Advanced PhotovoltaicsIncluding New Materials and Approaches

Increasing desire for renewable energy sources has led to the rapid growth and development of photovoltaic (PV) technologies within the

last few decades. It is estimated that 3,850,000 exajoules (1018 joules) in the form of light is received by the earth per year, and the goal of photovoltaics is to harness this energy for use by converting it to electrical power. Advances in PV technology allow for higher

efficiencies, increasing the viability and the presence of photovoltaics in the world.

Yaroslaw Bagriy and Tyler Denis5/7/14

Outline Definitions Efficiency Materials and Approaches Worldwide Statistics and Applications Advantages and Disadvantages Summary References Key Concepts

Definitions

Photovoltaics Solar radiation to direct electrical current

Generations First – pn junction Second – Thin film Third - Multilayer

Production Deposition Lattice Matching

Nominal Power Watt-peak, Wp

http://www.liv.ac.uk/media/livacuk/renewableenergy/images/pvfig3.gif

Basic pn junction solar cell operation

Efficiency

The efficiency of a solar cell is defined as the ratio of output electrical power to incident optical power. Solar constant: ~1.36 kW/m2

http://www.nrel.gov/ncpv/images/efficiency_chart.jpg

Multicolor/Multijunction Cells

Layering of materials

Multiple bandgaps III-V tandems

http://www.sciencedirect.com/science/article/pii/S136970210770278Xhttp://www.nrel.gov/pv/multijunction.html

Perovskite Solar Cells Perovskite Video

http://cen.acs.org/articles/92/i8/Tapping-Solar-Power-Perovskites.html

“On right, a SEM shows the layered structure of a research type organo lead trihalide perovskite solar cell. On left, a graphic shows how charge moves across these layers.”

Concentrated Photovoltaics (CPV)

Low Concentration PV (LCPV) 2 – 100 suns

Medium Concentration PV 100 – 300 suns

High Concentration PV (HCPV) 300+ suns, 500 to 1000 suns are typical

Multijunction cells have a lower temperature coefficient than silicon

Compensates for increased cost of multijunction cells

Concentrated Photovoltaics (CPV)

Right - http://www.solarfeeds.com/wp-content/uploads/2013/02/cpv-solfocus.jpg

Left - http://www.greenerideal.com/wp-content/uploads/2012/12/amonix-CPV-modules.jpg

Amonix CPV Array

3D Solar Cells

All images from Solar3D, http://www.solar3d.com/technology.php

The 3D structure “traps” and reflects photons, increasing the probability of generating an electron-hole pair.

This allows for a wider angle of incident light.

Produced on silicon, and is therefore cheap and very cost effective.

SEM image of 3Dphotovoltaic structure

3D Solar Cells

Source: http://www.solar3d.com/technology.php

Worldwide Production

Source: EPIA Market Report 2013

Worldwide Energy Usage

Source: http://en.wikipedia.org/wiki/Renewable_energy

Advantages and Disadvantages

Advantages Once manufactured, photovoltaic cells produce pollution-

free energy. Costs of mass production are decreasing as performance

is increasing compared to other energy sources. Efficiencies are quickly increasing; projections indicate

that higher efficiencies will soon be met. Disadvantages

The sun is not always shining; alternative methods are required to store energy.

Can be very expensive to produce advanced photovoltaic cells.

Must be maintained to prevent degradation of performance (dust build up, cell failure, etc.).

Summary and Conclusion

There are many methods of producing photovoltaic cells and the technology, and therefore the efficiency, is rapidly increasing.

Advances in photovoltaics are not solely based on new materials but also new methods of producing photovoltaics.

The biggest issue with solar power generation is the storage of energy when sunlight is not present.

References Jacoby, Mitch. "Tapping Solar Power With Perovskites." CEN RSS.

C&EN, 24 Feb. 2014. Web. 04 May 2014. <http://cen.acs.org/articles/92/i8/Tapping-Solar-Power-Perovskites.html>.

Conibeer, Gavin. "Third-generation Photovoltaics." Third-generation Photovoltaics. MaterialsToday, Nov. 2007. Web. 04 May 2014. <http://www.sciencedirect.com/science/article/pii/S136970210770278X>.

"Technology." Solar3D. Solar3D, 2010. Web. 04 May 2014. <http://www.solar3d.com/technology.php>.

"Market Report 2013." EPIA. European Photovoltaic Industry Association, 2013. Web. 4 May 2014. <http%3A%2F%2Fwww.epia.org%2Findex.php%3FeID%3Dtx_nawsecuredl%26u%3D0%26file%3D%2Fuploads%2Ftx_epiapublications%2FMarket_Report_2013_02.pdf%26t%3D1399341576%26hash%3Dfb2b8b02239998d0c5a33d10000e66f754fc8dc1>.

"NREL: Photovoltaics Research Home Page." NREL: Photovoltaics Research Home Page. N.p., n.d. Web. 04 May 2014. <http://www.nrel.gov/pv/>.

Five Key Concepts

The goal of advanced photovoltaics is to increase the efficiency of converting solar energy into usable electrical energy.

Increasing the number of energy levels by adding more layers of materials will increase the chances of producing electron-hole pairs.

A 3D photovoltaic structure allows for light to generate electricity at wider angles.

By concentrating light onto a small multijunction cell, the solar constant (optical power) is increased.

The greatest issue with photovoltaics is currently with storing the energy that is produced.