Is the questioner required to pay the consumption bill for 5 amperes or 7 amperes for an electrical appliance that consumes 5 amperes from the national grid and 7 amperes from a private generator due to the generator's weak current, bearing in mind that there are other subscribers on the same generator who receive the full current?

The basic principle is that payment should be according to consumption. If the other participants in the generator are aware of the questioner's device and have authorized and consented to it, then there is no blame. The questioner must do one of two things: either pay for 7 amperes, or inform his partners about the device and seek their permission for the excess usage.