I was reading about micro-inverters, which are becoming a more popular option over string-inverters for grid-tied solar. The idea with microinverters, is rather then have a big inverter, you have many small ones, which use smaller film capacitors which are less likely to fail. You also get the advantage of having MPPT tracking on each panel seperately. But what if you just want DC power out of each panel, but don't want to the disadvantage of connecting a large number of panels in series and hooking it up to a centralized solar controller? You could use a power optimizer, which adjusts the resistance of the power floating out panel to get the maximum output from each individual panel. I would imagine you would also use a solar controller to avoid overcharging your batteries, and floating them when the proper time comes. Interesting stuff.