Electrical and Meteorological Data Acquisition System of a Commercial and Domestic Microgrid for Monitoring PV Parameters  
[PERSON]  
1 Fort Hare Institute of Technology, University of Fort Hare, Alice 5700, South Africa; [EMAIL_ADDRESS] (E.L.M. ); [EMAIL_ADDRESS] (O.  
conditions, DAS can readjust the signals and parameters, so as to suit the new environments [2]. Various components make up the DAS such as data acquisition software, signal processors, sensors, computers, communication link, database and so on [3]. Each of these components should function together to constitute a DAS [3]. Typically, a lot of DAS designs have been established in the literature [4; 5; 6]. Their architectures are based on either simulation or experimental methods. The majority of the simulation presented several ways for assessing the reliability of the solar PV system particularly to the project strategy and the economic perspectives [7; 8]. Nevertheless, the viewpoint in estimating the accuracy of energy is pretty low with the simulation devices as compared to the experimental observations owing to the limited input parameters designated for it [9]. Therefore, the only available choice would be experimental studies. A prototype DAS for an off-grid PV power plant was proposed by [10], the system consists of a personal computer, simulator for PV modules and battery storage. The prototype was used to collect data to find out the execution of the power plant. The operation of PV modules under outdoor weather conditions was also a concern for [11]. To this effect, they designed a low-cost current-voltage (I-V) data acquisition system that was used to characterise seven modules subjected to outdoor weather. They argued that results obtained from their study could be adopted in interrogating and comparing PV ratings under realistic operating conditions. Based on their findings, Voc decreases with an increase in ambient temperature whereas photo-generated current and generated power increases linearly with irradiance. In another development, a simple enclosed system centered on DAS was reported in [12] while a web integrated DAS was discussed in [13]. However, for DAS to be continuously in action, PV power plants should be at the forefront. Thus, the components that accompany the operation of PV power plants include the charge controller (charge regulator or regulator), inverter and battery. The function of a charge controller is to protect the battery without impinging unnecessarily on system efficiency [14]. The charge controller controls the rate at which the batteries are charged (high voltage disconnection) and discharged (low voltage disconnection). Charge controllers are classified into maximum power point tracking (MPPT) and Pulse-Width Modulation (PWM) with respect to operation. The MPPT charge controller, which is commonly used for large-scale power plants, operates with an algorithm based on the exploitation of voltage and current variation due to instantaneous power pulsations [15]. PWM charge controller suitable for domestic PV power production takes into consideration that PV modules do not always give the power output due to weather variation. Hence, the PWM charge controller automatically matches the PV voltage with the battery voltage [16]. As the PV and battery produce DC power, an inverter is required to integrate generated power into the national grid or to power appliance and lighting in a house. An inverter is, therefore, a device that converts generated or supplied DC power from the PV or battery into AC power. PV inverters usually have one or two conversion stages. In a single inverter DC to AC, stage one conversion is commonly used, while stage two is DC to DC conversion. The battery bank provides storage for the generated power during the day for consumption in the absence of the sun (night and overcast sky days). That is the size of the battery is subjective by the capacity of the PV module as well as load.