Abstract:
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.
