This paper presents a survey of solutions for simultaneous wireless information and power transfer (SWIPT) for IoT networks. Radiative and nonradiative solutions are compared for a variety of criterion including key design elements, applications, spectrum, operating distance, modulation, data rate and efficiency. Nonradiative solutions with coupling coil architectures typically operate at frequencies of a few hundred MHz or below and achieve operating distances up to about 8 cm for designs that incorporate nonlinear metasurfaces. Radiative solutions at or close to microwave frequencies achieve operating distances up to about 400 cm for co-located shared aperture, single channel-based architectures. End-to-end efficiencies for SWIPT networks are quite low, particularly for radiative solutions, highlighting an important direction for future hardware development.