Modelling PV self-consumption at portfolio level

Self-consumption of the energy generated by photovoltaics (PV) plays an increasingly important role in the power grid. “Prosumer” systems consume part of the produced energy immediately to meet the local demand reducing the feedin into as well as the demand from the grid. As PV generation and consumption profiles are diverse and heterogeneously distributed, the adaptation of feed-in and grid load estimates is a complex task. In order to analyse the effects of PV self-consumption in the power grid, we introduce a stochastic bottom-up model of PV power generation and local consumption in the control area of the German transmission system operator TransnetBW. We set up a realistic portfolio of more than 100,000 PV/prosumer systems to generate representative time series of PV generation, self-consumption and feed-in. The model allows to investigate their time-dependent behaviour in detail for the full portfolio whereas measurements are presently only available as aggregated feed-in time series over a non-representative subset of systems. We analyse the variation of self-consumption with PV generation and consumption at portfolio level and its seasonal, weekly and diurnal cycles. The results are expected to be helpful to identify suitable parameters for data-driven models of PV self-consumption and feed-in.