They were not photovoltaic solar panels, but solar water heating panels - i.e., running a ton of water pipes on the roof where they're perfectly placed to leak and potentially damage historically-significant artifacts. I'm not surprised they removed them when resurfacing the roof (not right when Reagan entered office, but in 1986).

George W. Bush actually installed solar water heating once again, but on the roof of a maintenance facility, which I didn't know about: https://en.wikipedia.org/wiki/Solar_power_at_the_White_House