Quantifying self-consumption linked to solar home battery systems: Statistical analysis and economic assessment

•PV self-consumption with or without battery is evaluated for many households in EU.•Self-sufficiency cannot exceed 80% without excessively oversizing the system.•A simple equation is proposed to compute self-consumption from PV and battery sizes.•Economic optimizations indicate that further decreases in battery costs are required.

The recent development of new and innovative home battery systems has been seen by many as a catalyst for a solar energy revolution, and has created high expectations in the sector. Many observers have predicted an uptake of combined PV/battery units which could ultimately disconnect from the grid and lead to autonomous homes or micro-grids. However, most of the comments in social media, blogs or press articles lack proper cost evaluation and realistic simulations. We aim to bridge this gap by simulating self-consumption in various EU countries, for various household profiles, with or without battery. Results indicate that (1) self-consumption is a non-linear, almost asymptotic function of PV and battery sizes. Achieving 100% self-consumption (i.e. allowing for full off-grid operation) is not realistic for the studied countries without excessively oversizing the PV system and/or the battery; (2) although falling fast, the cost of domestic Li-Ion storage is most likely still too high for a large-scale market uptake in Europe; (3) home battery profitability and future uptake depend mainly on the indirect subsidies for self-consumption provided by the structure of retail prices; (4) the self-sufficiency rate varies widely between households. For a given household, the volume of self-consumption cannot be predicted in a deterministic way. Along with these results, this study also provides a database of synthetic household profiles, a simulation tool for the prediction of self-consumption and a method for the optimal sizing of such systems.