RTD 2013SHINE

Self-tracking solar concentration

1EPFL, 2EMPA, 3CSEM

Christophe Moser1, Demetri Psaltis1, Sophia Haussener1,Artur Braun2, Julien Bailat3

Based on a phase-change actuator, a scalable prototype was assembled. The device showed a concentration factor of 3.5x (16° acceptance angle) .

Solar concentrators can play a key role in solar-driven hydrogen generation, resulting in . Avoiding the power consumption of a me-

hydrogen cost, system’s energy and green-house gases balances .

The concentrator’s optical system captures sunlight within a certain an-

the actuator. For a static device, 45° is the recommended minimum accept-ance angle.

RTD 2013SHINE

Self-tracking solar concentration

1EPFL, 2CSEM

Enrico Chinello, Volker Zagolla, Didier Dominé,Eric Tremblay, Christophe Moser

[1]

[3]

[2]

[4]

[5]

Future studies will improve device scaling, to tailor it according to the desired concentration factor (for sili-con cells, up to 20x).

[1] Rodriguez et al., Design and cost considerations for practical solar-hydrogen generators, En. Env. Science, Issue 12, 2014;[2] Dumortier et al., Design guidelines for concentrated photo-electrochemical water splitting devices based on energy and greenhouse gas yield ratios, En. Env. Science, vol. 8, 2015;[3] Zagolla et al., Proof of principle demonstration of a self-tracking concentrator, Optics Express, vol.22, 2014;[4] Zagolla et al., , vol.20, 2012;[5] Zagolla et al., Self-tracking solar concentrator with an acceptance angle of 32°, Optics Express, vol.22, 2014.

The concentrator responds to sun-light actuating a coupling element. The principle of using the thermal expansion of a phase-change materi-al has been demonstrated .

Alternatively, the exploitation of bubble as coupling element has been validated .

pn

H O

H O

H O

H O

H O

H O

H O

H O

(gas)(gas)

H+

4e

4e

H O (gas)N (gas)

H O (gas)N (gas)

H O (gas)N (gas)

H O (gas)N (gas)

2 4H + 4+4H + 4 2H+

hv4e

Light

Glass slab waveguide

Concentrator adaptive coupling layer (IR heated)H N

Lens Array

Sunlight

PEC

Catalyst coated onpro

Thin conducting “foam” porousto conduct electrons & bringwater to the catalyst

H O (gas) + N (gas)