Technology

High Efficiency Design to Produce 200% of the Power Output of Conventional Solar Cells

Revolutionary Design Our revolutionary 3-dimensional silicon solar cell is designed to maximize the conversion of sunlight into electricity. We have developed two breakthrough features in our single wafer silicon solar cell that we believe will deliver benefits that have eluded the solar industry to date.
  • High Efficiency – Our innovative solar cell technology utilizes a 3-dimensional design to increase the conversion efficiency by trapping sunlight inside photovoltaic micro-structures where photons bounce around until they are converted into electrons.
  • Wide Angle Light Collection - Our solar cell has a special wide angle feature on the surface to capture more light in the morning and evening hours, as well as in the winter months when the sun is not directly overhead.
We estimate that our patent-pending 3-dimensional cell can produce 200% of the power output of conventional solar cells. This will reduce the investment payback period of solar panel systems by more than 40%. The graph on the right compares our projected efficiency with a conventional solar cell across a range of incident sun angles.

Wide Angle Light Collection Conventional solar cells become dramatically less efficient if the sun is not shining within a narrow range of incident angles. Sunlight that hits the cell outside of this range will be reflected off, and the reduced light energy causes the cell's internal efficiency to drop. Because of a unique wide angle design, our solar cell can maintain its high efficiency over a wider range of incident angles. It can capture more light in the morning and evening hours, as well as in the winter months when the sun is not directly overhead.

The key to this breakthrough is a special design on the cell surface that collects sunlight over a wide range of angles. The collected light is then forced into 3-dimensional photovoltaic micro-structures beneath the cell surface that trap the light and convert it into electricity. As the sun moves across the sky, throughout the day or year, the Solar3D cell will be able to maintain its high conversion efficiency, as if the sun was directly above it.

High Efficiency Solar cell efficiency is the measure of how much incident sunlight is converted into electricity. Most solar cells today are made from silicon, an inexpensive and abundant raw material. Due to the physics of silicon, the theoretical maximum efficiency of high-grade crystalline silicon solar cells is approximately 29%. In commercial practice, the efficiency ranges from 15% to 19%.(1) Our 3D solar cell is calculated to have an internal efficiency of 25.47%, more than any existing silicon solar cell, and is designed to take advantage of low cost manufacturing processes.

The Problem – Light Reflection and Electron Loss
Conventional solar cells are 2-dimensional, utilizing a single pass sunlight conversion mechanism. There are two primary ways that these devices lose light and electrons, or electron-hole pairs, which result in a conversion efficiency much less than the theoretical maximum.
  • Surface Reflection – Due to fundamental physics, approximately 30% of incident sunlight is reflected off the surface of silicon cells.
  • Electron Re-absorption – When a photon strikes the solar cell, an electron is “knocked loose” creating an electron-hole pair that moves through the cell material, creating electrical current. However, in conventional 2-dimensional solar cell designs, these electron-hole pairs must travel a long distance before reaching a metal contact wire. As a result, they are reabsorbed by the material and do not contribute to the production of electrical current.
  • Morning, Evening and Winter Light Loss – Conventional solar cells reach their quoted efficiencies of 15%-19% only when the incident sunlight is within its narrow acceptable angle. During morning and evening hours, and winter days, the sun is shining from outside of this angle. As a result of the reduced flux in solar energy during these times, the operating efficiency of conventional solar cell is often below its quoted number.
The Solution – 3D Light Trapping and Electron Extraction
Solar3D’s 3–dimensional solar cell is designed from the ground up to optimally reduce all primary losses to achieve the highest conversion efficiency. By leveraging the high volume scalability of conventional solar and semiconductor processes, we believe our 3D solar cell can deliver an unprecedented low total cost of ownership for any given solar installation. Unlike conventional solar cells where sunlight passes through one time, our 3D solar cell design traps sunlight inside photovoltaic structures where photons bounce around until they are all converted into electricity. The key features and benefits of our 3D solar cell design are:
  • Wide Angle Light Collection – Instead of allowing sunlight to bounce off the surface, our unique wide angle light collection feature is engineered to capture light from a wider range of angles Š including morning, evening and winter angles – and guides all incident sunlight into a subsurface micro–photovoltaic structure.
  • 3D Photovoltaic Structure – Conventional solar cells have only one photon absorbing surface. We use a multi-facetted 3D photovoltaic structure where photons can bounce off many surfaces until all photons that can be absorbed by the material are absorbed.
  • Thin Absorbing Regions – Our 3D photovoltaic structure will be fabricated with very thin absorbing regions and designed to enhance charge carrier separation. Therefore, electron-hole pairs will travel short distances before reaching a contact wire where they will be quickly extracted to produce current. This approach also leads to an overall height and silicon material reduction when compared to conventional crystalline silicon cells.
  • Below Surface Contacts – Unlike conventional solar cells where electrical contact wires run on the top of the cell, blocking sunlight, our design uses a network of contact wires that run below the light collectors. This approach allows our 3D solar cells to trap and utilize nearly 100% of the incident light.
An Extraordinary New Solar Cell Solar panels using Solar3D cells can be installed on smaller surface areas, due to our 3D cell’s high efficiency and high power output features. Solar panels using Solar3D cells will not need tracking systems that follow the sun to maintain high efficiency because of its wide angle light collection feature. Solar panels using Solar3D cells can be installed flat on surfaces that do not face the sun directly, eliminating the need for unsightly mounting structures.

From solar farms, to rooftops, to mobile devices, to military applications, to consumer products, we believe our Solar3D cell will be the obvious choice for next generation solar panels. We believe we can dramatically lower the Total Cost of Ownership of solar panel systems. Our low cost, high efficiency solar cell also eliminates the need for supporting components such as tracking systems and mounting structures. Our innovative solar technology will make solar cells substantially more useful in substantially more applications.

Beyond Silicon Our initial commercialization objective is to create a low cost, high efficiency silicon solar cell based on our 3D technology. By keeping our focus on silicon, we can leverage the tremendous silicon infrastructure and manufacturing processes of the growing solar industry, as well as the mature and highly optimized semiconductor industry. However, since our focus is on re-engineering the solar cell, our 3D technology is materials agnostic and can be used with other materials for use in concentrated solar and high performance applications.

(1)Solar Cell