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Speaker 1: Brought to you by the reinvented two thousand twelve camera.

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Speaker 1: It's ready. Are you hey there, Text Stuff listeners, This

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Speaker 1: is Jonathan Strickland and I have got a request for

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Speaker 1: all of you. Now, Chris and I have decided that

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Speaker 1: we're going to try and experiment. We're doing our first

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Speaker 1: crowd sourced episode of tech Stuff and we want to

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Speaker 1: know what your pick is for the worst video game

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Speaker 1: of all time. Now, nominations you can. You can make

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Speaker 1: one nomination. You nominate one game, and you need to

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Speaker 1: tell us the name of the game and the platform

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Speaker 1: it was on. And it could be any platform. It

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Speaker 1: could be an arcade game, it could be a PC, Mac, Xbox,

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Speaker 1: PS three, Nintendo handheld console. It can be web based

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Speaker 1: if you like. But just you let us know what

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Speaker 1: the platform is so we can make sure we count

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Speaker 1: that as the votes. So you can nominate your game

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Speaker 1: either through email, which is tech Stuff at how stuff

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Speaker 1: works dot com, or you can nominate through Twitter or Facebook.

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Speaker 1: And we're gonna put a cut off date on this.

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Speaker 1: I want to have the episode go up by the

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Speaker 1: end of September of eleven. So let's say you need

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Speaker 1: to get your nominations in by September eleven, So if

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Speaker 1: you get those nominations into us, we will make sure

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Speaker 1: we include those in the process and we will have

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Speaker 1: an episode where we give you the worst video games

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Speaker 1: of all time based upon the votes of our listeners.

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Speaker 1: Thanks a lot. Can't wait to hear from you. Get

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Speaker 1: in touch with technology with tech Stuff from how stuff

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Speaker 1: works dot com. Hello, everyone, Welcome to tech Stuff. My

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Speaker 1: name is Chris Poet and I am an editor at

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Speaker 1: how stuff works dot com. Sitting across from me as

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Speaker 1: always and for some reason twisting up a rubber dinosaur

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Speaker 1: is senior writer Jonathan Strickland, Little Darlin, the smiles returning

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Speaker 1: to the faces, Little Darling, it seems like years since

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Speaker 1: it's been here. H. That was a nice choice for

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Speaker 1: today's topic, which is I think something that everyone will

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Speaker 1: find electrifying. Yeah, and in fact, this comes to us

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Speaker 1: courtesy of a Google Plus suggestion. This comes from Adam,

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Speaker 1: who says this may be a bit simple, but have

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Speaker 1: you guys ever done an overview of solar technology and

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Speaker 1: solar tech history? Just re listened to your battery podcast

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Speaker 1: and it made me wonder more about alternative energy sources. Adam, um,

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Speaker 1: your definition of simple and my definition of simple are

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Speaker 1: too very different things. But but yeah, we're gonna talk

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Speaker 1: about solar power, solar cells also known as photo voltaic cells,

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Speaker 1: and uh kind of where it came from. M Yeah,

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Speaker 1: they're not they're certainly not new. UM. We have an

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Speaker 1: article about how solar cells work on the website UM

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Speaker 1: which discusses how they were used in the nineteen fifties

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Speaker 1: in space uh space technology. Yeah. In fact, the well,

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Speaker 1: to go back even further, the photoelectric effect, which of

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Speaker 1: course is the basis of photovoltaic fells, that was first

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Speaker 1: discovered by a or at least first observed by a

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Speaker 1: French physicist named Edmund Beckerel. It's an eighteen thirty nine. Wow,

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Speaker 1: that was some time ago. Yeah. Now, granted he observed

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Speaker 1: that certain materials, if if exposed to sunlight, would produce

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Speaker 1: a certain amount of electric current, but there wasn't really

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Speaker 1: any way of putting that to any use at the time.

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Speaker 1: It was just it was an interesting scientific observation and

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Speaker 1: that was the the limit of it. Einstein himself began

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Speaker 1: to ruminate on this, decided about, you know, to kind

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Speaker 1: of think about what is the nature of light, how

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Speaker 1: does it interact with the nature of electricity, what's the

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Speaker 1: relationship there? Um? And then he actually won a Nobel

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Speaker 1: Prize based on his observations. Now, the first module photo

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Speaker 1: vote vol take module, because a module is a collection

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Speaker 1: of photo voltaic cells. In fact, we can get this

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Speaker 1: out of the way and really early on, if you

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Speaker 1: want to talk about like the a sense of scale,

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Speaker 1: an individual photo voltaic cell, when grouped together with other

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Speaker 1: photo voltaic cells, makes a module, and groups of modules

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Speaker 1: together make an array. So it's just it's just as

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Speaker 1: a question of scale. So array isn't a group of

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Speaker 1: modules and modules a group of photo photo voltaic cells.

