Er... Hang on...

Why does this sign say AG (aerogenerador) 15?

This sign is by the site which will be occupied by the wind turbine directly in front of us.... well, less than 300 metres away, which comes to the same thing. The wind turbine to the rear of our house, the next one along the line, is AG21. AG16 should have come next!

So what's going on with this crazy numbering then? I hope they're not somehow going to cram five more wind turbines inbetween!

p.s. Why is the sign in castillion when we're in Catalunya?