SIZING AND COST ANALYSIS OF SOLAR PV PANEL ARRAYS FOR AN OFF-GRID DC - AIR CONDITIONER FOR A TESTING FACILITY AT MANGOSUTHU UNIVERSITY OF TECHNOLOGY (SOUTH AFRICA)

In this journal paper, the sizing, selection, and cost analysis of a 100-percent off-grid DC-powered air conditioning (AC) system were investigated. The AC system was combined with a photovol taic (PV) system which incorporated solar PV panels (modules), a charge controller, a DC/AC converter (solar inverter), and deep cycle batteries. Now solar power is essential to operate or power the AC system and it can be utilized in regions where there i s zero electricity.The first step in the investigation involved estimating the load due to cooling for the designated area and this was established to bealmost 1-ton refrigeration (1.0 TR)or, in other words, a 3.52 kW cooling capacity unit would suffice this requirement.According to past studies, a package-type vapor compression system suffices this requirement. The estimation of the cooling load and the design comfort conditions required for the selected area to be cooled was all based on the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) standards. The cooling load items such as lighting heat gain, occupancy heat gain, infiltration and ventilation heat gain, etc. were all incorporated in the analysis. To power this unit, 6x 335 watts solar panels were required in series connection. The performance coefficient (CoP) of the air conditioning system was computed and found to be 2.7, (this falls in the normal range of 2- 4). The results of the analysis show that 2 x 48 V DC, 150 Ah batteries were required to provide backup power for the system for 8-hour operation, or 6 x48 V DC, 150 Ah batteries for 24-hour operation. The cost analysis showed that the final system was estimated to be approximately R96500 or $ 6829 (USD)to provide for 24-hour operation and 100 % off-grid connection.