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Speaker 1: I'm gonna stumble over that over and over in this episode,

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Speaker 1: so I hope you guys are listening at twice speed

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Speaker 1: so that the chipmunk is messing up over and over

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Speaker 1: and not me. Anyway. The first module was built by

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Speaker 1: Bell Laboratories, and that was in nineteen fifty four. And uh,

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Speaker 1: at that point they were thinking of it kind of

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Speaker 1: they think they called it a solar battery. They didn't

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Speaker 1: even call it a solar cell at that point, and

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Speaker 1: it was kind of considered to be an interesting idea

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Speaker 1: but not at all practical. I think they determined that

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Speaker 1: based upon the amount of work and uh it took

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Speaker 1: to develop and manufacture that first module. They were getting

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Speaker 1: about a watt for every I think it's two fifty

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Speaker 1: bucks per what, which is not efficient doesn't even compare

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Speaker 1: to other materials at all. Right, So not something that

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Speaker 1: they could implement immediately in order to to try and

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Speaker 1: generate electricity. And and then later on the fifties and

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Speaker 1: then into the sixties, really primarily in the sixties, that's

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Speaker 1: when the space industry began to use these solar cells

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Speaker 1: in order to get power for vehicles that be traveling

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Speaker 1: through space and also satellites that would be placed in

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Speaker 1: orbit around the Earth. You know, you have to have

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Speaker 1: power going to these satellites somehow, and you know, batteries

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Speaker 1: can provide power, but power batteries will die out and

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Speaker 1: there's no way of recharging easily when you can't tether

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Speaker 1: the device to the Earth. Okay, spot Nick, enough of that. Um. So,

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Speaker 1: solar cells were a way to be first for satellites

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Speaker 1: to gather power and remain in orbit functioning properly for longer.

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Speaker 1: Um Now, why are we even talking about solar power

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Speaker 1: in the first place. Well, mainly because it's abundant, and

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Speaker 1: one would imagine inexpensive. I mean, you've got about a

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Speaker 1: thousand watts of energy per square meter of the planet's surface. Yeah,

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Speaker 1: that's a lot of energy. Uh. You know, the Sun

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Speaker 1: shoots out lots of lots of energy towards the Earth.

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Speaker 1: I mean, really, the Sun shoots out lots of energy everywhere,

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Speaker 1: but we on Earth are happy to receive quite a

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Speaker 1: bit of it. Uh and we some of it gets

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Speaker 1: absorbed in the atmosphere, some of it gets absorbed by

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Speaker 1: the surface of the Earth, some of it is converted

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Speaker 1: into energy via photosynthesis by the agitation, and then the

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Speaker 1: rest of it just kind of gets reflected back off

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Speaker 1: into space. So there's all this energy that is not

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Speaker 1: being used in any meaningful way at all, and it's

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Speaker 1: just it's going away. And uh So the thought is

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Speaker 1: using solar cell technology, we could perhaps harness some of

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Speaker 1: this energy that otherwise we would just lose um. And

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Speaker 1: that's the basis behind the the push for solar energy. Now,

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Speaker 1: the engineering challenges that face us as we try to

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Speaker 1: actually harness that power are what kind of keep us

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Speaker 1: from just adopting it wholesale. That and also, I mean

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Speaker 1: there's some practical problems besides the engineering issues. Right, Like,

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Speaker 1: if you live in a place where there's not a

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Speaker 1: lot of you don't get a lot of sun, then

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Speaker 1: solar energy doesn't make a whole lot of sense. It

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Speaker 1: would be a lot it would be a heavy investment

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Speaker 1: for very little payoff. Um. Now, if you live in

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Speaker 1: a place that tends to get sun most of the error,

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Speaker 1: than solar cells make a lot more sense. Yeah. The

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Speaker 1: basics involve something that we've talked about many times in

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Speaker 1: the show. Semiconductors, which is a material that allows some

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Speaker 1: electrons to flow, but not all the available electrons to flow,

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Speaker 1: permits some flow of electricity, but not there's some control, right.

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Speaker 1: It acts somewhat like a conductor and somewhat like an insulator.

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Speaker 1: And uh and and it's the relationship between the semiconductor

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Speaker 1: and photons, which are the particles that we can you know,

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Speaker 1: units of light energy really because you talk about how

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Speaker 1: light can be both a wave and a particle, but

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Speaker 1: really talk about a photon having a certain amount of

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Speaker 1: energy um. And the energy has to be enough to

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Speaker 1: cause the semiconductor to conduct electricity. And I guess we

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Speaker 1: can get into how that works and the basis behind that,

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Speaker 1: and uh really comes down to things like a selah

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Speaker 1: common crystals. Yeah, yeah, well it's possible. I should say

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Speaker 1: upfront that it's not always silicon. That's true, silicon being

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Speaker 1: the predominant material it's used. I think for the purposes

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Speaker 1: of of this early part of the discussion, I think

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Speaker 1: we should think of the solar cells that you see

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Speaker 1: mounted on roofs and different places, because those are the

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Speaker 1: ones with which most of us are familiar. So, yeah,

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Speaker 1: the dominant semiconductor used in that as silicon. Right, So

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Speaker 1: in order to understand how the solar cells work, we're

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Speaker 1: gon we're gonna have to take a little a little

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Speaker 1: chemistry lesson here and learn more about silicon itself. So,

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Speaker 1: silicon is an atom that has fourteen electrons. Yea. There

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Speaker 1: are three different shells um and the first two are

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Speaker 1: are full. There are two and eight electrons, but uh

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Speaker 1: the outer shell has room for eight, but generally only

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Speaker 1: has four. So, uh, you know the shells case you

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Speaker 1: don't remember, the shells are essentially they represent a general

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Speaker 1: space around the nucleus of the atom where electrons are

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Speaker 1: capable of existing. And because electrons are negatively charged and

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Speaker 1: and like charge, Uh, what's the word thank you? It

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Speaker 1: just escaped repulse to repelled? Yes, that those those sometimes

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Speaker 1: they away from thank you. Yeah. I was like, I

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Speaker 1: think they don't like each other. And I was like,

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Speaker 1: that's probably not quite as sophisticated as our listeners expect,

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Speaker 1: well they expected from me. You're so so like like

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Speaker 1: charges repel one another, Thank you, Mr Palette. Without you,

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Speaker 1: I would have just been sitting here quiet and Matt

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Speaker 1: would have been snickering in the other room. Space is

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Speaker 1: getting really read. It was really entertining, you know, it

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Speaker 1: happens sometimes my brain just gives out on me. So, yes,

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Speaker 1: light getting back to it like charge repels like so, so,

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Speaker 1: these electron shells represent a space where electrons are capable

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Speaker 1: of existing, and you can't have more electrons in that

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Speaker 1: space because the negative charges would push push the electrons out.

