Techno-economic analysis of a hybrid solar PV-grid powered air-conditioner for daytime office use in hot humid climates – A case study in Kumasi city, Ghana

Abstract

Air-conditioners are the highest energy consuming appliances in the offices of businesses, public and commercial buildings in hot humid climates. In Ghana, survey conducted indicates that 60–80% of electricity used in offices of public and commercial buildings is for air-conditioning. Many hot climates, and Ghana in particular, are endowed with high solar irradiations. The need for daytime office space cooling is actually as a result of high solar radiation levels.In the present work, studies have been conducted on the performance of a hybrid solar PV-grid powered air-conditioner for daytime office cooling in hot humid climates with a case study in Kumasi city, Ghana. A standard office of 30 m2 floor area (105 m3 office space) in a building with three of the sides sharing walls with adjacent offices, and the front side facing north was used for the study, with the air-conditioner set at a temperature of 20 °C. In the experiment, the pure sine wave hybrid inverter with integrated PWM charge control system was set to solar energy priority and supported by utility grid electricity when solar energy is not sufficient.It has been determined that for daytime office cooling, a 1040 Wp solar PV system with 200 Ah, 24 V battery configuration has a monthly mean solar fraction of 51% ± 9% for an air-conditioner with nominal cooling capacity of 2.5 kW and maximum power consumption of around 1.19 kW. The energy generation of the 1040 Wp solar PV system has been determined to be around 1211 kWh per year. Financial analysis has revealed that for the hybrid solar PV-grid powered air-conditioner, there is potential savings of US$ 1600 compared to 100% utility grid electricity in 10 years. It has also been estimated using available data that there is a potential of about US$ 3300 savings when the air-conditioner is powered with 100% solar energy compared to 100% utility grid electricity in 10 years, for daytime office use.