You are here

Ultra-flexible high efficiency photovoltaics

Description:

TECHNOLOGY AREA(S): Electronics 

OBJECTIVE: This effort seeks to develop / advance the state of the art in ultra-flexible high efficiency photovoltaic (PV) technology such that it can be adapted for use in both Soldier portable and large format (e.g. shelter) applications. Prior efforts in integration of PV with textiles have focused on amorphous silicon (a-Si) thin film commercial off the shelf (COTS) technology due to the inherent lightweight, low cost, and flexibility. While these efforts were successful in improving the manufacturability of that technology, and producing multiple demonstration prototypes ranging in size from man-portable to shelter based items, the power conversion efficiency (PCE) of the a-Si technology at the production module level remains in the mid-single digits. Feedback from military program managers on this technology capability have indicated that PCE is too low, and a higher energy conversion capability is desired. To meet this request, this proposal seeks to evaluate PV technologies that can provide a power conversion efficiency (PCE) that is >10% – threshold (T), >15% – objective (O) during both static, and flexed states. Further, since the military has been traditionally focused on textile based platforms for both expeditionary shelters systems, as well as Soldier borne alternative energy platforms – of special interest are proposed technologies that offer “textile-like” characteristics that such demonstration of flexibility would allow for: - Compound curvature (i.e. simultaneous bending in two axis) without impact to the physical or operational ability of the technology - Single axis 25mm bend radius (T), 10mm bend radius (O) Since any alternative based energy source – in this case ultra-flexible PV – has to directly compete against legacy fossil fuel fired energy sources (e.g. electric generators) for transition to a military program of record where procurement happens, it is imperative that several attributes of the alternative energy source are maximized. These include (but are not limited to), wattage, Power Conversion efficiency (PCE), weight, deployed footprint, stowed footprint, and, of course – cost. Additionally, while manufacturing methodology is not a specific focus area of this topic, PV technologies that leverage an existing commercial manufacturing base as a way to provide both immediate manufacturing capability, while concurrently providing immediate economies of scale to reduce cost – are also of special interest. As a result applicant technologies should be able to demonstrate ability to leverage an existing commercial manufacturing base with minimal (T) or no (O) additional process or material development required. While not specifically requested, PV technologies that allow power production earlier in the day, later in the evening, and is also able to produce power in wavelengths outside the visible spectrum are of special interest due to their ability to provide power over a longer period of time for every diurnal cycle. 

DESCRIPTION: Currently fielded flexible PV technologies are not able to meet a bend radius which approaches the natural drape and inherent flexibility of textiles. This has limited attempts to do direct PV module integration with textiles, and those applications where some level of success has been realized, have resorted to “paneling” or “tiling” to achieve stowage without directly folding or creasing the PV modules themselves. The realization of ultra-flexible high efficiency PV technology would benefit both Soldier portable and Expeditionary Maneuver (e.g. soft shelters) areas of interest by providing an avenue to harvest energy in-situ allowing for extended operational capability without resupply, and do so with a technology that offers more conformal capabilities for deployment and stowage than currently available. As an example, currently fielded Soldier portable PV technologies exhibit the ability to provide: - 120 watt item - 4.5 pounds total weight - 32.74 square foot area when deployed - 392 cubic inches when stowed - Maximum dimension of 14 inches in any one axis when stowed. - See: http://www.powerfilmsolar.com/about/news/?powerfilm_awarded_military_foldable_solar_panel_contract&show=news&newsID=21743 Proposed candidate technologies under this SBIR call should show a clear pathway to meeting the following specifications for a Soldier portable item under a standard solar insolation of 1000w/m2: - Minimum 100 Watt item (more is acceptable provided all other attributes are met) - 24VDC nominal operating voltage - < 3 pounds total weight - Covering no more than a 14.5 square foot area when fully deployed flat - Maximum dimension of 15 inches in any one axis when stowed - Less than or equal to 500 cubic inches of volume when stowed - Intent is for stowage in a rucksack or other areas where available cubic volume is at a premium. As such, packing solutions with no inherent voids are highly preferred. - Very low, or no gloss / glint characteristic - No gloss / glint is strongly preferred. - Inherent multiple color camouflage without the use of a power reducing mask or overlay - This attribute is not required, but is strongly preferred. - Operational with no permanent degradation in ambient temperatures and associated relative humidity for categories ranging in temperature from “Basic Cold” (-25 degrees F) to “Hot-Dry” (120 degrees F). - Temperature and relative humidity per specified categories in Army Regulation (AR) 70-38. Link to document is found in “References” section. - Able to withstand temperature and relative humidity for Storage & Transit categories ranging in temperature from “Severe Cold” (-60 degrees F) to “Hot” (160 degrees F) with no permanent degradation to operational capability upon return to ambient temperatures and relative humidity’s specified in operational bullet above. - Temperature and relative humidity per specified categories in Army Regulation (AR) 70-38. Link to document is found in “References” section 

PHASE I: Investigate processes that will lead to development of a robust working photovoltaic (PV) architecture that could be mass produced and would require minimal (T) or no (O) additional capital equipment expenditures - preferably by leveraging an existing commercial manufacturing base capability. 