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Speaker 1: So then the second shell, that's the one where you

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Speaker 1: can have up to eight electrons there, and then the

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Speaker 1: third shell, up to eight can exist there, but only

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Speaker 1: four are there in a in a silicon atom, So

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Speaker 1: if you you know, there's room for more electrons there.

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Speaker 1: In a way, I hesitate to use the word want

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Speaker 1: because it's just sentience. But it's it's these atoms are not,

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Speaker 1: as far as we know, sentient in any way, tend

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Speaker 1: to Yeah, they there is a a there's a tendency

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Speaker 1: for these atoms to require more electrons in that final

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Speaker 1: shell to have a full outer shell. Right, that's that's

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Speaker 1: the goal of these atoms, as if there were like

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Speaker 1: some sort of conscious goal. So, so when you get

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Speaker 1: a whole lot of silicon atoms together, they tend to

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Speaker 1: bond together, um because they begin to share electrons in

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Speaker 1: their outer shells, and so they get really really tight.

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Speaker 1: So a silicon atom will bond with four other silicon

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Speaker 1: atoms to fill up that outer shell. And each of

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Speaker 1: those silicon atoms are bonding to up with up to

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Speaker 1: four other silicon itoms to fill up their outer shell,

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Speaker 1: and this creates a crystalline structure, and they bond with

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Speaker 1: four friends and so on and so on. So, yeah,

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Speaker 1: you get this crystalline structure. Now, once you have this,

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Speaker 1: we're talking right now about a pure silicon crystalline structure, right,

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Speaker 1: So when you get all these these outer shells full

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Speaker 1: of electrons, there's a problem and that it doesn't really

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Speaker 1: conduct electricity at that point because you don't have any

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Speaker 1: free electrons, free raining electrons to uh to move through

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Speaker 1: that material. So if you introduce electricity, it's hard. It

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Speaker 1: takes a lot more energy to break the electrons out

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Speaker 1: of those bonds so that they will flow through. If

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Speaker 1: you you can do it, but you have to put

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Speaker 1: a lot of energy into the system. Yeah. What you're

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Speaker 1: looking for here is free carriers, the electrons that are

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Speaker 1: wandering around. Um. That will allow you to conduct electricity.

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Speaker 1: You know, if there are a lot of them. Um.

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Speaker 1: So what you have to do next is really dope. Yeah, yeah,

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Speaker 1: you have to dope the silicon. Now that means that

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Speaker 1: you are introducing impurities or other elder ingredients if you will,

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Speaker 1: into the silicon crystal. So you know when you think

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Speaker 1: about impurities and usually that has a negative connotation to it,

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Speaker 1: but in this case, it's something that's really necessary you

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Speaker 1: can put there. Now, there are two different routes to go, right.

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Speaker 1: You can put in atoms into You can introduce atoms

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Speaker 1: into this mixture that have more electrons in their elder

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Speaker 1: shell than silicon does. Now, that's going to introduce extra

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Speaker 1: electrons into this crystall instructures. Some electrons that are not

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Speaker 1: bonded with other atoms. So that's where you've got these

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Speaker 1: free carriers, and then it doesn't take as much energy

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Speaker 1: when you introduce energy into the system to break those

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Speaker 1: electrons free from the structure. UM, it's still requires energy

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Speaker 1: because they're the those electrons are still attracted to the um,

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Speaker 1: the positively charged nucleus, but it doesn't take as much

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Speaker 1: as if all the atoms were bonded to one another

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Speaker 1: with no free electrons. Yeah, if you used, for example,

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Speaker 1: phosphorus and uh introduced that to pure silicon, first of all,

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Speaker 1: they would really hit it off at the party. Yes.

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Speaker 1: Oh wait, I'm thinking of introducing in a totally different

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Speaker 1: way anyway. So if you dope some pure silicon with

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Speaker 1: with phosphorus um, you would add you would essentially be

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Speaker 1: adding free electrons or source of free electrons, let's say that,

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Speaker 1: and that would create an end type uh semiconductor and

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Speaker 1: meaning negative because again, electrons have a negative charge, so

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Speaker 1: you've actually got more of a negative charge than a

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Speaker 1: positive charge because you have these extra electrons. Uh. Now, now,

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Speaker 1: if you were to introduce a material that had fewer

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Speaker 1: electrons in its outer shell than silicon, you would end

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Speaker 1: up with spaces for electrons where no electrons exist. That

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Speaker 1: would be a P type of silicon, yes, because you

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Speaker 1: would have a space for electrons, but there would be

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Speaker 1: no electron to fill that space. Now, if you were

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Speaker 1: to take these two types of silicon, the N type

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Speaker 1: and the P type and put them together, then the

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Speaker 1: like the extra electrons from the N type want to

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Speaker 1: go and again want being just they tend to go

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Speaker 1: to the P type because there's a positive hole there

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Speaker 1: and you have the negative charged electrons in the N type.

