Ok I tried in my sandbox game and I think I got my answer.

I believe it has to do with what you mentionned, the rate of chargin the accumulators to be not enough. I need more accumulators basically.

Thanks to everyone

I feel I might have expressed myself badly.

During the day, my solar panels are enough to feed my factory and they also slowly charge the accumulators. But not enough to last nights.
During the day again, the steam engines are NOT in function despite being powered.

What I am asking is:

Can I have ...

I am at a state in my factory where enemmies are attacking and I can't generate enough energy from Solar panels to charge Accumulators enough to go through the night. This makes my laser turrets go down and ennemies have been invading for multiple days now... it is a mess :P

I am trying to connect ...