Ctrl-f NSAKEY (sees nothing) — it seems the internet has forgotten the NSAKEY debacle https://en.wikipedia.org/wiki/NSAKEY

The article is written in a very terse style, but it does mention the dam happens to be (a) south facing, and (b) above the fog line, so it can produce in the winter when fog covers the lowlands. It also mentions that there is a bit of an albedo affect – the snow reflects some of the sun back up to the panels.