UNSW researchers set record in solar energy efficiency | Hacker News Reader

UNSW researchers set record in solar energy efficiency

newsroom.unsw.edu.au

104 pointslxm32 comments

Much better source, which means, the journalist who actually checks and provides the sources and doesn't just retype the press release of UNSW is here:

http://www.semiconductor-today.com/news_items/2014/DEC/unsw_...

"This exceeds the record solar photovoltaic module efficiency of 36.7% reported in July by Fraunhofer Institute for Solar Energy Systems ISE of Freiburg, Germany, using four-junction solar cells of concentrated photovoltaic (CPV) solar system maker Soitec of Bernin, France. The 40% efficiency is the latest achievement by UNSW solar researchers spanning four decades, including the first photovoltaic system with over 20% efficiency in 1989."

"The new results are based on the use of focused sunlight, and are particularly relevant to photovoltaic power towers being developed in Australia" (note the comment from adwn here about that!)

The general and technical background of his field was delivered by the UNSW's leading researcher here:

https://www.youtube.com/watch?v=FomSzmIezVQ

Life imitating art. https://www.google.com/search?espv=2&q=helios+one

Actually HELIOS One was based on http://en.wikipedia.org/wiki/The_Solar_Project .

We changed the URL from http://www.sciencedaily.com/releases/2014/12/141207091648.ht..., which pointed to the original UNSW release.

From the original press release (http://newsroom.unsw.edu.au/news/science-technology/unsw-res...):

"The new results are based on the use of focused sunlight [...]"

So it has the usual drawbacks of focused photovoltaics: you need tracking in two dimensions, scaffolding, and active cooling of the PV cells.

Exactly, and what does '40%' conversion mean in this case? Are you collecting twice as much light and focussing it on half the number of cells? Or is there a silicon junction that can convert 40% of the light energy that is incident on it?

> Or is there a silicon junction that can convert 40% of the light energy that is incident on it?

This. The main benefit of concentrated solar power is that the area of the photovoltaic cells can be a lot smaller than the area of the collector (on the order of 100-1000 times). This in turn allows having expensive, but highly efficient PV cells, so you can convert 40% of the insolation on a given area to electricity, instead of only 20%.

A side-benefit is that you can actually use the waste heat from cooling the cells. The ETH Zürich is doing research on this, I think.

We've gotten above 40% before... http://upload.wikimedia.org/wikipedia/commons/a/a5/PVeff%28r...

"We used commercial solar cells, but in a new way, so these efficiency improvements are readily accessible to the solar industry,"

Thank you, I knew I had to have overlooked some aspect.

It's easy to get about 40%, the hard part is doing it cheap enough, and using materials that are not rare.

Slowly but surely we're getting there. I look forward to an inevitable time in the future where the yield will be great and we'll know how to deal with the panels (how to recycle them, etc). It'll be grand.

This is why I've always dismissed and gotten annoyed by comments from fossil or nuclear lovers who were saying for years that "solar is just not there". Of course solar wasn't there where there wasn't even a tiny fraction of investment into it as there is for fossils or nuclear. Put tens of billions of dollars into researching solar, and let's see what we get then.

In recent decades renewable have enjoyed much more investment than nuclear. People love renewables, so governments love renewables, so industry builds renewables.

However, they aren't going to displace coal any time soon, which is what we need to do to avoid the catastrophe we're heading for.

Transmission, storage and integration are all problems that will certainly be solved, with time and many billions spent on research and new infrastructure. Nuclear gives us drop-in zero-carbon replacements for coal plants today, without major changes to existing grids.

If we're going to avoid disaster, 0% fossil fuels must take priority over 100% renewables. I hope and pray that the green movement embraces nuclear as a brother in arms soon.

In 2014, China produced nearly 1/4 of the world's CO2 emissions, with the US coming in second at 15% (however, I believe we're the worst emitters per capita). Within the US, 32% of our emissions come from powering the electrical grid. So globally, that's 32% of 15%, or a little less than 5% of the world's total emissions. If we were to start building nuclear plants and replacing coal plants, the most we could really hope for is a fraction of that 5%, maybe 2 or 3%.

In my mind, the negatives of nuclear outweigh the positives of potentially reducing global emissions by a percentage point or two. Since you agree that nuclear is only a stopgap measure, doesn't it seem like a drastic move?

We're talking about demolishing coal plants to build nuclear reactors within our borders that will produce long-lasting radioactive waste material and pose Chernobyl/Fukushima/Three Mile Island-style threats to public safety, simply so that we can demolish those in a few years when solar/wind/fusion "gets there."

