This paper presents an experimental apparatus designed and built to facilitate the study of solar-assisted heat pump (SAHP) systems using the hardware-in-loop methodology. The apparatus includes an 11.6kW capacity water-to-water heat pump, a 409L thermal storage tank, a 288L domestic hot water tank, two variable speed circulation pumps, and emulation hardware representing solar collectors and conditioned building space. A complex network of piping and electronic diverting valves is used to create various energy flow paths to support fifteen different operational modes for space heating, space cooling, domestic hot water generation, and energy storage charging. The apparatus is heavily instrumented for temperature and flow measurement. Controls and data acquisition are predominantly managed using National Instruments hardware and LabVIEW software. The experimental apparatus has been installed, commissioned, and tested. The basic functionality of control and operation has been verified through testing four different operational modes and domestic hot water withdrawal emulation. The experimental apparatus can be used not only as a platform for research on a multifunctional indirect expansion SAHP system, but also allow for similar testing of less-complex related SAHP configurations.