Retrofitting domestic appliances for PV powered DC Nano-grid and its impact on net zero energy homes in rural India

There is a growing interest in employing renewable energy conversion systems for supplying power to rural households in India. Such systems have to be designed with maximum efficiency and with minimum intermediate stages. In this context, modifications are proposed for two commonly used rural household appliances; the wet-grinder and the dough-maker for Net zero energy Homes (NZEH). In this paper, AC motors that are conventionally employed for the above two appliances are replaced by Permanent Magnet DC (PMDC) motors, thereby avoiding inverters in the system. The power electronic interfaces for the PMDC motor are also developed. Investigations have been presented to show an increase in energy efficiency and reduction in the cost of the appliances, as a result of this replacement. Roof Top Photo-Voltaic (RTPV) array is the main power source of the proposed NZEH. The new architecture of the NZEH has RTPV and loads directly powered by the PV array, thus creating a DC Nano-grid. The sizes of the PV array required for this NZEH are found to have been reduced with the proposed modifications. Analysis on embodied energy and payback period for the proposed energy system are also presented. This article also presents the energy balance study for a rural home with the new appliances.