Thin film solar cells

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From the course by Technical University of Denmark (DTU)

Introduction to solar cells

375 ratings

Technical University of Denmark (DTU)

Introduction to solar cells

375 ratings

How do solar cells work, why do we need, and how can we measure their efficiency? These are just some of the questions Introduction to solar cells tackles. Whether you are looking for general insight in this green technology or your ambition is to pursue a career in solar, “Introduction to Solar Cells” is an excellent starting point. The course is a tour through the fundamental disciplines including solar cell history, why we need solar energy, how solar cells produce power, and how they work. During the course we cover mono- and multi-crystalline solar cells, thin film solar cells, and new emerging technologies. The course includes hands-on exercises using virtual instruments, interviews with field experts, and a comprehensive collection of material on solar cells. At the end of the course you will have gained a fundamental understanding of the field. This will allow you to identify the most interesting or relevant aspects to be pursued in your future studies or in your professional career.

From the lesson

Thin film solar cells

Moving beyond silicon solar cells, the next important development is thin film solar cells. In thin film solar cells, we see a potential solution to the major problem associated with silicon solar cells: namely energy payback time.

Thin film solar cells3:09

Meet the Instructors

Morten Vesterager Madsen
Researcher
DTU Energy

In this module, we'll talk about thin film solar cells.

Thin film solar cells are, of course, different from silicon solar cells in that

silicon solar cells use indirect band gap materials.

Whereas thin film solar cells use direct band gap materials.

This means we can make much thinner solar cells out of the materials.

Let's have Jørgen Schou from DTU Fotonik introduce the topic.

>> Well, silicon cells typically have an absorber layer about 200 microns.

And in contrast to that, the thin film solar cells, they typically have

solar layer which is typically from 1 to 2 microns, maybe sometimes 4.

So they're much thinner, and it means that they can be used, for example,

sometimes through flexible layers.

You could imagine they could be used for clothes.

>> So as you can see, thin film solar cells use really thin absorber materials,

typically 1 to 2 micrometers thick.

This means we have a much lower material consumption for the solar cell itself.

Furthermore, they can be flexible.

So if they are thin enough and they are made on flexible substrates, well,

they can actually be made flexible and you can install them on rooftops like this.

Thirdly, one of the major benefits of

thin film solar cells is that they require a lot less energy in their production.

We don't need to start out from wafers that we've produced at

very high energy demands.

Instead, we can grow the solar cells themselves on top of the substrate.

And this means we can use a lot less energy to be able to

produce the solar cells.

So let's hear Jørgen explain more about the advantages of thin film solar cells.

>> One thing is that you need much less material.

And this is important because you can use other methods,

for example vacuum-based methods.

And you can also use spray coating methods.

Of course, the typical advantage is that they are more flexible.

But the main point is also that the energy payback

is much smaller because you use less material.

For example, that if you have a silicon cell, then we are talking about

energy payback time, which means the energy to produce a cell and put it up,

which is of the order of years.

But for most of the thin film cells,

it's only an order of some months, maybe 5 to 10 months, no more.

>> So just to reiterate, the main advantage of the thin film solar cells

is really the lower energy payback time.

We use so much less energy because we don't have to fabricate the wafers

first and then do additional steps.

Instead, we just grow the layers, as Jørgen was mentioning here.

So this gives thin film solar cells some unique advantages compared to silicons.

Both the energy payback time, flexibility, and material consumption.

However, as we'll see in this module, there are also some drawbacks.

And that's the main reason we don't see

thin film cells as taking over completely in the market.

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