Process of increasing solar cell efficiency?

[Fizicks]

Hello all.

I've recently gained an interest in solar cells and it's development. I know the basic working principle of solar cells, but other than that I'm quite clueless about the field.

I was wondering, what is the process of increasing solar cell efficiency like? Are there analytical ways of improving solar cell efficiencies? Or do researchers experiment with different material, structures, and designs through trial and error?

Any input is greatly appreciated!

Thanks.

[PNjunction]

I found this video quite informative as it wasn't tied to a manufacturer, but had some great details I wasn't aware of - and how much of it can actually go wrong or out of tolerance quickly.

Youtube "Solar Cell Manufacturing Process" by Irtria

Heh, now I KNOW why ebay cells aren't A-grade!

For the first couple of seconds I thought it was going to be totally cheesy, but then turned out ok.

[revolvesolar]

Always used latest material related to solar energy products!
Never Use Outdated material and products

Hope it Helps!....

Mod note - That is not a very bright statement - especially when you are using it to drop a link. Next time you are gone.

[EugeneZ]

Hello all.

I've recently gained an interest in solar cells and it's development. I know the basic working principle of solar cells, but other than that I'm quite clueless about the field.

I was wondering, what is the process of increasing solar cell efficiency like? Are there analytical ways of improving solar cell efficiencies? Or do researchers experiment with different material, structures, and designs through trial and error?

Any input is greatly appreciated!

Thanks.

Not sure if this topic is still actual, but anyway, I'll give my input as was required

Well, the process of increasing solar cells performance combines both mentioned ways: analytical and experimental You have to think before you make a trial with different conditions and materials, then analyze it an so on...

Generally speaking, each step of solar cells producing process could be improved (both materials and process tolerances) and in the end resulted in some Eff. gain. However, different steps provide with different cell performance boost. In other words there are some key factors which influence on cell power is huge: initial silicon quality and it's properties repeatability from batch to batch, diffusion quality and stability, ARC (anti reflection coating, the blue stuff on the front of the cell) quality and finally metalization step (area of my job).

All of the steps are very complicated in their way. For example, metalization means three steps of applying screen printable metal pastes on to the cell and final co-firing in a belt firing furnace. The most important are the front silver paste and back Aluminum. The front paste is in charge for Isc (short current), while the back Al is for the voltage. The third back silver paste has a function of a connection pad (busbars), and it's "efficiency" is in consumption and price.

So here are the possibilities for cell Eff. improvements. One of the challenges for the front metalization is to reduce shadowing provided by front grid pattern and reduce contact resistance as much as possible (for better conductivity), while for the back Al is to increase voltage.

Interesting thing is that pastes manufacturers and solar cells producers are different companies, as you can understand. And the R&D process for a new generation solar cells normally is a result of collaboration of both parts. The problem is all know-hows are kept secretive. For example, I have a paste which to my experience ensures cell power gain. I go to my customer - cell producer, he makes a trial and it fails due to the difference in conditions, silicon, other materials and so on... However, step by step we get closer to the success by optimizing materials and conditions.

It's just a short example .

maybe it would be interesting for you: When I've started 4 years ago, the conventional mono silicon cell Eff was about 17-17.5%, while for multi-silicon around 15.5-16.00%. Today these values are much higher: for mono it's 18.0 - 18.7 (some companies say 19%), while for multi 16.5 -17.0%. And during these 4 years no new mass and cheap technologies were invented (I'm not talking about SunPower or Sunyo HIT, their share is not so big and products are very expensive). That was just a result of collaboration of different materials suppliers, cells producers and institutes.

I hope the story is not very confusing

[PNjunction]

Funny you should mention the anti-reflective coating - I was thinking the other day about custom panels where the ARC might be directional for special purposes:

Let's say a special application was that the panels could only be mounted vertically, not at an angle. I was wondering if an ARC could be developed that did the heavy-lifting of refracting between angles of say 30-70 degrees or so so that angled light from above would refract once and hit the cells straight on. Instead of angling the panel, use a directional ARC if need be. Might even be useful for horizontal panels where the sun is low on the horizon most of the time etc - although again this is a very special case that doesn't allow for panel tilt.

