Look at all of that stuff! I think that’s a sub-panel coming off of the master panel. My simple understanding of this stuff is that you bring a ton of power into a space (400 Amps in our case), then you have to break it up into bite-sized pieces for all of the various needs.
The HVAC (air conditioner units) on the roof take a bunch. Then the refrigerator takes some. There aren’t many efficiency options there, but we’ve built it to be just the right size (Chris says too small) which will pay off when it comes to energy conservation. We have lighting (pretty efficient), hot water (very efficient), and some large equipment that isn’t used all the time, but when it is draws a ton of power (e.g., Robo Coupe R23, check out old posts).