The fixed charges of an electricity bill are monthly charges that the electricity company charges that help to cover costs such as to maintain your service, maintain the electric grid, etc.
These fixed charges do not change from month to month but may change and go up years later as the cost of things go up.
For example a fixed charge can be a monthly membership fee that you pay to the electricity company whether you use electricity or not.
That amount is paid whether you use any electricity or not.
An example would be I pay my electricity company $28.00 per month to keep my electric service established whether I turn anything on or not.
The KWH charges are what is charged for each KWH you use so the more electricity you use the more your electric bill will cost.
The less electricity you use the less your electricity bill will be.
The Fixed Charge of an electric bill is applied to recover the basic cost of electric service, independent of how much energy is used.
It is rent for using Electric's investment in equipment like poles, wires, and transformers, as well as labor to provide members with safe and reliable electric service and also do repairs of the wires, poles etc in the event of a storm or something that knocks power out.