I seem to have run into a bug: the poweroutput and heat production of solar panels seems to be inverted. My large solar panels in low Kerbol orbit only show an energy flow of 0.01, but a large solar panel in Jool Orbit had an energy flow of several hundred units. I just tried it again on a fresh install of KSP with Interstellar 0.8 and Hyperedit as the only mods and got the same results.