I know this law well, it's not a tax but a grid fee – you pay a c/KWh fee if panels are connected to the grid and/or use the grid for alternative supply, but not for off-grid panels. The fee doesn't specify if the panels are for personal or industrial use. Something very similar to what the state of Arizona does. That article doesn't do a very good job of explaining the raison d'être of the so-called "tax".