I would imagine another challenge is the transporation costs. The nearest fresh water source appears to be Sutlej River ~18 KM straightline. The nearest seawater source appears to be the Arabian Sea, ~800 KM straightline.

The cost to a problem like this would never be labor as that can be trivially automated if it ever gets costly enough. Water is expensive at these scales.

That being said, it's probable that there could be solutions here. Automated scrubber/blower might be able to get most of the efficiency back without the cost (whether integrated into the panel or a robot on a track). Could potentially use any water more judiciously too when needed (moisten a scrub rather than blasting it with water). Don't know enough about the project but I would hope the domain experts responsible for the project would have considered something I only thought about for 30 seconds & there are reasons that they don't do that.