# Energy Efficiency Improvement in Reconfigurable Photovoltaic Systems: An Evaluation of Team Systems
## 7 Discussion  
MIX (or Multimaster) and team PV inverters were introduced by some manufacturers in the first decade of the 2000s to improve efficiency when central PV inverters operate under low-load conditions. This expected improvement in efficiency is highlighted in the technical documentation of these inverters, but there have been few published research studies on these topologies.  
The lack of published studies can be understood in the case of MIX inverters due to the complexity of their design since it is based on the parallel operation of several inverters. In this topology, one inverter assumes the role of the leader device, and the remaining inverters are considered follower devices. Only the leader inverter implements an MPPT algorithm of the PVG, and the control of the MIX system must guarantee the correct distribution of energy between all inverters operating in parallel.  
This topology is impossible to implement using conventional PV inverters because they must operate in a coordinated way, thus increasing the control complexity.  
On the other hand, the lack of publications related to the team topology is less expected, since it can be implemented using conventional and commercial PV inverters. In this case, all active inverters have to implement an MPPT algorithm, and the power flow between the active PV inverters is directed using controlled switches.  
In any case, the simulations performed of these two topologies of reconfigurable PV systems confirm that they have greater energy efficiency than those based on non-reconfigurable topologies. Furthermore, the tests carried out in this work on a PV system based on a team topology also confirm the higher energy efficiency initially assumed. In this regard, Table 6 presents an overview of results obtained from the emulations performed in this work.  
According to the data obtained, days with low irradiance levels (always lower than the reconfiguration power threshold value) demonstrate greater increases in energy production when the reconfigurable system is considered.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & **Sunny Day** & **Cloudy Day** & **Partly Sunny Day** \\ \hline Increment of energy & & & \\ (Wh/day) & 14.47 & 88.80 & 77.23 \\ Energy gain & 0.3\% & 21.6\% & 14.0\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Increase in the amount of energy delivered to the grid (absolute value) and energy gain (expressed in percentage).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Energy by** & **Energy by** & **Total** & **Switching** \\  & **First Inverter** & **Second Inverter** & **Energy** & **Energy Losses** \\  & **(Wh/Day)** & **(Wh/Day)** & **(Wh/Day)** & **(Wh/Switching)** \\ \hline Fixed system & 272.00 & 279.58 & 551.58 & - \\ Team system & 546.45 & 82.36 & 628.81 & 2.10 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Energy comparison between the two examined system.  
Based on the tests carried out and the data obtained, it is practically impossible to make an accurate estimate of the increase in energy efficiency that can be obtained during one year if reconfigurable PV systems are used.  
To perform this estimation, it would be necessary, among others, to have information on the daily weather in the considered location, and a representative irradiance profile should also be defined for each possible type of day. These issues define future lines of research in the field of reconfigurable photovoltaic systems, and they will be addressed in the future.