Solar panel setups are fairly cheap. I got a decent set of two panels and controller on Amazon for less than $300. I mounted them on a work trailer.
The compressors don't draw a ton of power. I bet you could rig something up.
This is what I'm thinking about! I just can't believe no one has had a pond with no power anywhere near and hasn't already put together a DC system.
I'm pretty sure I can get some surplus panels and maybe batteries, I just don't know if there's a DC compressor or should I go to an inverter from the batteries and back to AC.
Surely someone has already fought this battle.
