Because electricity can be fed into the distribution grid, grid restrictions are with a moderate penetration of RES actually not the limiting factor. But with a higher amount of decentralised production the transport capacity of the grids will be reached. Variable tariffs give a soft stimulation for operators to shift their operation schedule.

In [6] the Association for Electrical, Electronic &Information Technologies (VDE) suggests a feed-in tariff based on the day-ahead price at the European Energy Exchange in Leipzig (EEX). To the variable EEX-price a constant bonus for decentralised plants will be added during the high demand time from 6 am to 1 am. In the following this scenario will be called VDE.

The described grid in section 1 defines a very weak grid, where the global VDE-tariff might not control decentralised plant sufficient. For an efficient grid operation it is desirable to produce most of the needed power within the grid. For that reason we modified the constant bonus in the VDE-tariff to a local component. This scenario will be called LOCAL. For that the net load (difference between electric load Pel and photovoltaic production PPV) was used. This load was spread to a local time dependent bonus with a minimum at 0°cent and the mean value at the bonus in the VDE-scenario. If the missing power is large the tariff will be high to stimulate further decentralised generation.

To compare the results we assumed the typical constant feed-in tariff for cogeneration in Germany, which is called KWK-G.