Design, development and performance studies of a stand-alone residential photovoltaic power system

Abstract

A stand-alone pholovoltaic power system is designed to operate residential appliances such as fluorescent lamp, incandescent light and ceiling fan using standard methods. The total load is estimated for four hours of operation per day. The batte!)' is sized considering different factors that affects battery efficiency to reliably operate the estimated loads during a sequence ofbc1ow average insolation. The minimum battery size is ohL1ined 128Ah @ 1DOhr, 24V. The PV array is sized to operate the load on a daily basis based on average weather conditions using monthly average daily values of solar radiation data for cleven years, The array is sized to proper sizes In order to reliably operate the estimated load in the month of minimum insolation considering different types of powcr losses. The minimum array size is obtained 6 x 47Wp for tilt angles of 10" for the months of April to September and 40° for the months of October to March and azimuthal angles :1:45". After completion of design the system is physically installed as per design at Renewable Energy Research Center, Dhaka University. The operation of the load for different months of the year 1997 and 1998 is monitored in various weather conditions. It is found that the performance of the system is very close to the theoretical design. The charging time of the battery decreases by about 10% when the a7imuthal angle of the array is changed from 0° to :1:45".i.e. the more output power is obtained from the same PV modules. The economics of this system is studied to test its feasibility for remote and rural areas of Bangladesh and to compare renewable generators with non-renewable generators, The life cycle cost ofthcse generators are determined using the method of net present va1uc analysis. It is found that the life cycle cost of this experimental PV system is Tk. 37.00IKWh for one family. The life cycle cost for grid electricity is Tk. 20.00/KWh and Tk. 7.7S/KWh for generation fuel costs ofTk. 6.80IKWh and Tk, 0.47/KWh respectively. For a village 1 kilomcter away from the distribution line this cost becomes Tk. 12S.00/KWh. For petrol generator life cycle cost is obtained to be Tk. SO.OO/KWh at f~el price ofTk. 22.00 per liter. For Diesel generator life cycle cost is found to be Tk, 41.00/KWh at fuel cost of Tie. 15.00 per liter. It is found with reference to Bangladesh that the lifc cycle cost of one unit of energy from PV system is less than that from petrol or diesel generators. It is observed that the life cycle cost of one unit of energy from grid that are I kilometer away from a village is much higher than the cost of energy from a PV system. Thus the usc of PV system in rural villages and remote areas of Bangladesh, where there is no grid electricity is economically feasible.