A test protocol to enable comparative evaluation of maximum power point trackers under both static and dynamic irradiance

Abstract

The effectiveness of maximum power point trackers (MPPTs) is an important factor in the energy harvest economics of a PV system. Inverter manufacturers want to maximize the effectiveness of their MPPTs, and plant developers desire to choose inverters with the highest energy harvest to maximize their return on investment. However, comparing MPPTs against one another is challenging because the most common figure of merit, the MPPT efficiency, depends on the characteristics of the PV array and on the time variation of the irradiance. The commonly reported MPPT efficiency is essentially a static metric that does not translate well to performance under the wide range of real world conditions. To enable meaningful comparisons between MPPTs under both static and dynamic conditions, this paper proposes a standardized irradiance profile for use in determining MPPT efficiency. The proposed irradiance profile is designed to minimize bias in the results, maximize reproducibility, and be easy to use. The irradiance profile, its rationale, and its use are described herein.

Impact of solar radiation on the output power of moving photovoltaic (PV) installations

“…Ropp et al proposed a profile for evaluating the performance of MPPT algorithms. Their test protocol consists of slow ramps, fast ramps, and steady-state conditions [14]. Bründlinger et al also suggested a test sequence for the MPPT techniques where the PV inverter and its efficiency are included into their considerations and evaluations [15].…”

“…The question is how realistic such approaches are if we were to compare them against our measurement data. We obtain, for example for r λ,u , from [14]: for steady-state conditions: r λ,u = 0 W m 2 /s for slow ramps:…”

“…In [14], there are steady-state conditions at 200 W/m 2 , 600 W/m 2 , and 1000 W/m 2 , while in [15] no steady-state conditions are considered. However, in [15], the solar radiation level varies between a minimum and a maximum solar radiation level for n repetitions.…”

“…Naturally, these levels are not constant throughout the day. However, the intermediate level makes the test profile in [14] more practical than the pattern proposed in [15].…”

Maximum Power Point Tracking (MPPT) of Stand-Alone Photovoltaic Systems Based on Synergetic Control

“…However, these methods have some disadvantages. For example, perturb and observe P&O algorithm fails to track the MPP in case of rapid environmental changes, and incremental conductance IC oscillates around the MPP [1][2][3]. Some techniques use look up tables, consequently more memory space is required, like the analytical solution for tracking photovoltaic module MPP used in [4].…”