Eldartford,
My stuff is made for battery power, and there are capacitors in the power supply, and I do keep my wires short to try to minimize the inductance issue too.
To answer your question, I have not noticed any change or difference if the sunlight on the solar panels changes. However, I mostly do my listening in the evening when there is no sunlight, so I don't know for certain if there might be any audible changes resulting from the varying voltage coming from the solar panels into the batteries.
In the case of my turntable, the way the battery power supply works is by actuating a relay that disconnects the charging ciruit when the TT is running. This is because the TT battery option is designed for normal homes using AC power. But I can also use it in my application.
Just to get another opinion here, what do you think might be the effects of different component's power supplies modulating the power lines(and therefore the other component's power supplies), and possibly causing some noticeable effect, especially high-power amplifiers that suck alot of juice? I admit that I am only going on a hypothetical idea with that. But I thought it couldn't hurt to keep all the power supplies independent of each other. Do you think this may be something that could use a closer look in our home audio systems?