Solar cell efficiency

"Solar cell efficiency" was the topic of investigation for Sunny (Grade 5 boy). His topic was initially "Solar panels" until session 15).

Student reflection and PowerPoint files
Transcript of student reflection
Voice-over script
Researcher reflection
Conceptual consolidation rubric

 

 

Session 1

Solar panels 210711.ppt

 

 

 

I'm thinking that I need to find out how it changes from one type of energy, heat energy, into electricity that powers things.

I know that solar panels are pretty expensive, but they are good to save money on electricity. I know that they take something from the sun and do something with it to make it power stuff.

Sunny is very descriptive with both his reflection and his voice-over script.

It allows me as a researcher to focus on where he's going rather than trying to interpret what he's saying.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 2

(Did not record reflection)

Solar panels 280711.ppt

Sunny spent most of the session animating auto shapes as he is keen to get going. Unfortunately, his voice-over text hasn't changed and he didn't record a reflectiony so his understanding of the concept probably hasn't evolved much since the previous session.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 3

Solar panels 110811.ppt

Today I wondered if, that a solar panel takes heat or light from the Sun?

Solar panels are pretty expensive, but they are good to save money on electricity.

They take something from the sun and do something with it to make it power stuff.

 

 

The voice-over script is the same other than changing the 1st person tense.

Sunny is now asking more relevant questions so I have moved him up in the conceptual consolidation rubric under identification of relevant variables.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 4

(Did not record reflection)

Solar panels 180811.ppt

This week Sunny focused on the novelty of animation. I have found this to be a common distraction for some students (usually boys) where they just want to create movement.

Sunny is very capable so I'm not too concerned about his tangent into animation techniques.  The voice-over script didn't change this week so I've included the preliminary animation which he was working on.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 5

Solar panels 250811.ppt

Today I learnt that solar panels take light and not heat from the Sun, and, I learnt something about a photovoltaic cell.

It was convenient for me in my discussion with Sunny to be able to literally drop a term like "Photovoltaic cell" into his concept map without having to offer or expect a full explanation.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 6

Solar panels 010911.ppt

Today I was out for most of session but when I came back I brought a new computer so now I have my software with Internet.

Sunny was only able to attend the last 10 minutes of this session.

It was beneficial for him to change computers from now on to ensure that he has Internet access.

There are a variety of animations on solar power online which will be helpful for Sunny to determine a suitable way to represent this topic.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 7

Solar panels 080911.ppt

New solar panels 080911.ppt

Today I researched about photovoltaic cells. And I think the abbreviation for it is PV. And that's what solar panels are pretty much made up from.

I think they take photons from the Sun's light and covert them to energy.

Blank (i.e., deleted)

Sunny had deleted his voice-over script (which I only noticed after the session). He also deleted his concept map slide so I will ensure that he re-instates these during the next session.

I have, however, moved his "Self-assessment" along the conceptual consolidation rubric as he is increasingly confident about what constitutes a solar panel.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes
Absent session 8 (Grade 5 camp)

Session 9

(No PowerPoint file)

Today I learnt that there’s more than one layer in a solar panel.  And I don’t quite know what they are yet but that’s something I’m going to be looking at next time.

Blank (i.e., not saved)

I'll try to spend a larger percentage of the next session with Sunny as he has had some technical issues lately.

Sometimes the setbacks from losing work can be minimised when the basic framework is restated with increased clarity.

I will suggest that the handful of layers which belong in a solar panel are not merely shown and explained but, rather, explained as they are successively added. In this manner the animation will literally build a solar panel.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 10

Solar panels 201011.ppt

For my animation I’ve decided to make it so that I’m going to build the solar panel as I go through.  So I’m going to start with one layer and then do the next one and so on.

Solar panels are pretty expensive, but they are good to save money on electricity. They take something from the sun and do something with it to make it power stuff.

Solar panels are big square disks that take light energy from the sun and  convert it to a different type of energy called electricity. A solar cell (also called photovoltaic cell or photoelectric cell) is made of monocrystalline silicon wafers

 

Sunny decided to implement my suggestion to build the imagery from scratch rather than present it and then explain it.

Sunny's voice-over script has been expanded with a new section covering photovoltaic cells whilst still retaining his introductory remarks about the cost and benefits of this technology.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 11

Solar panels 271011.ppt

I found out that there are three layers in a solar panel and there are N type and P type semiconductors.  And some of, only some things in them, most things are the same, but, two things can be switched around to make an N type into a P type…I think.

Sunny's voice-over script hasn't changed this week nor has the imagery. This is because he has realised the importance of finding out the essential structure of a solar panel so he can generate his imagery.

