You can get watts by defeating the rare glowing Pokémon but it's only like 100 ish watts per defeat or capture. I'd suggest that you're just forgetting about a location and there's raid left somewhere.
I'm not certain but some mechanics in the game have in-game timers, which means if you try to cheat by changing your switches clock it'll penalise you by forcing you wait even longer. It's possible this has happened, but more likely you just can't find one