This paper simulates the impact of battery sizingfor an actual nearly-zero energy (NZEB) single-family housewith solar PV located in Bor°as, Sweden. Simulations are done,using measurement data as an input, for three different batterydispatch algorithms with two different purposes; (i) peak powershaving and (ii) maximising system self-consumption (SC) andself-sufficiency (SS) of the solar PV. The results show that theoptimal battery storage size for this single-family house, givenits measured electrical loads and existing solar PV system isaround 7.2 kWh. System self-consumption and self-sufficiencyfrom generated solar PV increased with 24.3 percentage pointscompared to a reference case without battery. Furthermore,results show that increasing the battery size beyond 7.2 kWhonly results in minor performance gains.