Noise-Scaled Euclidean Distance: A Metric for Maximum Likelihood Estimation of the PV Model Parameters

This article revisits the objective function (or metric) used in the extraction of photovoltaic (PV) model parameters. A theoretical investigation shows that the widely used current distance (CD) metric does not yield the maximum likelihood estimates (MLE) of the model parameters when there is noise in both voltage and current samples. It demonstrates that the Euclidean distance (ED) should be used instead, when the voltage and current noise powers are equal. For the general case, a new noise-scaled Euclidean distance (NSED) metric is proposed as a weighted variation of ED, which is shown to fetch the MLE of the parameters at any noise conditions. This metric requires the noise ratio (i.e., ratio of the two noise variances) as an additional input, which can be estimated by a new noise estimation (NE) method introduced in this study. One application of the new metric is to employ NSED regression as a follow-up step to existing parameter extraction methods toward fine-tuning of their outputs. Results on synthetic and experimental data show that the so-called NSED regression “add-on” improves the accurac

In-depth analysis of single-diode model parameters from manufacturer’s datasheet

The objective of this paper is to determine all the possible combinations of the five parameters of the single-diode model (SDM) of a photovoltaic panel when only the following three important points (remarkable points) of a IeV curve, namely, short circuit, maximum power and open circuit points, are available, usually from manufacturer’s datasheet. In this work, four of the five parameters of the SDM are expressed as explicit functions of the remaining one. Taking advantage of this, the monotony of these functions has been studied and the intervals where the corresponding parameters belong have been determined, that is, the domain of the parameters, in terms exclusively of the remarkable points. Using these functions, a unique SDM solution can be also easily determined if an extra data or equation is available. A possible application of this study is to validate if an extra equation is compatible with the set of equations obtained from the remarkable points. The results presented in this paper have been tested with a database gathering information of 8835 datasheets included in the Energy Commission’s Solar Equipment Lists. Comparisons have also been made with other works which have tried to obtain the SDM parameters only with datasheet information

Quick and Accurate Strategy for Calculating the Solutions of the Photovoltaic Single-Diode Model Equation

The photovoltaic (PV) single-diode model is the most widely used to characterize the behavior of a PV panel because it combines high precision with moderate difficulty. Lots of methods to obtain the model parameters use optimization techniques that require the resolution of the characteristic equation thousands of times; therefore, it is essential to calculate its solutions accurately but also in the shortest possible time. The objective of this article is to describe a new numerical strategy to solve the characteristic equation in a simple, fast and precise way. The main idea is based on a reparameterization of the Lambert equation which is closely related with the infinite power tower, and some well-known bounds of this tower will be used as seeds of numerical methods. This strategy is powerful for certain “small” values of the Lambert W function argument, but it is combined with another re-expression of the Lambert equation for the remaining “large” values. The proposed numerical strategy is so precise in very few iterations that it can be suitably transformed into an explicit formula. The results obtained have been compared with some of the best options in the literature and expexperimental results prove the power of the proposed methodolog

System-on-Chip for Real-Time Satellite Photovoltaic Curves Telemetry

This paper presents a System-on-Chip design for real-time satellites photovoltaic curves telemetry. In these applications, the limitation of memory and communication bandwidth makes quite difficult to store and to transmit the whole characteristic current-voltage (I–V) curve of any solar section in real-time. The proposed solution is based on the real-time calculation of the equivalent singlediode model of the solar section. The single-diode model fits accurately the behavior of any solar panel, so once the parameters are calculated, saved, and transmitted, at any working conditions, that specific curve could be later reproduced. The system is based on a LEON3 32-bit microprocessor core implemented in a Field Programmable Gate Array. The LEON microprocessors were originally designed by the European Space Agency, Paris, France, to be used in space projects where high reliability is required. In addition, in order to design the system as simple and reliable as possible, from all the methods available in the literature to extract the five parameters of the equivalent model, the Oblique Asymptote Method has been chosen for its simplicity and precision. Finally, some experimental results are presented to demonstrate the accuracy of the final system

A comparison ofmethods for the calculation of all the key points of the PV single-diode model including a new algorithm for themaximum power point

A comparison ofmethods for the calculation of all the key points of the PV single-diode model including a new algorithm for themaximum power poin