No I think that small scale gasification and decentralized MSW sorting and distribution will overtake solar PV in the near future. Key is who will pay for it?. Finally we are questioning why we have to build such large sorting and extinction centers for waste?

We think the price of PV will stabilize because of quality issues in future we recently tested road side installation and 36% were defective after less than 12 months service. We also question the future of the panel why not power textiles the benefit to the user is solar protection this would save far more energy than most panels can make in the near future lab test for textiles is 3%

We like PV panels for example on existing parking lots with 500 parking spaces we can accommodate more than 1MWp of solar panels, we provide shade in the heat and we provide cover when its raining. 1MW car park roof costs around 1.5m Euro in Central Europe we have approximately 2,4 hrs per day usable [its an easy calculation 10%] so 1MW provides us 100kWe

But MSW is a real problem everywhere but to large hospitals, shopping centres and other campus who can satisfy their energy needs [heat and electricity] simply gassification on site. We must look at the needs of a building and then at what the renewable energy solution actually delivers. Emissions are not what the hot plasma engineers will have us believe, the emissions from a Syngas engine has no standard because there are very few ways of detecting the emissions.

A large busy 10,000m2 plus food anchor will produce 4 tons of MSW per day, we can produce 200kWe electricity and 260kWth hot water the CAPEX for such an installation is in the region of 300,000 Euro.

There are pros and cons but consider energy risks not just cost the risk is supply then consider the benefits; you might find this publication interesting http://www.solideagroup.eu/supermarket-hypermarket-zne-with-a-little-help-from-eve-fossil-fuel-free

Yes!

Thanks Susana López Ayala, for your answer. Would you please give us some details?

I definitively agree that better exploitation of solar energy resources must be urgently enhanced. Nevertheless, is worth to pay some attention to Ozzie Zehner's provocative book, entitled "Green Illusions: The Dirty Secrets of Clean Energy and the Future of Environmentalism" (University of Nebraska Press, 2012), and to the discussion it followed. It clearly shows that we need more politically unbiased research considering the possible detrimental effects and the currently largely unrecognized limitations of solar cells, to achieve a better use of this technology.

http://www.nebraskapress.unl.edu/product/Green-Illusions,675003.aspx

http://www.youtube.com/watch?v=v6uVnyjTb58

Thanks a lot Carlos Queiroz, !! but the solution of pollution is very simple. I did not said solid state solar cell only, but we have now Organic Solar Cells

http://cleantechnica.com/2013/01/26/organic-solar-cells-receiving-big-boost-in-efficiency-thanks-to-evolution-inspired-algorithm/

It has already been in my state.."GUJARAT"

How much percent of the available sources of energy?

Gujarat has been a leader in solar power generation and contributes 2/3rd of the 900 MW power generated in the country.

Only if Exxon or BP can patent some part of the technology stream.

Khushbu Chauhan, WAW your city have 600 MW solar power to the nation using solar cells. !! Do you have an idea how much it costs?

http://www.narendramodi.in/cm-to-dedicate-600-mw-solar-power-generation-capacity-to-the-nation/

Hi prof. Walid Tawfik.

Any application of solar energy requires a solar resource assessment.

To take advantage of solar energy is needed to know the timing of lairradiancia surface, that is, as this energy is coming

In Mexico and other countries there are regions of high solar energy available in which you can install solar cells

This makes it a good choice, however you have to reduce constos of materials used as solar cells and continue the investigation of new materials that can reduce costs

addition to assess what the impact of the techniques for obtaining photovoltaic materials in the Environment Management

I think that is obtained after the best method of obtaining materials (which generates less pollution, more efficient and less expensive) solar cells will give us one of the best options

yes we have asia's biggest solar park..214MW already generated..nd will reach upto 1k MW by the end of 2013...oh i dont get into costing..but of course u can look at the gujarat solar policy and tariff plans...

Thanks Susana López Ayala , and Khushbu Chauhan for your valuable discussion and info.!

I do not belive in the next few year the solar energy sources to become as predominant ones. If compare it with wind energy sources, the solar energy is more expensive. So up to use of all wind energy potential, in case of prises of nowadays solar and wind sources, the solar will be not go to predominant position.

Some more important. We come to understanding,that electricity grids used are working good only to penetrating about 20 % distributed renewable energy. So, before practical use of smart grids, that we start to understanding and that are a revolution in the energy transfere and storage, that will become a reality not for few year we will needed by big concentrated energy power generators and solar cells theoreticaly could not become main energy source!

