Forget about which generator is best, they all produce the same thing - a predominantly ionic silver solution, so you can please yourself which one you get. It's more about the quality of water used and what happens AFTER the solution is produced with regard to any impurities within that water, and what is sucked into the water from the environment or atmosphere during and after production.
And forget about particle size, so don't be guided by any TEM image or suchlike you find in the public domain. Laboratory imaging is nothing like the body/blood, they don't give a true picture of particle dispersion, they are a meaningless sales pitch. Follow appropriate production guidelines for LVDC home produced stuff and you won't go wrong.
Solar? Well, someone else can comment on that, not within my area of interest.