I do not have any particular question on your second lecture. Super clear, and thank you.
One technology question: I heard a few years ago of researchers trying to create modules designed for the north side of a roof. I do not know if there is any developments in this area, but it seems like it could be an important development.
Frankly, using PV Watts (great NREL product showing that government can work), I discovered that my 15 degree north facing roof could produce energy cheaper than what I can buy it from in CT. I still am not sure I believe the analysis, but after listening to your lecture, perhaps this is true.
The best north facing modules I know of are the same ones you use to face south. It would be a good marketing technique though. Special north facing PV modules, especially designed for not facing directly at the sun. I wonder what they would do? Maybe have a special glass that reflects less at sharp angles, however if they had that, it would also work better with south facing modules. If solar cells were super expensive, they would have micro-rows of cells facing south within the PV, but PV is too cheap to worry about that.
North facing modules work especially well in Australia.
I often figure out what the difference in production would be for north vs. south facing systems with PV Watts in the different places I teach classes and in most of the US, it turns out that you get about 2/3 of the energy. That way I figure that PV on the north now is often a better investment than PV on the south roof 5 years ago, because of the declining prices of PV systems.
You see PV all over the north rooftops in Hawaii for a few reasons. The electricity from the grid is expensive, the incentives were good and they are closer to the equator.
Still, if you put PV on the north roof, they might think you were sitting around too many campfires in Australia.