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Speaker 1: So there's this immedia desire to transfer or tendency to transfer.

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Speaker 1: Chris is just laughing because I'm adding anthropomorphiz sizing electrons. Look,

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Speaker 1: some of my best friends are free carriers. Okay, hey,

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Speaker 1: let's go to the P type. Oh, man, is too early.

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Speaker 1: I didn't want to see the animated version of this.

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Speaker 1: Little know, the electrons with little faces drawn on a

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Speaker 1: big smile. Hey, so you got a hole there? I

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Speaker 1: can feel that. So the uh yeah, there's this tendency

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Speaker 1: for the electrons to move across. Well, this creates this

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Speaker 1: actually can create a barrier that acts like a diode.

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Speaker 1: And if you've listened to our Basic Electronics podcast, you

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Speaker 1: know that a diode is this channel that allows electricity

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Speaker 1: to flow one way but not back in the other

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Speaker 1: directions one way street exactly. And in this case, interestingly enough,

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Speaker 1: it will allow electrons to transfer from the PA side

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Speaker 1: to the inside, but not the other way around. Oh yeah,

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Speaker 1: so because that's not what they normally want to do, right.

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Speaker 1: So now this is where we finally get into introducing

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Speaker 1: photons into this system. All right, So you've got this,

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Speaker 1: You've got the system here where you've got this barrier

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Speaker 1: between the N type selicon and the B type cell

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Speaker 1: con and you've got the potential for electrons to move

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Speaker 1: across this barrier if you introduce energy into the system,

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Speaker 1: and the photons are that energy. So when a photon

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Speaker 1: of a proper amount of energy strikes the silicon, UH,

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Speaker 1: it can create enough energy for the electrons to transfer

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Speaker 1: across this barrier. Now, once the electrons cross cross that

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Speaker 1: barrier from the P type to the ND type UH,

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Speaker 1: they are now in a negatively charged environment, so that

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Speaker 1: the tendency is for these electrons to try and get

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Speaker 1: back to the positively charged environment, but they can't pass

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Speaker 1: that barrier. So if you were to create a pathway

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Speaker 1: from the negative side to the positive side. The electrons

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Speaker 1: would follow that pathway and do whatever it was you

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Speaker 1: wanted them to do if it meant they could get

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Speaker 1: to the positive side on the other end. So it's other.

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Speaker 1: In other words, it's like a really exclusive party and

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Speaker 1: you're like, Okay, you can come into the party, but

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Speaker 1: you gotta carry my stuff into the room with you.

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Speaker 1: And people want to get the party, You're like that totally.

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Speaker 1: The party is worth it. I will carry your stuff.

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Speaker 1: That's kind of the the analogy I'm going with here.

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Speaker 1: There's a party I want to go to tonight. Did

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Speaker 1: I mention that anyway? So, so do you do you

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Speaker 1: have to power somebody's computer to do it? No? Fortunately not.

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Speaker 1: So the electrons will do work along this pathway. And

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Speaker 1: that's just a basic circuit, right, it's a and it's

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Speaker 1: it allows current to flow. So photon hits the silicon

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Speaker 1: uh and as long as the photon has enough energy

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Speaker 1: to break that bond, the electron goes across the barrier,

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Speaker 1: wants to get back to the pea side, will go

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Speaker 1: through this pathway to get back to the peace side,

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Speaker 1: and along the way will do work. So that work

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Speaker 1: might be lighting a light bulb. That's the basic example

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Speaker 1: that you see in most uh sure drawings. So that's

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Speaker 1: that's the basic principle. Now we gotta address a couple

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Speaker 1: of other minor points to actually play a big role

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Speaker 1: in in y solar cells work and why they aren't

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Speaker 1: as um why we don't see them everywhere right now, Yeah,

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Speaker 1: you mean, like, um, the fact that, well there are

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Speaker 1: other components to the solar cells to sure how light

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Speaker 1: bounces off stuff like silicon. Right, Silicon tends to be

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Speaker 1: very shiny, which means that some photons when they strike

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Speaker 1: the surface are just going to reflect off and not

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Speaker 1: get absorbed at all, which is a problem. If you're

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Speaker 1: not absorbing the energy, then you cannot, um, you don't

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Speaker 1: have enough energy for the electrons to break free by

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Speaker 1: the way, that that we call that the band gap energy,

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Speaker 1: to to break free of that that final electron shell.

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Speaker 1: So one problem is that not all photons have the

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Speaker 1: same amount of energy because light comes in a variety

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Speaker 1: of forms. You know, we talked about the spectrum of light.

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Speaker 1: So you know, you can see light like visible light

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Speaker 1: and has a pretty wide spectrum, but even beyond that

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Speaker 1: is an even wider spectrum infrared light, ultraviolet light, and

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Speaker 1: then you know of course all the different colors. Well,

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Speaker 1: each of those types of of light have a different

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Speaker 1: amount of energy, and if the energy is not sufficient

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Speaker 1: to UH to overcome the band gap energy, the electron

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Speaker 1: is not going anywhere. So if the energy is more

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Speaker 1: than what the band gap needs, that electron will move,

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Speaker 1: but some of that energy is wasted. Like for example,

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Speaker 1: if I need if I can lift a hundred and

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Speaker 1: ten pounds and there's a weight in front of me

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Speaker 1: that's a hundred pounds, I can lift that up. But

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Speaker 1: if there are two weights that are a hundred pounds,

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Speaker 1: I'm still only gonna be able to lift one up.