Well, I think there is no comparison of wind and solar power. If we look at the versatile use of renewable energy then the solar energy will lead all of them. The rooftop installed wind stations are not at all cheap or proven technology whereas rooftop and canaltop solar plant does. And as far as price is concerned $0.6/watt is not that much for keeping our climet clean.

Dear Georgi Mladenov, Maybe wind energy sources is good in some North Countries were sun light is not strong enough and depending also on the geographical characteristics. That Solar cells is easy to install in cities where wind stations are not.

In the next few year, absolutely not. The manufacturing capacity that exists today can only supply a few percent of the amount of new electricity generation equipment that's demanded by the global electricity market. Not to mention that even today solar power is still a very expensive way to make electricity, so the demand to grow the sector is not very large. In the longer term, maybe 10-20 years away, I certainly hope so.

Dear Ben Shelef, I expected the prices are related to mass production. That if the mass production increases the prices will goes down. Prices for solar panels began to fall faster than what manufacturers had expected. The prices dropped by about 50 percent last year and have continued to decline this year. At the same time, many manufacturers had built up massive factories and were counting on a huge surge in demand in the global market.

180 Solar Panel Makers Will Disappear By 2015 because the prices goes down.

Please read the forbes report

http://www.forbes.com/sites/uciliawang/2012/10/16/report-180-solar-panel-makers-will-disappear-by-2015/

Hello Walid. Thanks - I'm in the industry, so was trying to help...

Flat panel prices are dropping not because of any breakthroughs in manufacturing (or scaling) but because of over-supply. With subsidies being cut, demand has dropped off, and hence the price decrease. Witness the large amounts of vendors that are going bankrupt.

Even at projected prices of under $1.50 for turn-key non-tracking flat-panel fields, it still remains a very expensive way to make electricity, especially in comparison with natural gas prices which have also dropped recently.

As much as I'd love to see the world move to renewable energy, the numbers right now are regrettably against it.

As far as I know the over supply issue is of some chinese companies only but if we see worldwide production to price graph then of course prices have came down due to huge increse in manufaturing capacity and one of the best examples is FIRST SOLAR which has now beacome a brand for CdTe modules.

The prices of PV modules can not continuously decrease.

More important limit is that in case of zero energy homes have not preferential prize and electricity is expensive.

For big solar farms have limit from electricity grid design. Now the penetration in grids by distributed electrisity generators is up to about 20%. More distributed electricity sources make grid unstable. We must transform electricity grid in smart grid, which take resources , time and will be not ready for next few year.

So solar cells will be not main energy source in the next few years!

One advantage is that wind power is well under way and depends more on the strength of the wind efficiency.

But that does not mean it can not be improved solar cells and with the efforts of researchers.

True, looks away a short-term improvement, but hopefully and of even for an accident or a flash of brilliant researcher.

Both electrification by wind power as solar cells are energies can be used in the right places (and windy areas with high solar radiation) and puden used as alternative sources of electrification

Thanks for all valuable comments, So, I can conclude that, yes there is a hope for both Solar Cells and wind power but we are sure that they will be Main power Sources next years.

As photovoltaic yes and no; yes where applications requiring to connect far generator make this application necessary (i.e on buoys). No if you have other sources more powerful as falling water or gas easily available, in other cases it is a good competitor with other sources

Thanks Luca Patauner for your valuable comment.

I personally think that solar thermal can/may play a vital role in the coming years compared to PV

i do believe in Solar and all type of renewable energy, the only main about solar energy is the optimizing storage devices such as batteries and their cost...

I agree with Adeel Waqas. Ther role of solar thermal is not to be neglected. Do not forget that thermal energy is a large part of the energy demand of buildings. In Italy, after such high incentives on PV plants, the government has recently introduced incentives on solar thermal collectors and plants

Thanks Ehsan Shajiei and Francesco Asdrubali for your valuable comment.

I am really convinced that photovoltaic will be the main energy source in the next future. The problem of stability and safety of grid can be solved by means of a suitable use of storage system. The limit of 20 % of renewable non prommagrable energy source, compared with the traditional thermoelectric power plants, is a limit that holds now with the existent structure of national grid power but in the future the scenario will be completely different.

No I think that small scale gasification and decentralized MSW sorting and distribution will overtake solar PV in the near future. Key is who will pay for it?. Finally we are questioning why we have to build such large sorting and extinction centers for waste?

