Can someone tell me how much power I can pump through this shed. It has this box in it..
I read online that you do amps x volts = watts so that would mean at 120 v I can run 12,000 watts, is my math wrong?
Need to look at amps not watts
How many amps are you running per line, etc.
80% max load per breaker, so looks like you have 15 usable amps per breaker (both of them being 20/20 split breakers) now you have a total of 60a to work with. Look at the appliances you have attached to each breaker. subtract those given amps and then account in your grow amperage.
If you pull that cover, I bet there is another open breaker.
I would run a dedicated 30a/220v 14-12g line and breaker, run it directly to your grow area and use it for your lights. It will make your use of the A/C much easier on your system, plus leaves you with room for expand ability at a minimal cost (plus the safety of it)
edit:
looks like a sub panel, check the amperage at the main panel/breaker too