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Cover glass solutions

Description:

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Space Technology

 

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

 

OBJECTIVE: Improve space-based photovoltaic power generation through alternatives and modifications to space-qualified cover glass and encapsulants that increase insolation capture and conversion efficiencies of integrated photovoltaic cells. Solutions should demonstrate the ability to increase power generation from systems utilizing state-of-practice photovoltaic devices.

 

DESCRIPTION: Space Systems Command (SSC), located at Los Angeles Air Force Base, is responsible for developing, equipping, fielding, and sustaining lethal and resilient space capabilities for warfighters. Historically, SSC requires each mission block to have 3-5% more power. This is critical for the United States to maintain space dominance over its adversaries. Unfortunately, efficiency improvements in III-V solar cells have begun to plateau and obtaining 3-5% more power due exclusively through cell efficiency gains is becoming increasing unlikely. In order to reach the goals set by SSC, increased power generation must come from non-traditional improvement methods, including advances in cover glass technology. Cover glass is critical to protect solar cells from the harsh environment of space in Earth’s orbit. Since it is a necessity to have in the system, finding a way to utilize cover glass beyond just a protective barrier can lead to increased performance in the solar module system. There are several approaches to obtain this goal. First, there has been success in literature in texturing cover glass to improve non-normal incident light transparency. By increasing transparency, more light will reach the solar cell to be converted to useful energy that would otherwise be lost. Second, down-shifting molecules absorb harmful UV photons and convert/reemit them in the visible wavelength. This increases the concentration of useful energy reaching the solar cells while simultaneously decreasing the amount of UV light that can degrade them. Last, there is room for improvement in traditional, chemically applied anti-reflective coatings (ARCs). Wider bandgap, less expensive ARCs is another way to increase the amount of light that reaches the solar cells to increase their total power conversion efficiency. Mitigating losses is becoming crucial to keep up with the demands of the increasing more complex and power-hungry spacecrafts fielded by the U.S. Space Force.

 

PHASE I: Awardee(s) will demonstrate materials capable of increased throughput of photons with wavelengths relevant for state of art photovoltaics for space assets. Approaches should aim to modify or replace space-grade cover glass without impacting the durability and usability of the material in a space environment. Candidate technologies include textured cover glass surfaces, doped cover glass or films capable of wavelength shifting non-useable photons, or high-efficiency, low cost anti-reflective coatings.

 

PHASE II: Awardee(s) will develop and demonstrate higher power generation by integrating space-qualified solar cells to the technology advancements demonstrated in Phase 1. Performance should be tested in relevant parameters to the space environment, including electrical characterization and stress testing. Results should be compared to relevant, state of art PV systems.

 

PHASE III DUAL USE APPLICATIONS: Awardee(s) will develop robust manufacturing method(s) and demonstrate consistency and reliability through statistical process control and relevant characterization. Awardee(s) will develop licensing or partnerships to transition technology to established vendors of space-grade photovoltaics. Awardee(s) will perform relevant qualification and validation testing through flight-like articles to advance TRL from 4 to 6 or higher.

 

REFERENCES:

  1. https://www.nrel.gov/docs/fy01osti/28264.pdf
  2. https://www.sciencedirect.com/science/article/pii/S0038092X23004061
  3. https://ieeexplore.ieee.org/abstract/document/654284
  4. https://www.sciencedirect.com/science/article/abs/pii/S0927024809000762
  5. USSF Power & Energetics CCT Tech Need 857 – Space Photovoltaic Cell and CIC Efficiency;

 

KEYWORDS: cover glass; texturing; down-shifting molecules; anti-reflective coating; reflective loss; space solar; power systems

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