Experimental investigation of a photovoltaic solar air conditioning system and comparison with conventional unit in the context of the state of Piaui, Brazil.

• It was shown that PV based air conditioner can save about $700.00 in energy consumption with a payback in 3.7 years. • The COP for the PV based air conditioner is about 2.6 while the COP for conventional unit is 2.9. • The PV based air conditioner is viable in Piaui, Brazil due to high and stable incident solar radiation. • The PV based air conditioner proved to be stable at times of great cooling demand. • The PV based air conditioner can substitute satisfactorily conventional units in hot regions. Globally the building sector is responsible for a big share of electric energy consumption and emissions. To alleviate these impacts it is necessary to improve the energy efficiency besides implementing renewable energy sources for building sector sustainability. PV panels for generating electric energy are most preferred by the sector. In the present study, two similar rooms were prepared one with a conventional air conditioner of the window type powered from the grid and the other is powered from PV panels. The heat load was calculated and used to define the conventional air conditioner and also to define the area of photovoltaic solar panels and the associated equipments to install a PV circuit for supplying electric energy to the PV air conditioner. Both rooms were equipped with calibrated instrumentation including thermocouples to measure the temperature distribution in rooms as well as electric energy consumption during the experiments. Ambient temperature, wind speed, temperature in the vicinity of the photovoltaic panels, humidity, solar radiation, voltage, current, flow of energy consumed by the systems were measured and registered by data acquisition system. Experiments were carried out with the systems working simultaneously at pre-defined times. The solar PV-based air conditioner consumed approximately 342 kWh during 30 days of experiments, while the air conditioner connected to the grid, consumed about 330 kWh, which is 5 % less than the solar PV air conditioner confirming that solar PV air conditioner is viable. The COP for the solar-based air conditioner is about 2.6 and the COP for conventional air conditioner is 2.9. The incident solar radiation is high and stable in Teresina, Piauí, Brazil which ensures viability of the solar PV air conditioner. The power supply from CC showed better quality and costs an AC system, and that PV System can save about $700.00 in energy consumption and the payback occurs in 3.7 years. [ABSTRACT FROM AUTHOR]