: an innovative CPV solution L’INNOVAZIONE TECNOLOGICA NELLA PRODUZIONE NAZIONALE DI SISTEMI E COMPONENTI LOW- E HIGH-CPV. ® : an innovative CPV solution in cooperation with

Motivations [1] Why «Concentrated PV»? Traditional photo-voltaics based on silicon solar cells needs large sensitive areas due to its rather low (~14%) efficiency Moreover silicon solar cells have (– 0,2÷0,4 %/K) large dependence on temperature: a problem in very hot climates

Motivations [2] The use of high efficiency (~40%) triple junction (3J) solar cells allows for more compact modules 3J solar cells have lower (– 0,04 %/K) temperature dependence: a great advantage in hot climates TwinFocus® original design allows industrialization through reliable and mature technologies already successfully used in automotive industry (largely using recycled and recyclable plastic, aluminum, and glass)

TwinFocus® uses well known triple junction Solar Cells A series of three junctions, each one sensitive to a different spectral range

Funding and manpower of the R&D program Padova University 81,000€ 2007-8 WP3 in the frame of Polo Fotovoltaico (joint program of Regional Government and Padova University with global value 3M€), 253,000€ 2011-2013 Centro Fermi ~80,000€ 2008-2012 Regional Fellowships plus 4 years of junior grant from Centro Fermi Strong and effective industrial cooperation

TwinFocus® uses non-imaging optics and off-axis reflectors .25 .50 cm 250X 500X solar cell Secondary optics Very uniform irradiation profile on cell extremely critical for thermal budget

TwinFocus® implementation Patent pending (PCT/IB2011/054484) - Area of mirrors: 22x18x14 cm3 - Area cell 0.3 cm2 (x2) - Geometrical concentration: ~580 X Refractive or reflective secondary optics: -Savosil: low temperature molded quartz -polished metal cones

TwinFocus® uses passive heat sink Tcell=85 oC @ Tair =35 oC Thermal budget at 600 Suns: 13W

AtemEnergia srl is a Spin-Off company AtemEnergia srl is a Spin-Off company* of the University of Padua, Italy. It was authorized in July, 2010. The experience of the founders was matured in different fields of Experimental Physics in Italy (LNL,LNGS, Centro Fermi) and abroad (CERN, FermiLab) and in very advanced automotive industry (Unitek). Mission of AtemEnergia is the development of advanced technologies for renewable energies, solar CPV in particular, and other high tech products. * University holds 5% stock ownership

Thanks to mature industrial technologies provided by: Mold design Optical polishing Thermoplastic molding

has been realized ® Field measurement in a working tracker for test

TwinFocus® field measurements Typical efficiency is 24%. Data collected with Sun exposure. Haze effect id visible in the second part of the day.

CARATTERIZZAZIONE DI CELLE SOLARI MEDIANTE LUCE DI ELETTROLUMINESCENZA Una cella fotovoltaica in cui viene iniettata corrente elettrica( Jinj) emette luce (elettroluminescenza, EL) analogamente ad un LED Jinj Lo spettro di elettroluminescenza di una cella a tripla giunzione (3J) mostra tre picchi relativi alle tre band-gap delle giunzioni L’intensità dei picchi di EL delle tre sub-giunzioni in funzione di Jinj cresce esponenzialmente La conversione di energia radiante in energia elettrica e viceversa è descritta da un’unica relazione, detta di “reciprocità” (RR); la grandezza che quantifica il fenomeno è la Quantum Efficiency

La luce di EL emessa da una cella 3J di efficienza nota Jpv La luce di EL emessa da una cella 3J di efficienza nota può essere raccolta da un cella da testare ed essere riconvertita in corrente/tensione. PV LED Jinj Voc L’efficienza di riconversione viene determinata dalla misura della tensione di circuito aperto (Voc) della cella pv. PV LED Jinj Voc della cella pv in funzione di Jinj della cella LED presenta un andamento legato al funzionamento combinato delle tre sub-giunzioni Questo tipo di studio costituisce una affidabile e maneggevole procedura per testare le performances delle tre sub-giunzioni di una cella 3J.

Measured power 320W. Weight: 95kg all included. 40 TwinFocus® reflectors will be assembled in a rigid frame 1m x 2m x 0,14m. Measured power 320W. Weight: 95kg all included. Prototype frame during assembly on tracker

Quasi-industrial production line

Six pre-industrial prototypes, high precision low profile trackers under construction : ~30m2, 5,2kWp

A demonstrator of this system is now acquiring data A demonstrator of this system is now acquiring data. The project of this first version of TwinFocus® has been completed and a lot of effort is now spent to develop an even cheaper and more efficient CPV system. Next step will be an XR (reflective and refractive) optics with a concentrating factor near to 1000X, a more homogeneous illumination profile of the solar cell, and a lighter and more efficient heat sink .