We think the price of PV will stabilize because of quality issues in future we recently tested road side installation and 36% were defective after less than 12 months service. We also question the future of the panel why not power textiles the benefit to the user is solar protection this would save far more energy than most panels can make in the near future lab test for textiles is 3%

We like PV panels for example on existing parking lots with 500 parking spaces we can accommodate more than 1MWp of solar panels, we provide shade in the heat and we provide cover when its raining. 1MW car park roof costs around 1.5m Euro in Central Europe we have approximately 2,4 hrs per day usable [its an easy calculation 10%] so 1MW provides us 100kWe

But MSW is a real problem everywhere but to large hospitals, shopping centres and other campus who can satisfy their energy needs [heat and electricity] simply gassification on site. We must look at the needs of a building and then at what the renewable energy solution actually delivers. Emissions are not what the hot plasma engineers will have us believe, the emissions from a Syngas engine has no standard because there are very few ways of detecting the emissions.

A large busy 10,000m2 plus food anchor will produce 4 tons of MSW per day, we can produce 200kWe electricity and 260kWth hot water the CAPEX for such an installation is in the region of 300,000 Euro.

There are pros and cons but consider energy risks not just cost the risk is supply then consider the benefits; you might find this publication interesting http://www.solideagroup.eu/supermarket-hypermarket-zne-with-a-little-help-from-eve-fossil-fuel-free

Dear all. Utilization of solar energy will slowly increases, together with wind energy(that is cheeper) and other renevables. Energy storage is a way to extend electricity grid to overlap 20% limit of grid stability, but this is also a kind of grid extencion and need money. Nuclear energy, water generators, gas utilization etc. will continue to be main energy sources in the next future. This is reality, nevertheless that I also like solar and wind energy generation in all kind!!!

I agree with Steve Walker

For an interesting reading: Jaeger-Waldau A., PV Status Report 2011: Research, Solar Cell Production and Market Implementation of Photovoltaics, European Commission DG JRC, Ispra (Italy) . It is available here http://re.jrc.ec.europa.eu/esti/publications/jrc_reports_en.htm

Thanks for your all of and your valuable comments.

The 2012 editionof the PV status report is at:

http://re.jrc.ec.europa.eu/refsys/pdf/PV%20reports/PV%20Status%20Report%202012.pdf

Thanks Roberto Galleano for the PV Status report 2012

According to EPIA, thetre are currently installed in the World 100 GW of PV plants.

http://www.renewableenergyworld.com/rea/news/article/2013/02/100-gw-of-solar-pv-now-installed-in-the-world-today?cmpid=WNL-Wednesday-February13-2013

Dear All, in my opinion, spreading the use of solar cells depends on three major factors two are related to research , which are: cost reduction and efficiency increasing, and the third is related to politics, here the governments should help by sponsoring and encouraging (subsidize) this technology rather than fossil resources which benefit more from this advantage. all these factors related together will without a doubt lead to have the photovoltaic energy as important as one of the main energy resources.

Nassim Mahammedi, thanks for your valuable comment.

You are welcome Professor Walid Tawfik, Good luck

Is this means that only the well developed countries can have the pv soon?

Yes,i am agree.

Solar PV will only be an auxiliary supply. There is really no solution to supply base load other than with traditional power stations e.g: Coal, Gas, Nuclear, Hydro etc..

Solar PV only supplies power while the sun shines. One can store the energy in large UPS', but it's too expensive an energy to put through another step, decreasing the already bad efficiency.

In an industrialized country such as Germany, the peak production from solar PV coincides with their demand peak, but the base load still has to come from other sources.

I agree with you Dr. David Johnson, I am still have hope about mass production lowing the cost. For example, In India they have used it especially at Gujarat has been a leader in solar power generation and contributes 2/3rd of the 900 MW power generated in the country as mentioned above. So I hope that the cost problem will be solve soon.

http://www.narendramodi.in/cm-to-dedicate-600-mw-solar-power-generation-capacity-to-the-nation/

I fully agree with Me David Johnson,as long as ,there is not a break through in the manufacturing technologies of solar cells that leads to lowering its costs and increasing its effeciency

Dear prof. Walid Tawfik,

I do think that PV is and specially will be a trascendental source of enery for the near future. "solar cells will be one of the main energy sources in the next few years" thats for sure. However, I disagree with the technological view that compare only energy efficiency. Plants-vegetables should not be replace by PV panels, as all the ecological services would be lost. PV should be used in unused surfaces (as roofs, chanels, etc.) or in desertic zones.

