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Item Novel slow switching technique for efficient solar energy harnessing for off grid photovoltaic systems(proceedings of the 4th International Research Symposium on Pure and Applied Sciences 2019, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.; Kularatna, N.Electricity consumers in remote areas where the grid connection is not available rely on diesel generators or off grid photovoltaic (P V) systems. These PV systems uses battery banks as backup energy storage. Those battery banks are charged by using a battery charge controller connected to a PV array. Because of the recent advances in solar charge controllers, they can reach maximum of 90% charging efficiency, where 10% will be unutilized. Since the efficiency of conventional solar panels lies around 20-25% which is relatively low as compared to other energy generation methods, it is important to utilize as much energy as possible produced by the solar panels. Also, when driving loads, energy stored in the battery bank again goes through a converter or inverter by wasting considerable amount of useful energy. Hence, the purpose of this study is to minimize the energy loss of the charging process of the battery bank while using the energy produced by the PV array in an effective manner. In previous publications, it was introduced a novel way of using supercapacitors (SCs) in an off grid PV system. When charging an empty capacitor in parallel with a source, 50% of energy is wasted irrespective of the value of total loop resistance. In contrast, by connecting a SC bank in series with a typical solar charge controller, it was shown that the energy loss of the combined system is less than the energy loss of parallelly connected SC bank and the battery bank in their individual systems. Experimentally, it has been shown that a 9% increment in overall charging efficiency of the combined system when a charge controller having 80% of efficiency is used to charge the battery bank in typical off grid PV system. The present study introduces a possible method of utilizing the energy stored in SC bank in an effective manner using an intelligent electronic switching scheme. The proposed method uses a second SC bank along with the existing one along with a smart electronic switching circuitry which is able to switch each SC bank between charging or discharging stages when necessary. When one SC bank is in its charging state, the other SC bank will be in its discharging state through a proper load. After that, when the first SC bank is fully charged or the second SC bank is fully discharged, positions of each SC bank is swapped so that the second SC bank will start its charging process while the first SC bank is now discharging through the load. This way both charging and discharging of SC bank can be done efficiently while charging the battery bank in the system by the same manner.Item Improving the Energy Storage of Standalone PV Systems while Enhancing the Charging Efficiency using Supercapacitors(IEEE Xplore Digital Library, 2019) Piyumal, P.L.A.K.; Ranaweera, A.L.A.K.; Kalingamudali, S.R.D.; Kularatna, N.Usually a battery is used as the energy storage device in typical standalone solar photovoltaic (PV) systems. It is charged by a solar charge controller. The charging efficiency of the system depends on the efficiency of the DC-DC converter of solar charge controller. However, a considerable amount of usable energy is wasted during the charging process. In this work, a method is proposed to utilize this wasted energy and thereby to enhance the charging efficiency. In the case of an empty capacitor being charged by an external source, it stores only half of the energy delivered by the source as compared to that of an electrochemical battery. Therefore, it wastes 50% of useful energy. A portion of this wasted energy can be collected and utilized if a useful resistive load is connected in series to this capacitor charging loop. In this study, a DC-DC converter and battery bank is connected as the useful resistive load in the capacitor charging loop. A supercapacitor (SC) bank is used replacing the conventional capacitor. Therefore, total energy loss in capacitor charging loop can be minimized by storing energy in both battery bank and SC bank. This concept is introduced into a typical PV system for reducing its energy losses. Experimental results show an enhancement in charging efficiency when this new method is employed. The energy stored in the SC bank could be used for driving loads with required electronics.Item Designing and constructing a DC microgrid with uninterrupted power supply capability and optimizing its energy usage by smart controlling system(2018 IEEE International Conference on Industrial Electronics for Sustainable Energy Systems (IESES), 2018) De Zoysa, H.B.H.; Guruge, P.A; Kalingamudali, S.R.D; Kularatna, N.; Kanishka, G.Abstract: This paper outlines the methodology of designing and implementation of a solar powered system which can be used to make a human comfort zone during day time without using battery backup but with the use of Supercapacitors. Basically, major converter losses are reduced in this system. In acquiring a highly efficient power supply, the charge controller plays an important role. When a DC microgrid powers DC loads based on a renewable source such as a PV system; energy storage becomes mandatory due to fluctuating nature of the source. Localized DC-energy storage within DC-DC converters could address this requirement. A variation of supercapacitor assisted regulators could provide localized energy storage with low-noise and fast transient response [1]. 12 V LED lights will be powered from this system. LEDs can be powered directly via a supercapacitor bank from the regulated Photovoltaic energy. In the case of Inverter type Air Conditioner, in order to overcome converter losses, the DC Bus inside it should be accessed. Typically, DC Bus voltage inside the Variable Frequency Drive (VFD) is 1–414 times the supply voltage. Hence DC-DC Converters are used to power up the inside circuitry of the Inverter Air Conditioner from the solar panel. In order to optimize the energy usage and reduce electricity consumption, light dimming and air conditioning control systems were added to control the light intensity and switching of the air conditioner.