The performance parameters of load needs to be settled before the agreement between DSO and consumer is signed. These are usually the amount of reserved input power and annual or month reserved power for major-consumers. Consumers connected to 0.4 kV voltage level select the dimension of main circuit breaker.
These parameter should be set with needed tolerance so the regular paymant would be as low as possible. The best practice how to achieve such a goal is to made measurements of power flow in point of connection and determine the maximum input power or modify the appliances working profile to minimize the consumption during peak period.
Our company is capable to measure consumer's overall and partial consumption so he could make reliable decision how to set power parameters of load. These measurements are usually carried on during one week or during one day in simply enough cases.