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Speaker 1: Even though I'm capable of lifting over a hundred pounds,

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Speaker 1: I'm not capable of lifting two hundred pounds. So if

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Speaker 1: you get a photon that actually has say twice as

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Speaker 1: much energy as the band gap energy, then you could

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Speaker 1: actually move to electrons per photon UM. So that's another problem.

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Speaker 1: So how do we get past the reflective problem? Well,

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Speaker 1: usually they get around it by putting on some kind

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Speaker 1: of material that is an anti reflective property, um, just

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Speaker 1: to keep the photons from bouncing away UM. And that

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Speaker 1: that's one thing they have to do. They also have

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Speaker 1: to put a cover plate on it, you know, glass,

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Speaker 1: essentially to keep the solar cell from being damaged. Because

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Speaker 1: again we were talking about the solar cells that you

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Speaker 1: see the arrays that you see in on rooftops and

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Speaker 1: um and for in some instances on the side of

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Speaker 1: the I see a lot of them on the side

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Speaker 1: of the road where they have some kind of equipment there, um,

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Speaker 1: you know, a sign or something that they want to

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Speaker 1: use to uh, you know, to provide messages to people

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Speaker 1: who are traveling on the roadway. They'll have a giant

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Speaker 1: or not a giant, but a large solar panel out

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Speaker 1: there to help power the sign. Um. You know, that's

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Speaker 1: sitting out there all the time, so you know, you

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Speaker 1: don't want it to be damaged by the rain or

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Speaker 1: or anything. Um, So you know, you have to have

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Speaker 1: these other things that are they're going on. But unfortunately,

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Speaker 1: these uh, these solar cells are not particularly efficient. Yeah,

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Speaker 1: there's actually there's several reasons why efficiency is a problem.

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Speaker 1: One of those is, you know, I mentioned the whole

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Speaker 1: band gap energy problem. Whereas one temptation would be to

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Speaker 1: build a solar cell that be able to gather as

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Speaker 1: many photons as possible. In other words, aim for the

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Speaker 1: lowest common denominator, like create material that's going to have

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Speaker 1: the lowest band gap energy, so that even weak photons

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Speaker 1: would be able to make electrons flow. Well, here's the

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Speaker 1: problem with that. Current is that would be the number

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Speaker 1: of electrons that move through a system. Right, But there's

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Speaker 1: another element called voltage, and and voltage is more like

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Speaker 1: if you want to think of it in terms of plumbing,

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Speaker 1: voltage would be the pressure and current would be the

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Speaker 1: amount of water um. So voltage and current together, When

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Speaker 1: you combine the two together, you get power. That's the

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Speaker 1: product of current and voltage. So you mustapply the two

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Speaker 1: and you get power. So the power from any system

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Speaker 1: is going to be dependent upon the current and the voltage.

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Speaker 1: If you use material that has a low band gap energy,

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Speaker 1: you get a lower voltage in that system, so you've

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Speaker 1: actually decreased the voltage. So the current increases, but the

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Speaker 1: voltage decreases, so the product does not necessarily become enough

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Speaker 1: for it to be a good return on investment. So,

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Speaker 1: in other words, you could create something that creates has

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Speaker 1: more current but a lower voltage, the power is less.

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Speaker 1: It does it doesn't do as much work as say,

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Speaker 1: materials that have a higher band gap energy, even though

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Speaker 1: you've even though you are discounting more photons in that

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Speaker 1: in that other system, the photons that are hitting are

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Speaker 1: producing more energy. UM. So that's one issue. Although you

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Speaker 1: can kind of work around that in a way. You

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Speaker 1: can create a multi junction cell. And a multijunction cell

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Speaker 1: is uh. You can think of that as layers of

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Speaker 1: cells on top of one another, and one layer has

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Speaker 1: a certain band gap energy, and then the next one

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Speaker 1: has a different band gap energy, and the next one

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Speaker 1: has yet another band gap energy. In order to capture

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Speaker 1: as many of these photons as possible, and that will

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Speaker 1: help a little bit. So that's one way you can

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Speaker 1: do it. It's a very expensive thing to do, but

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Speaker 1: NASA has been doing it for years. That's that's what

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Speaker 1: NASA solar cells tend to be, our multi junction cells

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Speaker 1: because you know, you want to you want the satellites

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Speaker 1: to last a really long time so um, and you

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Speaker 1: want them to be very efficient. But that's one problem

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Speaker 1: with efficiency. Another is just the design of the solar

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Speaker 1: cells themselves. In order for these electrons to hit a

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Speaker 1: pathway a circuit, you know, they have to they have,

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Speaker 1: you have to create that pathway for them, and that

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Speaker 1: raises some challenges. Where do you put how do you

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Speaker 1: create this pathway the top of the solar cell. It's

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Speaker 1: hard to make a conductive layer, right, because I mean

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Speaker 1: usually we tend to use metal. Metal is a good conductor.

