In a country and an economy as big as ours, things that look "very substantial" aren't necessarily so. According to google AI, the entire solar industry employs about 280,000 people. If every single one of them was laid off, it would be a hit on the order of 0.1% of total US employment.
Unless the solar loans were especially opaque, investors knew what they were buying. They've likely hedged accordingly. Perhaps risk was under-estimated and the whacking of the solar industry in the monstrosity just passed by the GOP was unanticipated, but I doubt it will be too often fatal.
The big problem in 2008 was the opacity of balance sheets. Literally nobody knew which institutions were exposed and how they were exposed. Hell, sometimes the institutions didn't understand their own exposure (see, e.g., Howie Hubler in the Big Short -- name changed for movie but he's the guy who tanked the bank that sponsored Steve Carrell's hedge fund). I very much doubt that is the case now. Everything is too small.