The definitions that he encountered for "N type" and "P type" semiconductors were identical except for certain variables which were switched around. Interestingly, Sunny concluded that each type of panel was interchangeable when, in fact, they are complete opposites. This should be resolved soon when he looks into the structure and composition of the semiconductors.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 12

Solar panels 031111.ppt

Today I, my computer shut down randomly so I didn’t get much done but I did decide that I might need to see a semiconductor, actually how it works and then I might be able to understand how a solar panel works.  And I need to know the difference between an N and a P type semiconductor.

This topic has proved difficult for me in terms of assistance as it is one where I really need to expand my own knowledge.

Sunny's voice-over script hasn't changed this week but I'm now more aware of the reference to the solar panel doing something to the light rather than the light doing something to the solar cells.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 13

Solar panels 161111.ppt

I spent most of the session working on the voice-over script so, what I’m going to say when the animation’s playing.  And I’m probably going to finish it next time I work on it.  All I need to…well, what I need to find out now is what…which semiconductor is which…if it’s P to N or N to P.

A solar panel is made up of photovoltaic cells.

A photovoltaic cell converts light energy into electricity.

A conductor is something that electricity can travel through.  Conductors vary in their ability to allow electricity to flow.

Semiconductors are made from materials such as silicon. Other chemicals are then added to change the behaviour of the electricity.

P type Boron

N type Phosphorus

The silicon is treated with an antireflective coating to absorb more energy.

Solar cells are usually quite small so many cells are combined to make a solar panel.

This voice-over script is a complete revision. I acted as both scribe and mentor whilst we discussed the final animation in term of an unfolding explanation.

We are both unclear on whether the current flows from P (positive) to N (negative) or vice-versa. Sunny speaks for us both when concluding his reflection with the research goal of determining "which semiconductor is which".

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes
Absent session 14
Absent session 14

Session 15

Solar panels 011211.ppt

Solar panels 011211b.ppt

I’m considering changing my topic to "Solar cell efficiency".  I’m going to cover the same thing I was going to cover in my old animation but just briefly at the start.  And, then I’ll focus on how to make a panel, or cell, more efficient.

Sunny changed his topic to "Solar cell efficiency" today in response to my suggestion that we narrow the scope to efficiency issues. This allows us to cover important and interesting issues around solar cells without getting stuck at the atomic level.

His voice-over script hasn't changed this week so I have drafted a new script for him to review during our next session.

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes

Session 16

Solar panels 061211.ppt

Solar panels 081211.ppt

Solar panels 081211b.ppt

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2.ppt

2 fix.ppt

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3 fix.ppt

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Today I recorded my voice-over script and finished it off.  And I started animating my animation.  And I decided not to do a 3D solar panel because it’s too tricky to make.

Solar panels are made up of photovoltaic cells.

A photovoltaic cell converts light energy into electricity.

At the heart of a photovoltaic cell is an NP junction where negative and positive plates made of silicon and other materials are placed close together.  Electrons want to jump across from the Negative to the Positive side.  This force is known as voltage but energy is still needed to make electrons jump across.

Energy in the form of photons from sunlight enables electrons to jump across which creates the flow of electricity which is known as current.

Even the best solar cells only achieve around 40% efficiency.

There are several things that can improve the efficiency of solar cells:

Silicon is very shiny so most of the sunlight is reflected which is a waste of energy.  This is why solar panels have a dark non-reflective coating so that more light flows into the cell.

Light can have different amounts of energy just like it can have different colours.

Most solar cells are designed to create electricity with only a small amount of light but this means that only a low voltage is produced.

The strength of the voltage known as Band gap energy depends on how much energy is required for electrons to jump across the NP junction.

In strong sunlight you get extra current but the voltage doesn’t really increase. New research involves multi-junction cells which have more than one electric field.  This allows the panel to operate in low light and also take advantage of stronger light with increased current and voltage.

I have moved Sunny along on the conceptual consolidation rubric for both "Identifies relevant variables" and for "Self-assessment".

During this final session, I asked Sunny to complete the newly devised "Voice-over script / imagery table" so I would have clear instructions on how to complete the animation to his satisfaction. The only scene which he didn't know how to represent was the multi-junction cell. The following imagery ended up being used after trialling other ideas like diagonal plates showing varying band gap energy:

Multi-junction cell

 

 

Uses correct terminology With assistance Simplified terminology Some correct terminology Actual terminology

Identifies relevant variables

Not apparent With assistance Basic understanding

Deep understanding

Identifies relationships between variables Not apparent With assistance Basic understanding Deep understanding
Self-assessment. Does the student think that they understand their topic? No Not really Basic understanding Yes
Session 17 was the debriefing session.

 

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