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Speaker 1: Most metals are good conductors. Yeah, and the series resistance

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Speaker 1: of silicon is so high that it causes a lot

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Speaker 1: of loss. Mean, if you're using something like copper, right,

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Speaker 1: it would do great. Yeah, but copper doesn't have that

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Speaker 1: photovoltaic quality. There's the problem. So if you're using metal

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Speaker 1: to conduct the electricity, to act as the circuit, to

431
00:25:12,760 --> 00:25:18,280
Speaker 1: act as the pathway for these electrons, um, the question is, well,

432
00:25:18,520 --> 00:25:20,880
Speaker 1: you can't really, you can't encase it in metal because

433
00:25:20,880 --> 00:25:23,120
Speaker 1: if you did, then no photons would get through. There

434
00:25:23,119 --> 00:25:25,439
Speaker 1: has to be at least one side open. You know,

435
00:25:25,520 --> 00:25:29,320
Speaker 1: you can create some conductive material that is, uh, you can,

436
00:25:29,400 --> 00:25:32,560
Speaker 1: you can weave through the glass. But there's also a

437
00:25:32,600 --> 00:25:36,640
Speaker 1: concern that you know, photons are these tiny, tiny, tiny particles,

438
00:25:37,200 --> 00:25:41,040
Speaker 1: and even the thinnest metal material that might make up

439
00:25:41,080 --> 00:25:45,040
Speaker 1: a grid in a solar module, for example, will block

440
00:25:45,240 --> 00:25:50,240
Speaker 1: some electron photons. Rather which means that you're losing efficiency

441
00:25:50,320 --> 00:25:53,800
Speaker 1: that way. So that's that's one of the reasons why

442
00:25:53,840 --> 00:25:57,000
Speaker 1: solar panels can have problems with efficiency is that just

443
00:25:57,160 --> 00:26:00,960
Speaker 1: based on the design itself, in order to conduct those

444
00:26:00,960 --> 00:26:07,080
Speaker 1: electrons and provide electricity, you're blocking off some of the photons.

445
00:26:07,280 --> 00:26:09,560
Speaker 1: So you're never going to get a hundred percent efficiency

446
00:26:09,600 --> 00:26:13,160
Speaker 1: because just based on the technology itself, it's blocking its

447
00:26:13,200 --> 00:26:21,720
Speaker 1: own source of power. That's frustrating. Photons just shake. Yeah,

448
00:26:22,240 --> 00:26:26,480
Speaker 1: So they've been working on trying other types of materials, uh,

449
00:26:26,640 --> 00:26:30,000
Speaker 1: stuff like a morphous silicon, cadmium tell your ide and

450
00:26:30,119 --> 00:26:34,920
Speaker 1: copper iridium, gallium decelenide. Had some of that the other day.

451
00:26:34,960 --> 00:26:39,400
Speaker 1: It was delish, But yeah, I mean these are using

452
00:26:39,440 --> 00:26:42,680
Speaker 1: these materials, uh, you know, they've they've been trying to

453
00:26:42,760 --> 00:26:46,760
Speaker 1: find some advantages. One of those is that with some

454
00:26:46,800 --> 00:26:50,040
Speaker 1: of those materials you can create a thinner material, a

455
00:26:50,040 --> 00:26:53,240
Speaker 1: thinner panel or thinnel thinner cell, and they call them

456
00:26:53,240 --> 00:26:57,560
Speaker 1: thin film solar cells. And basically, yeah, these are very

457
00:26:57,600 --> 00:27:00,800
Speaker 1: neat because, um, a lot of the again the arrays

458
00:27:00,800 --> 00:27:05,040
Speaker 1: that we had in our initial example are pretty solid.

459
00:27:05,520 --> 00:27:09,080
Speaker 1: They don't they don't bend, and the thin film solar cells. Yes,

460
00:27:09,080 --> 00:27:12,919
Speaker 1: they do break, but um. Actually a couple of companies

461
00:27:12,920 --> 00:27:17,720
Speaker 1: have found ways to print thin film solar cells by

462
00:27:17,800 --> 00:27:22,920
Speaker 1: spraying and and ink made with these materials onto foil UM,

463
00:27:22,960 --> 00:27:25,879
Speaker 1: which is really cool because uh, it enables it to

464
00:27:25,920 --> 00:27:29,239
Speaker 1: be somewhat flexible, and you can use it in places, uh,

465
00:27:29,359 --> 00:27:32,040
Speaker 1: these types of solar cells in ways that you wouldn't

466
00:27:32,119 --> 00:27:35,679
Speaker 1: be able to otherwise. UM. Really you could see something

467
00:27:35,800 --> 00:27:40,880
Speaker 1: like this on a handheld calculator because those solar cells,

468
00:27:41,160 --> 00:27:44,360
Speaker 1: you know, the little itty bitty ones um, are thinner

469
00:27:44,720 --> 00:27:47,480
Speaker 1: than the ones that you see on on rooftops and

470
00:27:47,520 --> 00:27:51,200
Speaker 1: in different places like that. UM. The thing is they

471
00:27:52,760 --> 00:27:58,680
Speaker 1: they're about fifty efficient at maximum UM, which is more

472
00:27:58,760 --> 00:28:03,399
Speaker 1: likely to be more like fifty efficient UM, which is

473
00:28:03,440 --> 00:28:07,440
Speaker 1: of course also south of the efficiency that they strive

474
00:28:07,520 --> 00:28:10,960
Speaker 1: for with the uh, the silicon based wafer cells, the

475
00:28:11,040 --> 00:28:15,520
Speaker 1: hard cells. So you know, it's it's they're getting to

476
00:28:15,640 --> 00:28:18,239
Speaker 1: be more of a reality. This is something that's been

477
00:28:18,240 --> 00:28:22,080
Speaker 1: in development for several years now, UM, and they're you're

