How would your setup work, if other types of energy are introduced? Like wind-, water-generators. Or nuclear power? The simplest answer would be: clean (zero pollution) energy, normal accumulator, dirty (polluting) energy, emergency accumulator. If there were different types of energy with differen...

I'm not sure that's a good idea. What if you want to leave the chest contents alone but change what is newly requested?

If you actually want to clean out the chest it's simple enough to transfer the items to personal inventory, then get logistic robots to take it away from you.

tl;dr: Make two different types of accumulator. The power priorities will be: solar, normal accumulator, steam, emergency backup accumulator. I am new to Factorio. I have seen the pain, difficulty, and frustration in setting up an electric network that turns off the steam engines at night. The curr...