We need to remember from where we come and where we go with renewables: Climate change is not only CO2. Water, polution, biodiversity, soil protection, etc., are as important as green house gases. Ecosytems should not be treat by renewables.

To place PV instead of human food crops or forests seems to me unsensible.

Cheers

Probably now you are right but I am really convinced that the situation will change very soon (increasing of price of oil, increasing of the number of earth inhabitants, increase of pro-capite yearly demand in the most populated nation). On the other hand the dynamic of the displacement of one source with another is very low (e.g. Oil Vs Coal took 80 years). So despite of the relative ( in some place the grid parity has been already reached) high price of photovoltaic kwh, now the transmission and distribution, as well as control sytems, have to reviewed especially to collect high quantity of non-programmable sources

I agree with Giuseppe Tina, that by time the cost will decrease and efficiency will increase for PV.

Just some elements for the discussion:

i) At this website http://sunbird.jrc.it/pvgis/ you can simulate how much energy a PV system can generate in Europe and in some other parts of the world.

ii) According to my knowledge, quite conservative, 1 kw peak PV system costs around 3000 euro for a turn-key domestic installation and it produces around 1100 kwh/year energy in northern-central Italy locations (southern Italy, Spain, Greece, etc can easily reach the 1400+ kwh/year energy production). A system can lasts for more than 25 years, so the total cost (3000 euro) divided by the life time energy production ( +/- 27500 kwh) gives a figure of 0.11 Euro/Kwh: very close to, or even less, what the end consumers pay for a kwh electricity. The so called 'grid parity' is already here.

Dear Giuseppe, in term of cost now PV silicon is selling at 60c/Wp with prediction to go to 42cents/Wp in 2015. Thin film techology is now at 1.7% for CdTe and 20.4% for CdTe with price at lower than 50 cents/Wp.I am pretty sure that the pV market will continue is steady grow. We will need all the renewable source (biomass, wind, tidal) perhaps even nucleat ( altought I will prefer not). The problem is also on how to store the energy (thermal, hydrogen, chemical). There is a lot fo interest in this sense in UK at the moment.

Yes, Roberto Galleano, on the long run the cost is close to conventional ones and the link you sent to me shows that the PV mostly in the southern European which is more sunny !!

Thanks:)

The efficiciency for CdTe is 18.7% wrong number added :) from First Solar

I think in our rush to jump onto the PV bandwagon, we forget about the costs dealing with the toxicity of solar cells. What happens to the CdTe at end of life? If we just throw it into the landfill, it contaminates our groundwater sources. We are treating PV as an panacea and ignoring the toxic effects during both production and end of life stages. We can't trade air pollution for water pollution and call it a success. I call it a punt. Much like our grandparents left us to clean up the messes they left behind, we're just leaving the this mess for our grandkids. Unless we have a full cradle to grave solution that looks not only at emissions, but toxicity, I think we need to tread more carefully.

The theoretical limit for silicon is 33%. Altought the highest efficiency is the 25.0% obtained by UNSW more than 15 years ago.

Dear Terri, the recycling is another point that needto be adressed. I am sure you use everday NiCd battery which contains 100 times the amount of Cd modules. There are several paper I can post on this argument. We need to start to think and fast on how to find alternative form of energy the climate change is one of the most important consequences.

This is the standard graph shown in many presentations but I think it is a litle old and the multi junction efficiency has already been beatenhttp://www.google.co.uk/imgres?imgurl=http://www.observatorynano.eu/project/filesystem/images/2en.p04.jpg&imgrefurl=http://www.observatorynano.eu/project/document/2016/&h=851&w=1372&sz=201&tbnid=wGarXn3Iz_zYDM:&tbnh=76&tbnw=123&zoom=1&usg=__aqoka5dWLgwSG4QtAxojn9QYE_8=&docid=HIQ6RR4GuAOBxM&sa=X&ei=LbVUUZi-Lqiw0AXN1YFo&ved=0CFQQ9QEwAw&dur=598. However, these efficiencies are under ideal test conditions and for 40% you also need significant concentration of the sun. This couldn't be installed anywhere but only in the sunniest areas. As O&M goes this isnt cheap either as the best environments for these are usually in the desert and require significant cleaning to keep their high performance.

