Performance of a new type of module based on back-contact solar cells

Abstract

Imec has developed a new technology to integrate and interconnect back-contact solar cells into modules, based on embedding cells in silicone on top of a glass substrate. This technology aims at an improved optical performance and reliability (through the use of silicones and low-temperature metallization). One of the additional advantages is that the technology is suitable for integrating very thin cells into modules: whereas standalone interconnection of such fragile thin cells, e. g. tabbing and stringing, would significantly lower the throughput yield due to breakage, the cells are better protected if they are embedded inside silicone. The paper will first elaborate on the process flow, the background and motivation, advantages, drawbacks and limitations, and technical aspects of the developed technology. Then it will present the results of the measurements on the performance of functional solar cells processed into modules using this technology, discussing losses and loss mechanisms. Then, the approach towards determining the reliability of the module will be presented, indicating how imec aims at building up an ageing model, and elaborating the results on the failure mode and effect analysis, modeling, characterization and reliability testing

Crystalline thin‐foil silicon solar cells: where crystalline quality meets thin‐film processing

“…Several proofs of concept of silicone bonding and encapsulation have been demonstrated and are depicted in Figure : on wafers as thin as 40 µm , on 100‐µm‐thin 2 × 2 cm 2 interdigitated back contact (IBC) cells , and on standard metal wrap‐through cells from Photovoltech , each time using silicones from Dow Corning. For the latter case, reliability tests have been carried out to evaluate the silicone encapsulation scheme (cells are interconnected by soldering): 1000 h of damp heat, 200 thermal cycles and 10 humidity freeze cycles according to the specifications in the IEC61215 standard were passed successfully (less than 5% degradation).…”