478
00:28:22,080 --> 00:28:25,320
Speaker 1: seeing them in more places. But they also have their drawbacks,

479
00:28:25,920 --> 00:28:27,919
Speaker 1: you know, and you know there are other drawbacks with

480
00:28:27,960 --> 00:28:30,520
Speaker 1: solar panels as well. The efficiency is a big one,

481
00:28:30,600 --> 00:28:35,720
Speaker 1: because the less efficient a solar array is, the more

482
00:28:36,280 --> 00:28:38,360
Speaker 1: cells you're going to need in order to generate the

483
00:28:38,360 --> 00:28:43,080
Speaker 1: electricity you want. Right you and in general big areas

484
00:28:43,120 --> 00:28:45,480
Speaker 1: to get a lot of sun. That's that's your prime

485
00:28:46,280 --> 00:28:51,080
Speaker 1: target for any sort of solar power facility. Um, you know,

486
00:28:51,120 --> 00:28:55,360
Speaker 1: it's it's one thing to put solar cells over the

487
00:28:55,400 --> 00:28:58,440
Speaker 1: roof of your house, is very difficult to generate enough

488
00:28:58,440 --> 00:29:03,440
Speaker 1: power to actually uh be completely subsist just on on

489
00:29:03,480 --> 00:29:06,120
Speaker 1: solar power. For one thing, if you're if it's if

490
00:29:06,160 --> 00:29:08,320
Speaker 1: you're using the power as soon as it's generated, then

491
00:29:08,320 --> 00:29:10,080
Speaker 1: you're only going to be able to use power during

492
00:29:10,080 --> 00:29:12,440
Speaker 1: the day and on a sunny day at that, right,

493
00:29:12,480 --> 00:29:14,760
Speaker 1: So you're gonna have to have batteries, some sort of

494
00:29:14,800 --> 00:29:18,760
Speaker 1: storage medium in order to h to store power and

495
00:29:18,840 --> 00:29:21,800
Speaker 1: use it later. And just frankly, I don't think there

496
00:29:21,840 --> 00:29:25,120
Speaker 1: are that many houses that are have enough efficient solar

497
00:29:25,160 --> 00:29:30,040
Speaker 1: panels to just rely on solar energy and battery backup. Now,

498
00:29:30,120 --> 00:29:34,000
Speaker 1: there are some and in fact, I've I've heard stories

499
00:29:34,040 --> 00:29:36,840
Speaker 1: about people who are still connected to the electricity grid

500
00:29:36,880 --> 00:29:41,760
Speaker 1: who are using solar power predominantly in their houses and um,

501
00:29:41,880 --> 00:29:44,719
Speaker 1: and in some cases if they generate more electricity than

502
00:29:44,760 --> 00:29:49,200
Speaker 1: they are consuming, they can actually feed energy back into

503
00:29:49,240 --> 00:29:52,520
Speaker 1: the grid and their power company will compensate them for

504
00:29:52,560 --> 00:29:56,160
Speaker 1: that much. Is a nice benefit, especially because these solar

505
00:29:56,280 --> 00:29:59,560
Speaker 1: arrays can be very expensive to install, right And usually

506
00:29:59,560 --> 00:30:02,560
Speaker 1: that only I mean, if you are in the right

507
00:30:02,680 --> 00:30:04,880
Speaker 1: area and you've got the right kind of solar cells,

508
00:30:04,920 --> 00:30:07,520
Speaker 1: then you may actually make enough where you're making money

509
00:30:07,560 --> 00:30:10,840
Speaker 1: from the power company. But more often it's a reduction

510
00:30:10,920 --> 00:30:13,040
Speaker 1: in your power bill. Like, first of all, your power

511
00:30:13,040 --> 00:30:14,720
Speaker 1: bill is not gonna be that high anyway, because you're

512
00:30:14,720 --> 00:30:18,240
Speaker 1: mostly relying on the solar cells and the power company

513
00:30:18,320 --> 00:30:22,760
Speaker 1: is providing whatever amount left over you require. But then

514
00:30:22,760 --> 00:30:26,000
Speaker 1: occasionally you produce more than what you need, uh, so

515
00:30:26,040 --> 00:30:28,240
Speaker 1: your bill will just be lower at the end. Yeah,

516
00:30:28,320 --> 00:30:31,240
Speaker 1: it's not like your you can recoup your investment overnight

517
00:30:31,480 --> 00:30:34,560
Speaker 1: or over sunny day, right especially. Yeah, and if you

518
00:30:34,600 --> 00:30:38,000
Speaker 1: happen to have a stretch of time where it's just

519
00:30:38,200 --> 00:30:41,080
Speaker 1: overcast day after day after day, then that those are

520
00:30:41,120 --> 00:30:43,920
Speaker 1: days when you're not really gonna be producing that much power. Um.

