Photovoltaic cells are undergoing rapid development and are dropping dramatically in price. They are  a greater threat to coal fired power than the carbon tax.

There are many types that have been developed or are being developed.  For example:

Crystalline Silicon, Amorphous silicon, , Dye-sensitized solar cell, CdTe,  Copper indium gallium selenide, etc.

On this chart you can see the development of the different cells and who has been holding the record for efficiency on each.

Prof Green of UNSW has been specializing in the silicon crystal and has held the record for many years. He is now onto second and third generation silicon cells.

Tindo

Tindo produce a panel with a 240 V AC output. So they are not in series and are not affected by one of the panels being in shade. 

Made in Adelaide, Aust.

Output of PV cells worldwide

http://pvoutput.org

Solar cell windows

US researchers have developed a transparent solar cell that could allow windows in homes to generate electricity while still being able to see outside.

The team from UCLA made new polymer solar cells that produce electricity by absorbing infa-red light and it is nearly 70 per cent transparent to humans.

"These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications...more importantly, they can be produced in high volume at low cost," said study leader Yang Yang, a UCLA professor of materials science and engineering.

Hydrogen improves Silicon cells.

The team from the University of New South Wales has discovered a mechanism to control hydrogen atoms so they can better correct deficiencies in silicon – by far the most expensive component used in the making of solar cells.

“This process will allow lower-quality silicon to outperform solar cells made from better-quality materials,” Scientia Professor Stuart Wenham, from the School of Photovoltaics and Renewable Energy Engineering at UNSW, said.

Standard commercial silicon cells currently have a maximum efficiency of around 19 per cent. The new technique is expected to produce efficiencies between 21 and 23 per cent.

Source

Raygen

A field of mirrors concentrates sunlight 750 X onto PV cells.

The cells are 40.4% efficient and developed at UNSW. They are water cooled to prevent overheating with loss of efficiency and shortened lifespan.

As only a small amount of PV cell needed, the more expensive high efficiency cell can be used.

Silex was following the same path but has now closed down.

Raygen first installation at Newbridge outside Melbourne Source - Raygen

Hybrid​ PV and hot water claims 60% efficiency

By generating hot water from a PV array the total heat collection from sunlight is boosted to 60%. If the hot water is used to run air conditioning then it can run after the sun goes down.

A Technique Solar Module for a nominated solar collection area of 3.5 square metres produces a total of some 2.1 kW of power.

 

A standard PV cell panel of some 2.1 kW requires 21 square metres of area.

http://www.techniquesolar.com.au/technology

Concentrated solar on water cooled PV cells

IBM is researching and publicising the project to concentrate sunlight 2,000 times onto 3 junction PV cells. Normally the heat would destroy them, or render them inefficient.

They have developed a series of micro branched channels in side the chip, similar to the blood flow in human cells. The wall thickness between the PV surface and the water, is only a few tens of micrometers. The water absorbs the heat and takes it away.

The PV cells are claimed to convert 30% of the solar photons to electricity, and collect another 50% as heat. If this heat is used for heating, then is is  100% efficient, but if the water is say 100^oC, then the maximum heat that can be used for say, electricity generation, is only about 10%. (20% theoretical).

The cost is low because the PV cell is only 1 x 1 cm, and produces 250 watts. And the dish is made of concrete with simple mirror design.

They claim they will be able to produce electricity for 10 c/kWh. Normally PV costs 25 c/kWh, and coal is 5-10 c/kWh. They do not mention whether the waste heat is counted in this cost. Presumably not.

They plan to use the waste heat for heating or cooling buildings, or desalinating water. Presumably this is with multiple effect evaporators.

Source 

CSPV - Concentrating S​olar PV

750 sq M orf mirrors concentrate sunlight onto 1 sq m of PV collector. It is 40% efficient and produces 200kW of electricity.

The cells are tripple junction GainP/GaAs/Ge cells.mThey are twice as efficient as normal cells, but more expensive. With such large area of mirror, the cost of the cell is not important.

For greatest efficiency the cells ae cooled. If a use is found for this heat then the whole system become more efficinet.

Click on image to enlarge

If the heat collected is used to heat compressed air used in compressed air energy storage, then this process has an increase to 100% or more round trip efficiency.

www.raygen.com/

Holographic foil claim 28% efficient

A holographic process filters out the wavelengths that would heat the silicon, then concentrates the rest onto small segments of silicon. Only 3%  of the area is needed greatly reducing the costs. The backers clamiman efficiency of 28%.  The hologram foil can be printed cheaply. 

Solar bankers

Spin Cell

V3Solar has developed a new PV cell to produce electricity at only 8c /kwh. If this is true it will be a revolution.

The most expensive part of PV is the silicon cell.

Their process uses lenses to concentrate sunlight 20X or 30X onto a small silicon cell.

Normally this is a problem because the cell heats up and become less efficient. By spinning the cell, it moves away before it can heat up. The website is very vague on the technical details.

