I'm going to have to break out my old electric textbooks and knock off a lot of rust to do the math, but will give it a shot.
It may be a longer path to get to back to where esshup started.
A fridge compressor cyces on/off based on temp where an air pump is running continuously so the battery and recharging needs are significantly higher. Even if I can DIY something at 25% of a packaged solar solution, I'm right back to the cost of a packaged grid solution. Since I'm likely doing a DIY grid solution which will be cheaper still, it's tough to justify beyond a cool and fun project.
My undergrad was in aerospace engineering, but since I'm not trying to make my pond fly I'll have to bring in my electrical engineer father for adult project supervision.
