I think of the business model as the enabling “wrapper” around the “technical” solution you make happen. If you’re a plumber, it’s all the business stuff. If you’re a teacher, it might be the whole infrastructure of a school. In a non-profit, it’s the rest of the “onion” around the thing you want to do that actually makes a difference in the world.
A good (charitable) business model is scalable (in the sense of allowing you to reach the “right” size – not necessarily enormous size) and repeatable. It enables you to serve the people you seek to serve effectively and sustainably, ideally by making growth pay for itself.
This episode of Akimbo from Seth Godin is a good introduction or refresher.