There are very few people working in Alternative Energy who restrain themselves from making grandiose statements, but Bill Gross of eSolar is one of the few who sticks to the facts, and clearly has worked hard to get through (not around) the challenges. Here is a tech entrepreneur who really understands the big themes: energy density, the cheapness of coal, the problem of scale, and the tight margins in both capital and energy terms that can be so decisive as solar competes to become economically competitive. This is actually quite an amazing interview that Gross gave this week to Henry Blodget of The Business Insider. For you energy bugs, pay close attention to Gross’ discussion surrounding the diffuse nature of sunlight, and his keenly spot-on obsession with controlling all the manufacturing variables to perfection. If there’s a place where the best of energy and entrepreneurship can ever meet, it’s here. Must watch video.