They also claim to have improved the efficiency of the PV cell from 20% to 24%.

The main features of the cell are: 

Captures light from the full hemisphere of the sky to maximize the use of available insolation
Motion of the cell assembly provides cooling solving a fundamental problem of systems using concentration
The moving cell assembly can be used to produce an alternating current (ac) output directly without a traditional inverter
The cooling effect is sufficient to allow for the use of mass produced one sun cells available from hundreds of manufacturers globally
Enhanced efficiency is hypothesized via a “cascade effect” whereby cells retain and build some energy as they pass by the sequence of lenses
The system is self-contained and doesn’t require additional racking and mounting – it can be mounted directly to earth screws, poles or other low cost foundations.

Source

At this stage (Jan 2013) the process is still in the development stage.

Other systems under development use water to cool the cell and provide hot water.

First true “all-carb​on” solar cell developed

Researchers at Stanford University have developed an experimental solar cell made entirely of carbon. In addition to providing a promising alternative to the increasingly expensive materials used in traditional solar cells, the thin film prototype is made of carbon materials that can be coated onto surfaces from a solution, cutting manufacturing costs and offering the potential for coating flexible solar cells onto buildings and car windows.
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Nano particles in thin films - ANU

PV installation. X axis is GW.

Small-Molecule Organic Photovoltaics (SM-OPV™)

Global Photonic is developing organic cells based on Gallium and Arsenic and organics. They predict these will be built and sold for 45c/watt. Source

GPEC’s OPV™ technologies are based on “small molecules” each acting as an individual PV cell at the nanometer scale.

PV cells made from small-organic molecules have several advantages:

Maximum possible efficiency

Single p-n junction crystalline silicon cells have a theoretical efficiency ceiling of 33.7 percent (the Shockley–Queisser limit). The best commercial c-Si cells from SunPower (Nasdaq: SPWR) clock in at 24 percent efficiency. Alta Devices has set gallium arsenide (GaAs) solar cell efficiency records at 27.6 percent.

An infinite-junction solar cell under concentrated sunlight has a theoretical limit of 86 percent. The real-world record is held by Solar Junction at 44 percent in a triple-junction cell at 947 suns. More

Proposed increase in efficincy of PV cells.

Conventional architecture of triple-junction solar cell

Biohybrid solar cell

More than 40 years ago, scientists discovered that one of the proteins involved in photosynthesis, called Photosystem 1 (PS1), continued to function when it was extracted from plants like spinach. Then they determined PS1 converts sunlight into electrical energy with nearly 100 percent efficiency, compared to conversion efficiencies of less than 40 percent achieved by human-made devices. This prompted various research groups around the world to begin trying to use PS1 to create more efficient solar cells.

Progress to date has been slow

Ref

Colloidal quantum dots

RESEARCH TRIANGLE PARK, N.C. – Researchers at RTI International have developed a new solar technology that could make solar energy more affordable, and thus speed-up its market adoption.
The RTI solar cells are formed from solutions of semiconductor particles, known as colloidal quantum dots, and can have a power conversion efficiency that is competitive to traditional cells at a fraction of the cost.
Solar energy has the potential to be a renewable, carbon-neutral source of electricity but the high cost of photovoltaics – the devices that convert sunlight into electricity – has slowed widespread adoption of this resource.
The RTI-developed solar cells were created using low-cost materials and processing techniques that reduce the primary costs of photovoltaic production, including materials, capital infrastructure and energy associated with manufacturing.
Preliminary analysis of the material costs of the technology show that it can be produced for less than $20 per square meter—as much as 75 percent less than traditional solar cells.

Source

Super-Efficient Solar Cells Possible Through Use Of Exotic Form Of Silicon, Generating More Than One Electron-Hole Pair Per Photon

By utilizing an exotic form of silicon, silicon BC8, it is very likely possible to significantly raise the efficiency of solar cells, according to new research headed by the University of California, Davis.

Solar cells currently in use generate one electron-hole pair for every photon that hits them, and are capable of a theoretical maximum efficiency of ‘only’ 33%. But by utilizing nano-particles of an exotic form of silicon known as silicon BC8, it is possible for each photon to generate multiple electron-hole pairs.

“This approach is capable of increasing the maximum efficiency to 42%, beyond any solar cell available today, which would be a pretty big deal,” said lead author Stefan Wippermann, a postdoctoral researcher at UC Davis. “In fact, there is reason to believe that if parabolic mirrors are used to focus the sunlight on such a new-paradigm solar cell, its efficiency could reach as high as 70 percent.”

Clean technica

Next-Generation Of Solar Cells, Capturing More Sunlight With Microbeads

“Micro beads” may be the key to extremely thin (and much cheaper) next generation solar cells. Solar cells 20 times thinner than the solar cells of today are only 5-7 years off, according to the nano-scientists that are currently developing them.

The estimate, as of right now, is that the super-thin solar cells will be on the market by 2020, which should help to greatly cut down on manufacturing and production costs.