PHASE II: Building on successful Phase I efforts, down select and refine the identified processes to produce working prototypes that leverages one or more of the commercial manufacturing bases identified in Phase I. Use of a spiral development model that provides interim working prototypes, and allows for incorporation of feedback from the military user community into the next prototype, is highly preferred. Effort should perform small scale environmental (e.g. thermal, UV, moisture, etc.) and wind induced flutter testing to determine durability of proposed PV technology in large scale format applications (e.g. military shelters, solar shades, etc.). Detailed report(s) on testing with pathways to resolving any identified failure modes are expected. Ability of proposed technology to achieve, or demonstrate a clear pathway to achieving, multiple different colors & patterns within the PV module to achieve inherent camouflage without a significant drop in PCE is highly desirable in Phase II. A cost projection for production quantities of final working PV prototypes (see attributes listed on same below for guidance), is requested as a Phase II deliverable. A "data package" to include production and assembly drawings, a bill of materials, and any source code required for re-creating the final deliverable prototype (see attributes listed on same below for guidance) via a third party is requested as a Phase II deliverable. Prototypes: Working prototypes should ultimately have the following characteristics described in the Phase I detailed technical plan: - Interim prototypes having the following attributes under a standard solar insolation of 1000w/m2: • Minimum 60 Watts output at 24VDC nominal • PCE of >10% (T), >15% (O) • < 4.5 pounds total weight • Less than or equal to 15 square foot area when deployed • Less than or equal to 500 cubic inches of volume when stowed • Maximum dimension of 15 inches in any one axis when stowed • The ability to repeatedly achieve the following with no degradation to electrical performance: • Compound curvature (i.e. simultaneous bending in two axis) without negative impact to the physical or operational capability of the technology • Single axis 12mm bend radius (T), 7mm bend radius (O) - Final working PV prototypes having the following attributes under a standard solar insolation of 1000w/m2: • Minimum 100 Watts output at 24VDC nominal • PCE of >10% (T), >15% (O) • < 3 pounds total weight • Less than or equal to 14.5 square foot area when deployed • Less than or equal to 500 cubic inches of volume when stowed • Maximum dimension of 15 inches in any one axis when stowed • The ability to repeatedly achieve the following with no degradation to electrical performance: • Compound curvature (i.e. simultaneous bending in two axis) without negative impact to the physical or operational capability of the technology • Single axis 12mm bend radius (T), 7mm bend radius (O) • Minimal (T) or no (O) glint / glare when viewed from any angle • Single color (T) or multiple colors & patterns (O) 

PHASE III: As eluded to earlier, expected evaluation / use of the developed ultra-flexible PV will be in both the Soldier borne power, and military shelters area. It is expected that commercial equivalent areas such as recreational outdoors market will be early adopters of successful technology development, Some examples of these potential dual use areas may include large scale commercial awnings for use in austere areas (e.g. national park pavilions), or – if camouflage attributes are achieved - power generation for long endurance concealed field sensor applications such as hunting trail cameras. 

REFERENCES: 

1: Prior NSRDEC call for PV textiles to support austere basecamp energy requirements: http://www.defensemedianetwork.com/stories/u-s-army-seeks-energy-producing-tent-fabrics/

2:  Soldier centric wearable energy harvesting efforts: http://www.benning.army.mil/infantry/magazine/issues/2014/Oct-Mar/pdfs/Sisto.pdf

3:  Power and Energy Strategy White Paper: http://www.arcic.army.mil/app_Documents/ARCIC_WhitePaper_Power-and-Energy-Strategy_01APR2010.pdf

4:  Army Regulation (AR) 70-38, RESEARCH, DEVELOPMENT, TEST, AND EVALUATION OF MATERIEL FOR EXTREME CLIMATIC CONDITIONS: http://www.apd.army.mil/epubs/DR_pubs/DR_a/pdf/web/r70_38.pdf

5:  PowerFilm Solar, "PowerFilm Awarded Military Foldable Solar Panel", dtd April 4th 2016. As mentioned in Description http://www.powerfilmsolar.com/about/news/?powerfilm_awarded_military_foldable_solar_panel_contract&show=news&newsID=21743

CONTACT(S): 

Steven Tucker 

(508) 233-6962 

steven.r.tucker10.civ@mail.mil 

US Flag An Official Website of the United States Government