Any solar system that generates more energy than you use is a waste. You save nothing by using a solar system at less than its full capacity. If you install a solar water heater that’s too big, you’ve wasted money. If you install an intertie system that’s too big, you get nothing for the excess power that you don’t use (although to be fair, this is changing).
Strictly speaking, you don’t have to do an energy audit and take conservation steps before installing a solar system. But bypassing these processes violates the spirit of solar philosophy. Actually, I don’t really have to put this item in this list because you’re already an environmentalist, right?