1) The power supply bar is scaled to the total max production of all energy suppliers (engines, solar, turbines). This scale does not change unless the number of suppliers change. All suppliers are automatically part of the electrical system and knowing if they can produce or not is vital info.
2) If steam production is capped out but not at max, there is a steam shortage somewhere. Color code the production bar yellow for a minor shortage and red for a severe shortage. Knowing if your steam system can output at 100% (either it can or it can't) is vital info.
3) Do not count accumulator charging as demand. Do not count accumulator supply as production. Accumulators are storage. They are neither producers nor consumers.
4) Color code the accumulator bar. Green for charging, yellow for discharging and red for insufficient power (system overload). This makes the accumulator bar more handy.
That's pretty much it! Here's a quick 4800 hour MSPaint of what the power graph looks like with these changes: The steam only system is very easy to read and understand. The system starts off good but it grows too big for its engines. Eventually your fuel runs out and your production bar immediately reveals that production is no longer optimal.
This solar power system is also not too difficult to understand. You can probably write an essay over whether the dusk power bar should be yellow or a dark nighttime green

- At dawn your solar panels over produce and charge accumulators. How much am I over producing? Oh easy, I'm producing 80MW but only using 40 MW.
- At noon everything is fully charged.
- At dusk your solar panels turn off and switch over to accumulator power. The color of the production bar (Healthy but solar is turning off) is up for debate.
- Oh no! A night time biter raid turned on the laser turrets and overloaded the accumulators. That information is immediately visible.
- The rest of the night is peaceful and awaiting the next dawn. How much power am I producing? That's right. It's night time. I'm not producing power.