted this to run on solar, and ideally it would have the capacity to aerate continuously for 24 hrs when we are brewing. So we sized our system accordingly. Our list of components includes: a DC diaphragm air pump that produces 38L/min of air, a solar charge controller, a 12 volt 100 amp-hr lead-acid battery (deep cycle for solar systems), a 100 watt panel, and a 55 gallon barrel with a homemade pvc aerator. We kept our costs lower and efficiency higher by finding a DC air pump. This way we could eliminate the need for an inverter to power an AC pump. I have pictures of each of the spec plates for each component.
Pictures in order of appearance: solar compost tea brewer, air pump, battery, solar panel, and charge controller.
Hope this helps!