521
00:30:44,040 --> 00:30:46,760
Speaker 1: Not to say that it isn't worthwhile, no, but it

522
00:30:47,000 --> 00:30:49,600
Speaker 1: you know, don't expect you know, to make it back

523
00:30:49,680 --> 00:30:55,880
Speaker 1: up immediately. And another difficulty is that some depending on

524
00:30:55,920 --> 00:30:58,040
Speaker 1: the materials that are going into those solar panels, they

525
00:30:58,040 --> 00:31:02,520
Speaker 1: may or may not be either rare earth metals, which

526
00:31:02,680 --> 00:31:05,040
Speaker 1: there there's a whole host of problems. We if you've

527
00:31:05,040 --> 00:31:09,280
Speaker 1: heard O our podcast on rare earth materials, then you

528
00:31:09,320 --> 00:31:11,600
Speaker 1: know you know that that has its own host of

529
00:31:11,720 --> 00:31:15,600
Speaker 1: issues as well. Uh. There's also the possibility of depending

530
00:31:15,600 --> 00:31:17,959
Speaker 1: on again on the material in the solar cell, there

531
00:31:18,000 --> 00:31:21,040
Speaker 1: may be very toxic material in there, or material that

532
00:31:21,080 --> 00:31:24,440
Speaker 1: may not it'sself be toxic, but the manufacturing process of

533
00:31:24,480 --> 00:31:29,920
Speaker 1: that material itself produces toxic toxic materials. So there is

534
00:31:30,000 --> 00:31:34,600
Speaker 1: the potential for solar power to do environmental harm indirectly.

535
00:31:35,000 --> 00:31:39,640
Speaker 1: You know, the actual production of electricity isn't environmentally destructive,

536
00:31:39,960 --> 00:31:44,600
Speaker 1: but the process of building those solar panels itself maybe.

537
00:31:45,200 --> 00:31:47,520
Speaker 1: So you have to look at the big picture and

538
00:31:47,560 --> 00:31:51,160
Speaker 1: the full impact of the system. You can't just look

539
00:31:51,200 --> 00:31:53,200
Speaker 1: at Hey, you know, I'm getting energy from the sun.

540
00:31:53,320 --> 00:31:57,440
Speaker 1: I'm not burning any fossil fuels. Uh, this is clean energy.

541
00:31:57,680 --> 00:32:00,880
Speaker 1: Everything's hunky dorry. You have to look beyond that in

542
00:32:01,000 --> 00:32:05,280
Speaker 1: order to really consider the impact of the system. Yeah,

543
00:32:05,360 --> 00:32:08,240
Speaker 1: which you know that mean eventually get to a point

544
00:32:08,280 --> 00:32:09,960
Speaker 1: where you're looking at it from such a big picture

545
00:32:10,080 --> 00:32:15,400
Speaker 1: that you're thinking there's no solutions out there. Goodnight kids. Well,

546
00:32:15,440 --> 00:32:17,800
Speaker 1: I think, uh, well, we've sort of talked about it

547
00:32:17,840 --> 00:32:21,280
Speaker 1: another podcast to like the bloom Box and other other things.

548
00:32:21,280 --> 00:32:23,800
Speaker 1: But yeah, I mean it's it's one of those things

549
00:32:23,800 --> 00:32:26,480
Speaker 1: where in the long run, I think it's a it's

550
00:32:26,480 --> 00:32:29,200
Speaker 1: gonna end up being a combination of solutions, you know,

551
00:32:29,320 --> 00:32:33,360
Speaker 1: to get off of fossil fuels, rather than just a single, uh,

552
00:32:33,520 --> 00:32:36,280
Speaker 1: you know, single one. I think it will probably involve

553
00:32:36,320 --> 00:32:39,280
Speaker 1: jackostile terriers on a treadmill. It might, and it might

554
00:32:39,400 --> 00:32:41,560
Speaker 1: very well, because as far as I can tell, they

555
00:32:41,560 --> 00:32:45,360
Speaker 1: have an inexhaustible supply of energy. Yeah, especially if you

556
00:32:45,480 --> 00:32:47,720
Speaker 1: if you, you know, have a treat at the end

557
00:32:47,760 --> 00:32:52,880
Speaker 1: of the the little conveyor belt, they'll just run, run, run, anyway,

558
00:32:53,120 --> 00:32:55,400
Speaker 1: that's neither here nor there. Well, that was a great

559
00:32:55,440 --> 00:32:59,480
Speaker 1: discussion about solar panel technology. I hope that answered your question, Adam. Uh,

560
00:32:59,600 --> 00:33:03,800
Speaker 1: it was a fun things topic to cover and uh, well,

561
00:33:04,240 --> 00:33:06,640
Speaker 1: if you guys have suggestions for topics that you would

562
00:33:06,680 --> 00:33:09,360
Speaker 1: like us to talk about, feel free to let us know.

563
00:33:09,680 --> 00:33:12,960
Speaker 1: You can contact us on Twitter or Facebook. Our handle

564
00:33:13,040 --> 00:33:16,760
Speaker 1: at both of those is text Stuff hs W. Or

565
00:33:16,840 --> 00:33:19,080
Speaker 1: you can send us an email and that address is

566
00:33:19,360 --> 00:33:22,760
Speaker 1: text Stuff at how stuff Works dot com and Chris

567
00:33:22,800 --> 00:33:27,240
Speaker 1: and I will talk to you again really soon. Be

568
00:33:27,360 --> 00:33:29,960
Speaker 1: sure to check out our new video podcast, Stuff from

569
00:33:30,000 --> 00:33:32,840
Speaker 1: the Future. Join how Stuff Work staff as we explore

570
00:33:32,880 --> 00:33:37,440
Speaker 1: the most promising and perplexing possibilities of tomorrow. The How

571
00:33:37,480 --> 00:33:41,240
Speaker 1: Stuff Works iPhone app has arrived. Download it today on iTunes,

572
00:33:45,800 --> 00:33:48,400
Speaker 1: brought to you by the reinvented two thousand twelve camera.

573
00:33:48,720 --> 00:33:49,880
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