Outdoor Performance Test of Bifacial n-Type Silicon Photovoltaic Modules

Sanghwan Park,Hyeonwook Park,Sungho Chang,Woo Kyoung Kim

doi:10.3390/su11226234

Abstract

The outdoor performance of n-type bifacial Si photovoltaic (PV) modules and string systems was evaluated for two different albedo (ground reflection) conditions, i.e., 21% and 79%. Both monofacial and bifacial silicon PV modules were prepared using n-type bifacial Si passivated emitter rear totally diffused cells with multi-wire busbar incorporated with a white and transparent back-sheet, respectively. In the first set of tests, the power production of the bifacial PV string system was compared with the monofacial PV string system installed on a grey concrete floor with an albedo of ~21% for approximately one year (June 2016–May 2017). In the second test, the gain of the bifacial PV string system installed on the white membrane floor with an albedo of ~79% was evaluated for approximately ten months (November 2016–August 2017). During the second test, the power production by an equivalent monofacial module installed on a horizontal solar tracker was also monitored. The gain was estimated by comparing the energy yield of the bifacial PV module with that of the monofacial module. For the 1.5 kW PV string systems with a 30° tilt angle to the south and 21% ground albedo, the year-wide average bifacial gain was determined to be 10.5%. An increase of the ground albedo to 79% improved the bifacial gain to 33.3%. During the same period, the horizontal single-axis tracker yielded an energy gain of 15.8%.

Highlights

The enhancement of power production by utilizing bifacial photovoltaic (PV) modules and systems is known to be one of the most promising approaches, and their market is expected to expand tremendously [1]
A global analysis and optimization of various bifacial module configurations using opto-electro-thermal simulations suggest that a bifacial gain of nearly 30% can be achieved under the conditions of a module height of 1 m and an albedo of 50% [2]
The results of outdoor tests indicate a bifacial gain in excess of 20% for a bifacial module (72-solar cells) that is south-oriented at an installation angle of 30◦ and ground albedo of ~50% [3]

Summary

Introduction

The enhancement of power production by utilizing bifacial photovoltaic (PV) modules and systems is known to be one of the most promising approaches, and their market is expected to expand tremendously [1]. N-type single crystalline silicon PV cells are known to have higher short-circuit current (ISC), open-circuit voltage (VOC), and fill factor (FF) compared to p-type cells, and have advantages in terms of the commercialization of high-performance PV cells and modules. They are relatively stable against light-induced degradation (LID) and are less sensitive to impurities within the silicon materials [9]. The bifacial PV gain was compared to that of a horizontal single-axis tracker

Materials and Methods

Findings

79 Single module