Photovoltaic Cell Module And Method Of Forming Same

Abstract

A photovoltaic cell module, a photovoltaic array including at least two modules, and a method of forming the module are provided. The photovoltaic cell module includes a substrate and a tie layer disposed on the substrate. The tie layer has a depth of penetration of from 1.1 to 100 mm and a tack value of less than −0.6 g·sec. The photovoltaic cell module also includes a photovoltaic cell disposed on the tie layer. The method of forming the photovoltaic cell module includes the steps of disposing the tie layer on the substrate and disposing the photovoltaic cell on the tie layer to form the photovoltaic cell module.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The subject patent application claims priority to, and all the benefits of, U.S. Provisional Patent Application Ser. Nos. 61 / 036,748 and 61 / 036,752, both filed on Mar. 14, 2008, and U.S. Provisional Patent Application Ser. No. 61 / 146,551 filed on Jan. 22, 2009. The entirety of these provisional patent applications is expressly incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention generally relates to a photovoltaic cell module and method of forming the same. More specifically, the photovoltaic cell module includes a substrate and a tie layer having particular properties that is disposed on the substrate.DESCRIPTION OF THE RELATED ART[0003]Solar or photovoltaic cells are semiconductor devices used to convert light into electricity. There are two general types of photovoltaic cells, wafers and thin films. Wafers are thin sheets of semiconductor material that are typically formed from casting or mechanically sawi...

AI Technical Summary

Benefits of technology

[0015]The tie layer allows light to enter the photovoltaic cell and be efficiently converted to electricity. The tie layer also allows the photovoltaic cell to be secured within the photovoltaic cell module while simultaneously allowing for trapped air to be evacuated from underneath thereby leading to increased durability and weatherability. The tie layer further allows for cost effective and repeatable production of the photovoltaic cell module because of efficient evacuation of the trapped air.

Problems solved by technology

However, encapsulants and encapsulation methods known in the art are expensive and time consuming and typically ineffective.

Hence, photovoltaic cells including EVA are limited to harvesting light at wavelengths above 400 nm.

More specifically, EVA has low UV resistance, has a tendency to discolor, and has a tendency to chemically and physically degrade upon exposure to light.

EVA is also known to exhibit poor adhesive properties relative to glass substrates and have a high modulus.

These poor adhesive properties and high modulus tend to cause high stress conditions around the photovoltaic cells resulting in gradual delamination of the encapsulant from the substrate.

This delamination leads to water accumulation in the encapsulant and photovoltaic cell corrosion.

However, this reduces a total amount of available light impinging on the photovoltaic cell, thereby reducing cell efficiency.

However, use of the doped glass or UV absorbers typically causes a 1% to 5% loss in photovoltaic cell efficiency.

Production of photovoltaic cells in this way is relatively expensive and time consuming.

This method tends to promote side reactions that reduce overall durability.

If peroxides are used, curing temperatures typically range from 150° C. to 160° C. These temperatures typically cause excessive stress in the photovoltaic cells and result in mechanical breakdown and / or increased production time and a number of steps needed to strengthen the photovoltaic cells.

The glass superstrate (D), whilst transparent to light, is typically doped with cerium and antimony to filter UV light thereby increasing production costs and complexities.

In addition, silicones have been investigated for use as encapsulants but are not typically used due to numerous drawbacks resulting from production methods.

Whilst this method provides significant advantages over other encapsulation methods, the method tends to trap air bubbles underneath the photovoltaic cells which causes the photovoltaic cells to exhibit inferior properties.

Additional drawbacks include a difficulty in controlling thickness of the encapsulant, increased expense, increased processing times, and increased processing complexity.

These all result in increased cost for the end purchaser.

The prior art does not account for differing thicknesses of electrical leads that are included on photovoltaic cells in relation to detrimental exposure of such leads due to long term use of the photovoltaic cells, weathering, and general wear and tear.

The exposure of the leads results in decreased performance and decreased conversion of light into electricity.

Furthermore, the prior art does not account for the use of differing amounts of encapsulants to protect the electrical leads while maintaining performance and decreasing production costs.

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