Once I get nuclear power going, this is when the ratio starts not being important. The ratio at this point could be considered the most accumulator heavy, but frankly I just keep using my one solar blueprint which provides the 1:1 ratio. Here I could have been into nuclear already but other techs take precedence (I haven't started skimming off the kovarex process yet). As the factory grows and I no longer add steam engines, the role of the accumulator is more important overnight when the solar panels are dark. The role of the accumulator is to supply enough power along with steam engines when solar isn't powered on. For me it is 1:1 mainly because of the spatial design, easily tile-able and low-supply for the slow conbots out of the mk1 personal roboport, not because of any other reason. When accumulator (and solar) tech is first obtained, I establish the ratio on a blueprint. But for me, it doesn't really change at all: The Accumulator / Solar panel ratio theoretically changes during factory development.