Big Solar Limited. A development project for high yield transparent conductor free solar cell manufacture Target pilot delivery is <0.

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1 Roll to roll microgroove photovoltaic devices Big Solar Limited A development project for high yield transparent conductor free solar cell manufacture Target pilot delivery is <0.2 GBP per Watt john@powerroll.solar

2 Built In Groove Concept Grooves produce cells cascaded serially

3 USP Of Groove Device LCOE 50% cheaper than Si and comparable with fossil fuels with 1 product replacement at year 10 Mass per unit power Ease of deployment and reduction inbalance of system costs Production yield simple four step manufacturing process using known processes The increased connectivity increases robustness Resistance to new developments Any material developments can be considered

4 Process Overview Base flexible substrate Using any type of flexible substrate as a fabrication precursor

5 Cast and emboss a structure The requirements of the structure are that it has an aspect ratio high enough for shadowing to occur

6 Using selective vacuum coating for a first layer The first layer follows the structure and extends out toward the direction of the coating source

7 Further selective coating of the second layer The structured coating connects at the top of the features but remains normally open at the bottom of the structure. This reduced the possibility of short circuit failure increasing the process yield and allowing high speed manufacture

8 Cavity filled with a continuous coating Further circuit connections are made at the ends of the structured areas where the individual cavity voltages are summed reducing the coat weight of conductor required

9 Interconnection Strategy Maximum working surface area is required for highest yield embodiments. Further groove patterns have been used to achieve this parallel connection

10 Semiconductor Absorber Vacuum coating had shown a working system True skunk works + much luck Access to Absorber inks required Collaborations sought -present colaborations include University of Sheffield University of Texas Austin Oxford university Centre for Process innovation Loughborough University Results indicate a viable process

11 Initial Vacuum Coating Using a rotating drum and thermal deposition multiple layers combinations were coated Leading and trailing edges of the structure are coated separately being on separate sides of the drum

12 Organic Results [Sheffield] P3HT/PCBM cell Groove cross section Produced with a bell jar coater onto very poorly defines 300nm grooves, target groove depth 300nm

13 NGPV at the UTA Next Generation PhotoVoltaic program Led by:-prof Brian Korgel at University of texas Austin Excellent for our development needs Metrology, absorber expertise, willing collaborators Multiple feedback and optimization iterations Not an easy process Architecture verified Proof of architecture phase completed Relative performance

14 NGPV results after many iterations 1.5u grooves coated Al,CdS,---,Au UTA fabricated CIS ink ultrasonic spray deposited Lead UTA researcher PhD Candidate Doug Pernik Thank You Doug!

15 What did the UTA result mean Standard flat cell fabrication Max PCE flat cell over course of study 2.7% Groove cell fabrication Max PCE over course of study +3% Simplified construction fewer steps Vacuum coating plus absorber spraying works Samples being shipped back and forth Technology secured next round investment

16 Emerson and Renwick web coater Improved Facilities Double drum coat ebeam Web Coating uniformity Low Material limitations UK ink synthesis Delay times removed UK absorber coating CPI project In house R2R coater

17 Perovskite in grooves Using grooves not optimised for perovskites Simple spin coating in air

18 Ongoing Development Activities Barrier coatings Currently looking at three absorber systems CIS PbS Perovskite Proving: architecture longevity fabrication Current phase target 7% R2R cascades Verify low cost model Verify longevity

19 Summary / next steps Proven technology at lab scale deposition Multiple absorber pathways Collaboration routes Stack integration Exemplars

20 The End? The grooves work Proof of concept completed All materials and components low cost Excepting the semiconductor absorber High throughput vacuum coating possible Moving to small scale R2R trials Much to do but multiple pathways established Seeking appropriate collaborations Target market ready product 2018