PV is getting cheaper and closer to grid parity for some technologies in given regions but subsidies would significantly improve the situation which is freely handed to other (oil, gas , nuclear) technologies.

Dear Terri Chu, I think oil , nuclear are more danger to environment than PV. I agree with Sean Macdougall 100% . For Sanaa Hayel , I think we can reach 40% in best conditions of sun light concentrations.

Dear Walid you are absolutely right. There are III-V cells that can reach 44% at 947 suns. You can find more info at http://phys.org/news/2013-01-award-winning-pv-cell-efficiency-higher.html

Thanks Gianfranco Claudio, for your valuable comment.

Yes, I read about these NREL's gays that their new designfor application under sunlight concentrated to 1,000 times its normal intensity by low-cost lenses .

I think the problem of the cost can be solved in future by mass production and government support. Maybe also, new materials could be discovered with higher efficiency in future :).

As someone who works in this field, I have to say that the answer for this specific question is: "absolutely no", unless your definition of "few years" is +20 years.

This question has been answered with wrong promises and statements that fool the public for more than 30 years already. Read this statement made by the environmentalist and erstwhile presidential candidate Barry Commoner (in 1976):

"Mixed solar/conventional installations could become the most economical alternative in most parts of the United States within the next few years."

I am afraid that many of the comments in this topic here are falling under such a category.

Thanks Ahmed Abdelrahman , for your valuable comment.

I'd like to share this link with everybody working with solar cells:

"Progress in Photovoltaics" publishes every six months updated tables with best efficiencies for materials and modules - the last version comes from this january

http://onlinelibrary.wiley.com/doi/10.1002/pip.2352/full

Thanks Luca for your comment and information about the link. I am just wandering if the given data are results of laboratory measurements or of commercially available solar cells in the market

I believe they are mostly research results, but "they must have been independently measured by a recognised test centre listed elsewhere". However, many results are from private enterprises, so I think they will strive to make their modules available to the market, once they communicate their record efficiencies.

Prof.Walid, who knows at what time new technology pops up and take over conventional generation, but the Solar PV technology is proving potential source where insolation is sufficently available. solar PV being clean, non rotaing/heating/smoking technology that can be installed in nearest place to the consumer....best place is roof top of the shed, can prove best technology for the distributed generation and to make the consumer self sufficient and make them capable to play in the energy market.

Photovoltaics have a role to play in the big picture, especially if used correctly. In UK the PV installation was driven by Feed-in-Tariff, encouraging householders to install PV arrays and paying them for electricity generation. Many poor installations were carried out, some to the extent of costing more in replacement of connections, mountings, inverters, maintenance and repairs that promised income. Eventually the UK government reduced the FITs resulting in glut of PV in UK, prices of PV plummeted from about £3/W (at peak) to somewhere like £0.78/W over a matter of about 18 months.

In my opinion and experience PV electricity generation for Grid is a fallacy, by the time the electricity is generated, inverted and put through the grid and does a circuit and is transformed several times, each time with losses, 1kWhr generated may end-up being only about 0.25kWhr. Therefore it is best used at point of generation or within short distance of generation and not even inverted, but used as DC within the Smart-Hub. Also cooling the PV panels helps and especially in very sunny countries, hybrid panels would do better and extend the life of panels by cooling the back of the panel extending its useful life, as well as generating hot water for residential use.

Two of the main energy sources for the next few years remains the coal and the nuclear. The PV should wait another one or two decades to challenge those two...

PV is already a reality with over 65GW installed and with cost below $.60 For silicon and thin film. In a TeraWatt society we will probably need all the renewable resources (tidal, wind, biomass) and nuclear (the last oneed to adress lots of issues such as the wast).

Unfortunately, no matter of cost, PV energy conversion is discontinuous and related to weather conditions, thus needs backup.

Sure that is why energy storage will play a fundamental role in the coming years. I guess nuclear will be something we have to deal with.

The question was; PV being safe, clean, durable and almost free after installation. Not as the primary energy source like oil, coal, gas or isotopes. PV should be seen as a reducer of fossil fuel dependance.

Bravo Gianfranco, totaly agree with you. Battery technology (possibly lead crystal) to permit complete discharge or hydrogen generation and coupling with fuel cells is the answer , to store the excess through the day and subsequently use at night.

Dear Roland I suggest you to do a proper literature review before make some silly comments. PV is the highest growing market in the world and there are already 65 GW power plant in the world. You probably do not know the difference between thin film amorphous used in calculator and c-Si, CdTe, CIGS typically used for PV production.

