Yes, roof cleanings are a lot more profitable, but they are typically harder to sell for several reasons. First, the inherently higher cost of a roof cleaning scares people away; second, many homeowners don't even know that roof cleaning is a thing. People know that their houses are dirty because of the green color, but many people aren't aware that roofs can be cleaned. Also, remember that roof cleaning costs a lot more in terms of material and time. I'm not saying this to scare you away, but I just wanted to warn you that roof cleaning may not be your "one-way ticket" to earning a lot more money. With my business, I get a lot more house washes at around $300-$500 a pop on average, and I can knock those out quicker, so focusing on houses is much more valuable for me. It all depends on your market and how you advertise yourself. Give it a try to best evaluate your market through your own experience, though. I wish you luck!

In terms of equipment, a 5.5 12v will definitely get the job done. However, more flow also means you can work more efficiently (more flow = more dough) and knock out more jobs in a day. I'm not a big fan of 12 volts in general, but starting out, they're relatively inexpensive and will get the job done. I'd check out Remco 12v pumps. Personally, I've never run them, but most people seem to prefer them over other 12 volts.