We have solar and A/C (for our whole building). The part of the warehouse with solar is actually our back warehouse with a flat roof (back warehouse has emb, DTG printing). Our south part has the screen printing with 6 house sized HVAC units spread throughout. It would hit 105-110F without A/C in screen printing (south side, has skylights). So we definitely like the A/C being everywhere..but of course it costs a decent amount. You can tweak it with what level of A/C you say is okay though. I suggest it after working in 115F and dripping sweat as I printed back in the day. Our dryers are ducted out of the roof straight up, end of dryer and the exhaust blower (Sprint 3000s).
As for the solar, if it saves $700 a month, how much does it cost a month? What size array? I like solar and have it at home as well (2 arrays at that, one powers my car for 8000+ miles a year). Commercial power is so much less expensive but we do have net metering. Unsure on the ROI, I would have to ask the CFO. My home solar ROI is 6 years on the array I installed myself and 12 years on the array I paid to have installed last year. I also have net metering though which is huge for ROI.
I would do all of the upgrades you can afford. They are all great ones.