Patent Application
20110168240
This disclosure relates to solar cells, and more particularly to a cover for solar cells.
Solar panels have been used to generate electricity from light. Solar panels include a plurality of individual solar cells, also known as “photovoltaic cells.” Solar cells have been used on roofs of buildings, in part because that a rooftop location provides maximum exposure to sunlight, and in part because the unsightly appearance of solar cells would widely be considered unacceptable within a building such as a home or office. Concealing a solar cell for indoor use has previously not been feasible due to the severe decrease in efficiency that would occur if a solar cell was concealed.
An energy harvesting system includes at least one solar cell operable to harvest solar energy, and a translucent cover concealing the solar cell. The translucent cover exhibits a haze of at least 80% and a light transmission efficiency of at least 70%.
A method of harvesting solar energy includes securing at least one solar cell to a support member, concealing the at least one solar cell with a translucent cover, and harvesting solar energy from light passing through the translucent cover. The translucent cover exhibits a haze of at least 80% and a light transmission efficiency of at least 70%.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
a illustrates an energy harvesting system including at least one solar cell concealed by a translucent cover.
b illustrates another view of the energy harvesting system of
a illustrates an implementation of the energy harvesting system of
b illustrates another view of the energy harvesting system of
a-b illustrates an energy harvesting system 10 that includes at least one solar cell 12 concealed by a translucent cover 14. As shown in
There are competing objectives for the translucent cover 14, as a maximum amount of light efficiency is desired to allow the at least one solar cell 12 to operate efficiently, and at maximum amount of light diffusion is desired to obscure the at least one solar cell 12 so as to hide its appearance beneath the translucent cover 14. Concealing the solar cell 12 with conventional materials such as perforated metals, sheer fabrics, and semi-transparent plastics could conceal the solar cell 12. However, by doing so the efficiency of the solar cell 12 would be significantly reduced in direct proportion to the amount of available light, rendering the solar cell largely ineffective. One could feasibly compensate for this loss in efficiency tends by making the solar cell 12 and its cover 14 larger, however this would be a very costly solution.
To address the conflicting needs for diffusion and light transmission efficiency, the translucent cover 14 is composed of a material exhibiting a haze of at least 80% and a light transmission efficiency of at least 70% such that the translucent cover 14 diffuses light to conceal the solar cell 12, but still enables the solar cell 12 to collect a sufficient amount of light to power a load. Example materials exhibiting these properties include Makrolon® 2407-021065, Makrolon® 2407-021066, Makrolon® 2407-021067, Makrolon® 2407-021068, RTP 1899 X 114729 SC26696, or RTP 1899 X 114729 SC26697. Of course, other materials could be used.
The ASTM D1003 “Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics” defines “haze” as “(1) in transmission, the scattering of light by a specimen responsible for the reduction in contrast of objects viewed through it; (2) the percent of transmitted light that is scattered so that its direction deviates more than a specified angle from the direction of the incident beam.” ASTM D1003 also outlines methods for testing the haze of a material.
Light transmission efficiency may be measured by using a device, such as a luxmeter, to measure an amount of light on a first side of the cover 14, and to measure an amount of light on a second side of the cover 14, and by comparing those amounts. Thus, if there were 100 lumens on a first side of the cover, and 85 lumens on a second side of the cover, the cover 14 would reduce light by 15%, and would have a light transmission efficiency of 85%.
a-b illustrate a translucent cover 28 for the energy harvesting system 10 of
As shown in
By effectively concealing the solar cells 12, 22, the translucent cover 14, 28 is able to provide an aesthetic effect that was unavailable until now, and is able to provide a protective feature to prevent objects from contacting the solar cells 12, 22, while simultaneously permitting a sufficient quantity of diffuse light to reach the solar cells 12, 22 to enable those solar cells to power their respective loads. This enables the solar cells to be contained within aesthetically pleasing decorative components of a living space, and could lead to a great expansion of the use of solar cells within homes, and not merely on rooftops as they have historically been used.
Although the load of the solar cells 22 has been described as a motion sensor 24 and an RF transmitter 26, it is understood that these are only examples, and that many other types of loads could be powered by a solar cell concealed by a translucent cover having the described properties of exhibiting a haze of at least 80% and a light transmission efficiency of at least 70%.
Although embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
