More generally, the trade off is: buying/deploying more panels. So adding water cooling adds materials and work and potential repairs etc. Translate that into

More generally, the trade off is: buying/deploying more panels. So adding water cooling adds materials and work and potential repairs etc. Translate that into money, and use that to buy and install more panels, which one wins? Same applies to more efficient panels, trackers that follow the sun and most other solar innovations. As panel prices drop the calculus shifts more and more towards more panels. There are some constrained environments that drive innovation in size/weight or whatever but the mass market is driven by electricity output/dollars.