Many people have hard earned Solar Installations but nothing much to plug into them. Oh sure there are the usual fans and light bulbs that run on 12 Volts, or the other stuff that needs to be run off an Inverter, but what about the stuff that runs off lower voltages like 4.2 Volts or 9 Volts. All this presupposes you have a Power Distribution Panel found in, '(16) https://www.instructables.com/id/Power-Distribution-Panel-For-Pluggables/ You will find some ideas in this collection for converting the stuff you already have. It's easy. Try it you'll like it and the cost is almost nothing.
It's always nice to be able to plug in a 6 Volt radio to a 12 Volt-200 Amp Hour Battery. Sucker will run forever.
Got Light? These things come three to a pack, cost about $30 and are very bright. I put individual switches on them.
Use up all that Wall Wart Wire you have laying around. What are ya saving it for? This is the way to go with it. I like Wart Removers. LOOK ! There's 8 Watts ya didn't have before! Plus the losses plugging a Wart into an inverter is insanity.
I got tired of buying batteries for this thing only to get one label out of them and finding these expensive AA's dead. Why convert 12 Solar Volts to 110 Volts only to convert the voltage back down to 6 volts with a Wall Wart. Besides there is no Wart for this thing. Ya like warts? I don't.
The need to measure the power coming in from Solar vs; the power going out to devices being used is always desirable.
A Power Distribution Panel is needed to power the various things you want to plug in. No, all your equipment does not use the same voltage so you need to make the proper operating voltages.