Special edition 2018

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HWWI Research Paper

Photovoltaic self-consumption after the support period: Will it pay off in a cross-sector perspective?

By Jonas Klamka, André Wolf, Lars G. Ehrlich

We quantify the cost savings potential of photovoltaic self-consumption by single-family houses with small-scale roof-top photovoltaic (PV) systems in Germany against the background of recent storage applications after the end of the legal support period. We analyze different systems where an already installed PV system is combined with battery storage and/or a power-to-heat solution (heating rod plus thermal storage). A comparison is made in terms of a household’s electricity and heating costs under cost-minimizing operation of each system. For this purpose, we carry out comprehensive simulations of site-specific PV production and determine the optimal self-consumption as well as the optimal charging of the hot water thermal storage and the battery system. We use 25 representative electricity load profiles, which differ only in the temporal distribution of consumption, to obtain a broader picture of the cost savings potential. Results suggest that the major share of the savings potential is due to direct PV self-consumption and thus concerns the electricity costs. A profitability analysis reveals that the inclusion of a hot water thermal storage and/or a battery storage system does not pay off when juxtaposing cost savings and investment expenses, at least at current prices.

Keywords: Residential photovoltaic; self-sufficiency; battery system; power-to-heat

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