Federal Network Agency Releases Position Paper on Improved Forecasting and Accounting for Solar Power Input

The rapid expansion of PV installations causes considerable problems with respect to the forecast, the sale and the billing of electricity generated by PV installations, the Federal Network Agency (Bundesnetzagentur) found. Therefore Bundesnetzagentur released a position paper for improved forecasts and  accounting of solar power input.

Currently, there are considerable discrepancies between the solar energy sold at the energy exchange by the transmission system operators (TSOs) and the actual daily amounts of solar energy generated and fed into the grid. This has significant implications for system stability, Federal Network Agency says. The discrepancies arise because for almost 75% (roughly 7.5 MW in late 2009) of the PV installations output is not measured. Hence, real 15 minute interval measurements are not available. The TSOs therefore sell solar energy mainly according to a standard profile that they get from the distribution system operators (DSOs). The problem is aggravated by the fact that TSOs do not receive timely information about new PV capacities from the DSOs, the Federal Network Agency points out.

In order to enable TSOs to sell solar energy in compliance with the Renewable Energy Sources Act and the Equalisation Scheme Ordinance, the Federal Network Agency suggests to proceed as follows:

  • The DSOs shall establish a suitable reference measurement system in cooperation with TSOs that reflects the actual power input of PV installations connected to their grid in 15-minute intervals. Implementation shall occur until spring 2011.
  • Until implementation of the reference measurement system by the DSOs, they are requested to submit input profiles to the TSOs that reflect the actual input to the greatest extent possible. This includes day and night profiles as well as profiles reflecting the seasonally expected hours of sunshine.
  • The TSOs are asked to approach the DSOs quickly to implement the above procedures. A staggered implementation starting with large DSOs shall be possible.
  • The DSOs are asked to fulfill their obligations pursuant to the EEG and inform TSOs without delay about the capacity and location of new PV capacities connected to their grid. Notifications have to be made at least once a month. They have to include all applications for interconnection of PV installations made in the past month  Should notifications only be possible with a delay of several months due to an extensive expansion, DSOs are required to give best knowledge monthly estimates.

Source: Federal Network Agency

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