Stand-alone Solar Photovoltaic System and Its Application in Mist Cooling of Vehicle

In this article, we would like to study how to harness solar energy for car cabin cooling using standalone solar photovoltaic system. The overall design of stand-alone solar photovoltaic (PV) system is shown in Fig. 1, which consists of PV panels with maximum power rating of 120 Watt (Vmax = 17.2 V, Imax = 6.99 A) each, Yamasaki lead acid battery with 12V/40Ah each, Modified Sine-Wave Power Inverter with input voltage ranging 20-30 V and output 240 Vac. The two PV panels with total maximum output power can reach 240 W and both PV panels are fixed to a single-axis sun-tracking system. The single sun-tracking system with active sensor can allow the PV panels harness up to 90 % of maximum solar power throughout the day due to relative movement of the sun. For this case study, a prototype of stand-alone photovoltaic system was constructed for onsite data collection to predict the heats transfer to the car cabin. The feasibility of the mist cooling system to cool down the temperature of car cabin has been analysed. It is found that low ambient relative humidity is the important parameter in decreasing the heat load entering the car. The ambient relative humidity determines the mass of water evaporates and thus the amount of heat can be removed by evaporative cooling. The effectiveness of the cooling of the car through evaporative cooling is more significant in low humidity environment. From several days of observation, the car cabin temperature can reach around 66 °C during solar noon, but the mist cooling system can bring down the car cabin temperature to around 49-50 °C.