Barrier films and high throughput manufacturing processes for photovoltaic devices

Abstract

Methods and devices are provided for improved roofing devices. In one embodiment of the present invention, a photovoltaic roofing assembly is provided that comprises of a roofing membrane and a plurality of photovoltaic cells supported by the roofing membrane. The photovoltaic cells may be lightweight, flexible cells formed on a lightweight foil and disposed as a layer on top of the roofing membrane. The roofing assembly may include at least one flexible encapsulant film that protects the plurality of photovoltaic cells from environmental exposure damage, wherein the encapsulant film is formed using a non-vacuum process. Optionally, the process may be a lamination process. In other embodiments, the process is a non-vacuum, non-lamination process. The resulting roofing membrane and the photovoltaic cells are constructed to be rolled up in lengths suitable for being transported to a building site for unrolling and being affixed to a roof structure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This patent application is a continuation of U.S. patent application Ser. No. 11 / 746,799 filed May 10, 2007 which claims the benefit of priority to commonly assigned, copending U.S. Provisional Application Ser. No. 60 / 746,626 and 60 / 746,629 both filed May 5, 2006; commonly assigned, copending U.S. Provisional Application Ser. No. 60 / 746,961 filed May 10, 2006; commonly assigned, copending U.S. Provisional Application Ser. No. 60 / 804,570 filed Jun. 12, 2006; commonly assigned, copending U.S. Provisional Application Ser. No. 60 / 804,571 filed Jun. 12, 2006; and commonly assigned, copending U.S. Provisional Application Ser. No. 60 / 806,096 filed Jun. 28, 2006. This application is also a continuation-in-part of copending U.S. patent application Ser. No. 11 / 460,613, 11 / 460,617, 11 / 460,618, and 11 / 460,620 all filed one Jul. 27, 2006. This application is also a continuation-in-part of copending U.S. patent application Ser. No. 11 / 462,360 filed Aug...

AI Technical Summary

Benefits of technology

"The present invention provides a solution for incorporating lightweight, flexible solar cells into roofing assemblies such as roofing membranes. The invention uses a non-vacuum process to create an encapsulant barrier layer that protects the photovoltaic cells from environmental exposure damage. The encapsulant film is made up of a plurality of nanolaminate layers that create a tortuous path for contaminants to prevent them from reaching the photovoltaic cells. The invention also includes a high throughput manufacturing method for producing the roofing assembly. Overall, the invention improves the durability and efficiency of solar roofing assemblies."

Problems solved by technology

These electronic devices have been traditionally fabricated using silicon (Si) as a light-absorbing, semiconducting material in a relatively expensive production process.

Although these thin-film based solar cells are known devices, it remains a challenge to cost-effectively produce these cells in sufficient volume with efficiencies greater than or equivalent to their silicon-based counterparts.

Drawbacks associated with these rigid cells, however, make them suboptimal choices for applications that require lightweight and / or flexible devices.

Furthermore, even if such flexible device were efficiently produced, the types of protective encapsulant materials available today are not well suited for use with such flexible solar cells.

However, as discussed above, it is also is heavy, expensive, rigid, and fragile.

However, polymers have poorer barrier qualities and may be permeable to small molecule gases such as water and oxygen.

Polymers may also be difficult to seal to each other at the edges so that gas intrusion is prevented along the plane of a lamination, and many of them are photochemically reactive and degrade in either flexibility or clarity, or both, by ultraviolet exposure over a period of years or even less.

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