This arc would be a permanent custom replacement / order as it would replace the conventional ARC, and would have to be manufactured that way.

That Youtube video was fascinating as I had never thought about reducing leakage-current in the cells during the process, and/or not going too deep with the plasma.

Hmm.. off the top of my head to reduce shadowing: how about making the grid pattern itself photovoltaic serving as both a conductor for the larger cell mass, and then contributing a very wee part back into the system as a whole? heh, probably not economically viable... You got me thinking now...

[inetdog]

Funny you should mention the anti-reflective coating - I was thinking the other day about custom panels where the ARC might be directional for special purposes:

Let's say a special application was that the panels could only be mounted vertically, not at an angle. I was wondering if an ARC could be developed that did the heavy-lifting of refracting between angles of say 30-70 degrees or so so that angled light from above would refract once and hit the cells straight on. Instead of angling the panel, use a directional ARC if need be. Might even be useful for horizontal panels where the sun is low on the horizon most of the time etc - although again this is a very special case that doesn't allow for panel tilt.

This arc would be a permanent custom replacement / order as it would replace the conventional ARC, and would have to be manufactured that way.

Even with complete elimination of the reflection at near parallel angles of incidence, you cannot avoid the other factor that the area of the panel will intercept a smaller cross section of available sunlight. That cos(theta) factor will still remain and will limit the range of off-axis angles that are practical. Given the added expense of ARC and customization of the ARC for a particular angle, I doubt that any benefit gained there would be economical.

[russ]

Must have been from a universities web site such as MIT. Generally spreading BS while trying to impress the peasants.

[green]

You're right Russ but... no matter the form or where or from who innovation comes from it is very important. I do understand what you're saying though.

Green

[russ]

When bloggers troll the research university web sites and blog about it they rarely have any concept of how difficult it is to get from the basic research stage to selling a product - both from a technical aspect as well as engineering.

The universities are 100% correct to study and research some of the wild ideas - that is one of the reasons they are there.

Unfortunately the internet has lowered the quality of reporting so far that most is more or less gossip today.

[PNjunction]

The "nano" buzzword is the dead giveaway.

[solarlady]

Hi All,

There is a lot of confusion about solar cells efficiency. The big question is which technology results in how much efficiency and the difference between solar cells and the solar panels efficiency. Here I got a comprehensive write-up on this subject and found it very helpful. hope it can be of some use to u too:

[

[russ]

According to MIT Technology,

Increasing the amount of electricity a solar panel produces is one of the most effective ways to reduce the cost of solar power.
Most solar panels convert less than 20 percent of the energy in the sunlight that falls on them into electricity. A new $2.4 million project funded by the U.S. Advanced Research Projects Agency for Energy aims to greatly increase the amount of sunlight that becomes electricity. Its goal is a conversion efficiency of more than 50 percent, which would more than double the amount of power generated by a solar panel of a given size. This would cut the number of solar panels needed in half and potentially make solar power more competitive with fossil fuels.

Re-posting crap from MIT and dream land is meaningless. You are not spreading information but spreading BS.

This bit is pablum for the greens out there and nothing more. There are cells reaching into the 40% efficiency now - horribly costly though. http://www.worldwatch.org/node/4803

[bonaire]

These studies imply that the new high efficiency panels will be cost comparable to existing mainstream panels. Even 10% better efficiency now has a steep price increase per panel. When anything produces more, it costs more. Be it people to engines to crops.

I will say that today's mainstream modules are indeed cheaper than two years ago and each module is more efficient. But not at the scale the study implies it will do.

The biggest lame study going now is the five times cheaper and five times more capacity battery research funding the DoE has started to push.

[russ]

MIT has a boatload of experts - experts at milking funding. They do have results as well - too bad the results can't keep up with the blather.

[Sunking]

According to MIT Technology,

This would cut the number of solar panels needed in half and potentially make solar power more competitive with fossil fuels.

Nice PR but completely false. There are 41% efficient solar panels on the market you can buy right now made by Spectrolab a division of Boeing Aircraft. They only have a few customers mainly Defense Contractors that make satellites. They cost up around $100/watt