The electricity bill is paid the same way as the bill for mobile phone calls. Each FairBox is assigned a separate power account. To function, the account must be preloaded. Power consumption decreases the account, PV while power fed to the grid increases it. When a certain amount is exceeded, a transfer to a bank account is initiated.
At low balance, e.g. equalling three days basic load, the customer receives an SMS with notification of the account balance. Then, large loads such as air conditioners then cannot start or will be switched off. With an account balance corresponding to two days of basic load, the power will be interrupted for a few minutes after notification via SMS. When the account is empty, the power supply is switched off.
The Fair Box is equipped with a Wi-Fi modem and a data logger for recording relevant data. The power consumption and the electricity cost can be displayed with the help of an app on a smart phone. Graphical evaluations on power consumption and supply facilitate the overview and are intended to educate electricity customers to save energy and to use energy efficiently.