you said on reddit it was supposed to be 100 gigawatts, i think you missed a few zeros.

i only tested the 3rd tier factory if that helps.

You increase/decrease the limit by mousing over the arrow pointing at the substation inside and using the hotkeys.

"You can also use Shift+rotate or Ctrl+rotate to change the maximum amount of power that is transferred, up to a whopping 100GW!"

oh, guess i missed that. what a strange feature.

It's due to the tradeoffs involved in the electrical transfer buffer. Higher wattage requires a larger buffer, which can cause issues with the distribution of electricity during brownouts and generally give your electrical grid a lot of hidden baggage. So: By default, the limit is much lower.