This is very much like the EV argument - 'it won't save the planet!' Nobody is saying solar panels are our saviour, but solar panel manufacturing still has a lower carbon footprint than other energy source. And that's what we are currently doing here on Earth - finding a better solution than the one we have already. The solar industry is already finding solutions to many of the points you raised. But maybe, in future, there will be an even better solution. For now, all we can do is cause less damage than we have been doing. And solar panels achieve that.