Why qualification matters more here than in most businesses
A solar site visit typically involves travel, a technician or engineer, and a chunk of a working day. That is a substantial cost per enquiry, and it is incurred before any commitment exists. In most sales processes the expensive step happens late; in solar it happens early, which inverts the usual advice about qualifying gently.
The result is that a solar business lives or dies on the quality of the phone conversation before the visit. Installers who visit everything are subsidising site surveys for people comparing quotations from five providers, and the cost shows up as thin margins rather than as an identifiable problem.