# Energy Efficiency Improvement in Reconfigurable Photovoltaic Systems: An Evaluation of Team Systems
## 4 Experimental Setup for Laboratory Tests  
To obtain practical results for the partial validation of the previously exposed theory, a laboratory experimental setup was configured. As mentioned in the previous section, the implementation of MIX systems requires inverters with the capability to operate effectively in parallel, which are not readily available on the market. For this reason, it has not been possible to implement this type of system to validate its operation. The case of team systems is different because they can be implemented using commercial grid-connected inverters and controlled switches, such as electromagnetic switches or relays. The implemented experimental setup used for the characterization of CGPV systems based on the team concept is shown in Figure 7. A system that uses only two photovoltaic generators (\(n=2\)) is implemented, because this configuration is the one that results in the greatest increase in the annual energy efficiency (\(0.71\%\) increase). The two PV generators are emulated by two solar array simulators (SAS). These instruments operate as programmable PV arrays using the GPIB interface and allow the repeatability of different tests in the same irradiance and temperature conditions. The two SAS used are the model E4362A mounted in the mainframe E4360A, all of them manufactured by Keysight (Santa Rosa, CA, USA). Each SAS has \(600\) W of maximum power and can be configured as a PV array with \(130\) V as the maximum open-circuit voltage and \(5\) A as the short-circuit current. The two used inverters (INV) are the model Sunny Boy SB700 manufactured by SMA Solar (Niestetal, Germany) and they are configured with \(P_{INV}=460\) W as the rated output power. Each inverter is connected to the grid through an energy meter (EM) model EM111 DINAV81 XS1X manufactured by [PERSON] (Steinhausen, Switzerland). This  
Figure 6: Relationship between annual energy efficiency (\(\eta_{E}\)) and the number of basic PV generators (\(n\)) used in a team-based GCPV system of up to \(n=8\). energy meter can measure bidirectional power in 230 V grids with current up to 45 A and incorporates a communication port based on the RS485 Modbus protocol. The system controller is based on the Arduino UNO, manufactured by Arduino SA (Chiasso, Switzerland), as a general-purpose programmable platform. This controller monitors the inverter's output power and, in accordance with Equation (9), sends the order to group or divide the PV arrays. The switch used in the system is based on an electromagnetic relay implemented in the D1 Mini Reay Shield, manufactured by HiLetgo (Shenzhen, China), this device is compatible with the products of the Arduino SA family. The whole operation of the system is supervised by a personal computer (PC). The PC sets the emulation steps by programming the I-V characteristic curve in each SAS and records the power values in the inverter's input and output. The power at the inverter's output, measured by the EM, is obtained by the Arduino UNO controller and sent to the PC for recording purposes. The I-V characteristic curve is programmed (using MATLAB 2022a) in SAS by PC using four values (the equivalent of three working points): short-circuit current, open-circuit voltage, and current and voltage at the maximum power point. These values are obtained from irradiance and temperature data and a mathematical model of the PV array. The PC also communicates with the SAS to obtain the power at the inverter's input and record these values. The duration of each emulation step is set to 1 s, the same time interval between data in the irradiance and ambient temperature series used. This small step allows the emulation of the tested PV systems in real-time and captures the real slow dynamic behavior of the PV inverters used. The drawback that appears is the long time necessary to perform an emulation, which is almost 14 h because the data series used have more than 50,000 irradiance and temperature values.