On the other hand, if we used a combination of wind power and home-installed solar panels to simply reduce the energy draw on our coal plants, that would also reduce our home electricity draw. And imagine the economic boost we could see if the government was suddenly offering vouchers for home solar. Not only would that provide a lot of jobs for people to do the installations, but it would boost public interest and investment in solar, strengthening the technology as we spread its adoption.

This isn't to say that I don't think nuclear has its place. I think it belongs on the enormous ships that produce the world's worst pollution. You may have recently heard a report that 16 supertankers produce more (sulphur) emissions than all of the world's automobiles combined. These massive ships aren't held to environmental standards, and they burn some of the filthiest fuels. Yet we've been running nuclear subs without major incident, far away from the general population, for decades.

Why not use nuclear reactors in the worst-polluting vehicles, and encourage the proliferation of safer technologies domestically?

sources: http://www.statista.com/statistics/271748/the-largest-emitte...

http://www.epa.gov/climatechange/ghgemissions/sources.html

http://www.dailymail.co.uk/sciencetech/article-1229857/How-1...

The green movement will not embrace nuclear for two reasons: One is that nuclear produces highly toxic waste with a very long half life. And two, we have already seen that we are not good at making our sites safe and resilient to disaster, nor containing waste post disasters.

It is really to bad because without these facts nuclear would have solved our energy problems long ago.

Instead of electrical or equivalent power efficiency numbers I would like to see benchmarks in terms of $ per KwH after installation. Or in other terms what would be the current sunk cost to get to 40% efficiency.

I mean no disrespect to the scientists and engineers that are working on solar efficiency. They are doing amazing work. I think journalists are seizing headlines for sensational value (i.e. ad revenue) and not doing worthy research.

There is no way to actually calculate that based on lab results. So, it would just end up as a question of who was willing to fudge the numbers more.

Your way makes just as little sense.

If you have a high value space in Tokyo for example, then you want to make the best use of that space. If you have plenty of room, then you care about cost of the install more.

Secondly, this is research technology, not mass production technology. You can't look at the money component of it, because it's not for sale. Not in that manner anyway.

I can't quite grasp this - 40% to what?

Availability of photons?

What is 20% vs 40%? Same size cell putting out twice the power for the same sunlight? Okay, but what makes the 20% ?

40% of the total electromagnetic radiation that reaches the cell is converted to electricity.

What happens with the other 60%? Turns into heat and/or is reflected?

Yup, same as solar energy hitting any surface. It becomes heat.

...or is reflected off...

The photons carry energy. Since energy can't be created, there is a physical maximum amount we can extract from sunlight. These folks are extracting 40% of that maximum.

In Spain or in Australia or in Sahara desert you could get over 1000 Watts per square meter of irradiance in summer.

So with a 40% efficiency you could get 400Watts per square meter if there is no clouds and the panel is perpendicular to the sun.

The good thing is that in Spain, Australia or Sahara desert you have entire months without clouds in some places.

> I can't quite grasp this - 40% to what?

It's power efficiency. Sunlight hits the earth with power density Pi (measured in, say, Watts/m^2) and the solar panel puts out Po for the same area.

They've measured Po/Pi to be 0.4

I don't understand exactly what the purpose of the bandpass filter is. Why does it improve efficiency by only allowing transmission of frequencies that can actually be converted to electricity by the photovoltaics? Wouldn't that light already be falling on the cells? My best guess is that by using the bandpass filter, the temperature of the panels is lower than it would be without them.

There was an interesting discussion about this exact topic on /r/science [1]. Layperson me's (likely mis-)translation of what they were talking about in that thread: the optical bandpass filter might not be a filter in front of all the cells, but the actual cells themselves; or the optical bandpass filter might be on the backs of the cells, reflecting what wavelengths would normally heat up the cells onto a solar thermal collection mechanism.

The concentrated PV+solar thermal designs can get pretty intense: the high concentration designs use liquid metal to carry away a 1600°C heat difference. [2] If the UNSW team has hit upon a way to avoid most of that heat from hitting the cells themselves and redirect it straight into the thermal collection system, instead of trying to absorb the heat away from the cells through thermal conduction, then that is a big win.

[1] http://www.reddit.com/r/science/comments/2okaxt/researchers_...

[2] http://www.greenrhinoenergy.com/solar/technologies/pv_concen...

Solar panels (stock image). Find the rest of our content somewhere after this pointless image. It's not even an ad...

This article is rather lacking in details.

Is this an end of the year cause to show what scientist are doing with grants?

This month we have had so many "Breakthrough" Scientific articles that basically don't match up.

We had super conductor that wasn't 0 Celsius for room temperature. That would be a game changer.

This is focused light requiring active cooling and X and Y axis control.

Graphene article that actually shows that the title wasn't true since we are still at the beginning of the graphene stages without much real world impact.

We also had the carbon filters for use around the world that also is far from being practical or usable yet contrary to its title.

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