Solar photovoltaic (PV) systems, electric vehicles (EVs), and electrical storage devices are all now available off-the-shelf to homeowners both in the UK and around the developed world. Nevertheless, choosing how many solar panels to install and how much storage to buy are costly--yet poorly understood—decisions. Moreover, there is little understanding of the impact of EVs on sizing. This is due to the inherent variability of all three processes: solar generation, residential load, and EV arrivals and departures. In this talk, I will outline the problem, why it is challenging, and recent breakthroughs in my research group in producing sizing algorithms that are theoretically well grounded yet applicable in practice.