Near-maximum-power-point-operation (nMPPO) design of photovoltaic power generation system

The present study proposes a PV system design, called “near-maximum power-point-operation” (nMPPO) that can maintain the performance very close to PV system with MPPT (maximum-power-point tracking) but eliminate hardware of the MPPT. The concept of nMPPO is to match the design of battery bank voltage V_set with the MPP (maximum-power point) of the PV module based on an analysis using meteorological data. Three design methods are used in the present study to determine the optimal V_set. The analytical results show that nMPPO is feasible and the optimal V_set falls in the range 13.2–15.0 V for MSX60 PV module. The long-term performance simulation shows that the overall nMPPO efficiency η_nMPPO is higher than 94%. Two outdoor field tests were carried out in the present study to verify the design of nMPPO. The test results for a single PV module (60Wp) indicate that the nMPPO efficiency η_nMPPO is mostly higher than 93% at various PV temperature T_pv. Another long-term field test of 1 kWp PV array using nMPPO shows that the power generation using nMPPO is almost identical with MPPT at various weather conditions and T_pv variation from 24 °C to 70 °C.