With people and industries moving to sunny areas I see water shortage becoming an issue much earlier TTL, esp. if the likely bump in population takes place with ease of fertilizers and solar powered mechanization. Hopefully the desalination of sea water becomes cheap enough quickly.
Solar desalination was used in Chile before the POD, and it is argued that these devices provided Chilean forces with strategic advantages over Peru and Bolivia in the War of the Pacific, as Chilean locomotives had reliable access to clean water.
A condensation setup which uses Stirling cooling and concentrated solar heat should be enough to create a water still. Given that solar energy is a 'use it or lose it' deal at this point, it shouldn't matter much how efficiently the system is.
I expect that this will change as solar energy switches from heat to electricity and becomes integrated to a grid where costs of opportunity start to matter, but by that point market pressures will demand the development of more efficient solutions. Or maybe keep them separated from the grid altogether.
There migration to sunnier areas also will have societal and demographic impacts. More Europeans in tropical regions will certainly change the colonies, and how they interact with the natives.
Hindsight indeed is always 20/20, and I was just thinking out loud when I suggested it--I had to tackle some similar problems in controls class back in undergrad, so this idea is burned into my mind.
Given the cost of early PV tech, the labor to minutely adjust the direction is almost certainly cheaper for now.
Early photovoltaics will probably cause premature balding as they definitely work, but the photoelectric effect which makes them work is still unknown and can't be adequately explained without Quantum Mechanics.
Speaking of ideal solutions, one has to wonder what'd happen once early computers can register voltage as inputs. A system that could automatically sense cloud cover or when a section needs cleaning could demonstrate the benefits of automated control early in the 20th century, and from that point spread to other industries.