It /seems/ like things are working properly BUT it is basically related to two things:
1. the heat accumulators are a huge heat bottleneck b/c they attempt to store so much of it (they function like big blocks of copper, kinda like a heat sink, more than a normal battery/accumulator) AND they are basically multiplicative in loss/bottleneck until they are completely heated -- e.g. if you are generating 100KW of heat with 1 accumulator, it will attempt to take as much of it as it can... but with 2 accumulators, each is getting half which cuts your equilibrium temperature in half!
2. heat pipes dissipate a fair amount of heat (lose heat) and even more so if in parallel to heat generators (so a patch of panels with a bar of heat pipes running along them loses a lot of heat -- you only need 1 or 0 pipes coming off a rectangular patch of panels)
The panels store enough residual heat that you shouldn't need any accumulators if playing in vanilla-ish/Nauvis-ish day/night cycle. Just get rid of the accumulators and things should work fine.
I am updating the README to basically outline this info and to have the examples NOT use accumulators for standard usage, and note that they are for planets with long nights. I am also updating the accumulator descriptions to note their approximate heat storage (which I hope I calculated correctly...).