Dear Mr.Ronald,

you should remember that strength of renewable sources including solar depends upon its geographic condition, hence can not be compared on bases of countries with less radiation vs countries with higher radiation, and its increasing installation worldwide proves the significance although lots of research going on in the technology, energy engg. has lots of hopes from solar PV.

I partly agree with this. Reliability is one of the important factor to look after

There are a lot of false story going around solar PV and sunny countries. Germany which has the largest PV module installed in Europe has the same quantity of solar irradiation than UK. The major point is the grid parity and soon northern country with the increasing cost in electricity and gas bills will be forced to go on solar. It si just question of time. The reduction in prise of $/W is also helping the process.

Hi Roland & Hemang (talking of strength, perhaps meaning efficiency), as far as efficiency of PV. On a retrofit project in UK that I was involved in (sponsored by Technology Strategy Board), the PV is the only element that has performed better than expected. The ASHP, MVHR, Grey Water Recovery, solar panels and external insulation system have all performed below the manufacturer’s promises (perhaps the PV manufacturer was pessimistic?). From the point of view of Germany not being suited to PV (FITs for PVs 15 years now?), UK is some 3 degrees further north and yet PVs here perform adequately. Prices are also dropping with £0.60/W as the lowest I have seen. Problems encountered were few, poor installation anything from shading from trees to poor inverters, cleaning off the algae, some black-wire corrosion on poorly connected arrays. Otherwise they (PV) are a fix and leave it alone system. From the point of view of unsightliness, all due consideration has to be given to the historic locations. Yet again Gianfranco is absolutely correct, scientific understanding is often a barrier which can be easily negotiated by research.

Yes , I think so, PV can take a huge share of load by putting financial policies encourage end users to install it easily and build a flexible systems (Microgrids) able to sell the surplus energy to the main grid

Thanks to all contributors. It is a very rich debate.I just want to add that the IEEE Power and Energy Journal ,Vol 11 No 2 March/April 2013 is dedicated to PV and their future in the Power scene. Who is interested to read more about this issue can have a look in that Journal. Thanks to all again

yes.......... definitely helpful in development of Microgrid as one of the micro source......

People don't really know that the era of PV grid parity is coming. PV energy is cheaper than grid. In Taiwan, 1/3 families (about 3.8 millions) and 2/3 commercial sector's (about 700,000 shops) are qualified for grid parity. PV is able to replace nuclear energy. The big challange is that, distributed power tech is not ready. FIT (feed-in-tariff) policy mislead the direction of PV system tech development. PV+battery+smart grid is the answer.

I agree with Bin-Juine Huang

this article about the detials

PV with battery in smart grid paradigm: Price-based energy management system

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6317679&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6317679

thanks for your comment Driss Soubane

PV are suitable for domestic ,comercial as well as industrial requirement of power and are feasible with small payback.

I hope so in near future Lallan Verma.

Malaysia has just announced a new solar farm project near the KL Int Airport, guess solar energy has a future, at least in Malaysia. Prof Walid, is it true solar cell efficiencies have reached 40%?

I think it's at 24% still.

Wan Ahmad Najmi Wan Mohamed , yes , using focusing technique.

I suppose you mean solar thermal concentrators using mirrors. I was actually thinking about a PV cell efficiency

The next stage of solar cell efficiency improvement, from 40% to 50%-efficient production cells, is perhaps the most important yet, since it is in this range that concentrator photovoltaic (CPV) systems can become the lowest cost option for solar electricity, competing with conventional power generation without government subsidies.

http://www.spectrolab.com/pv/support/Solar_Cell_Generations_over_40_Efficiency.pdf

The greatest benefits come to countries at the equator where the sun exposure is the greatest. Sahara desert, in my opinion, is a potential power generator for the future. The real estate is just wide open for development. Note that PV orientation is important. I know that PV don't like heat therefore direct exposure to scorching sun does not take a full benefit of sun light. Therefore solar panel will have to do both, sunlight collection (and heat shielding of PV) and heat collection.

Adam Szewczyk thanks for your comment, and also the problem of dusty weather that the PV panel cover by dust daily which reduces that efficiency so much and need special mechanical cleaning.

Thanks Srikanth Chakravarthy for your comment. As I mentioned before PV could reach now 40% efficiency. The problem is to Convince governments to support it since it expensive.