Speaker 1: Brought to you by the reinvented two thousand twelve camera.
Speaker 1: It's ready. Are you hey there, Text Stuff listeners, This
Speaker 1: is Jonathan Strickland and I have got a request for
Speaker 1: all of you. Now, Chris and I have decided that
Speaker 1: we're going to try and experiment. We're doing our first
Speaker 1: crowd sourced episode of tech Stuff and we want to
Speaker 1: know what your pick is for the worst video game
Speaker 1: of all time. Now, nominations you can. You can make
Speaker 1: one nomination. You nominate one game, and you need to
Speaker 1: tell us the name of the game and the platform
Speaker 1: it was on. And it could be any platform. It
Speaker 1: could be an arcade game, it could be a PC, Mac, Xbox,
Speaker 1: PS three, Nintendo handheld console. It can be web based
Speaker 1: if you like. But just you let us know what
Speaker 1: the platform is so we can make sure we count
Speaker 1: that as the votes. So you can nominate your game
Speaker 1: either through email, which is tech Stuff at how stuff
Speaker 1: works dot com, or you can nominate through Twitter or Facebook.
Speaker 1: And we're gonna put a cut off date on this.
Speaker 1: I want to have the episode go up by the
Speaker 1: end of September of eleven. So let's say you need
Speaker 1: to get your nominations in by September eleven, So if
Speaker 1: you get those nominations into us, we will make sure
Speaker 1: we include those in the process and we will have
Speaker 1: an episode where we give you the worst video games
Speaker 1: of all time based upon the votes of our listeners.
Speaker 1: Thanks a lot. Can't wait to hear from you. Get
Speaker 1: in touch with technology with tech Stuff from how stuff
Speaker 1: works dot com. Hello, everyone, Welcome to tech Stuff. My
Speaker 1: name is Chris Poet and I am an editor at
Speaker 1: how stuff works dot com. Sitting across from me as
Speaker 1: always and for some reason twisting up a rubber dinosaur
Speaker 1: is senior writer Jonathan Strickland, Little Darlin, the smiles returning
Speaker 1: to the faces, Little Darling, it seems like years since
Speaker 1: it's been here. H. That was a nice choice for
Speaker 1: today's topic, which is I think something that everyone will
Speaker 1: find electrifying. Yeah, and in fact, this comes to us
Speaker 1: courtesy of a Google Plus suggestion. This comes from Adam,
Speaker 1: who says this may be a bit simple, but have
Speaker 1: you guys ever done an overview of solar technology and
Speaker 1: solar tech history? Just re listened to your battery podcast
Speaker 1: and it made me wonder more about alternative energy sources. Adam, um,
Speaker 1: your definition of simple and my definition of simple are
Speaker 1: too very different things. But but yeah, we're gonna talk
Speaker 1: about solar power, solar cells also known as photo voltaic cells,
Speaker 1: and uh kind of where it came from. M Yeah,
Speaker 1: they're not they're certainly not new. UM. We have an
Speaker 1: article about how solar cells work on the website UM
Speaker 1: which discusses how they were used in the nineteen fifties
Speaker 1: in space uh space technology. Yeah. In fact, the well,
Speaker 1: to go back even further, the photoelectric effect, which of
Speaker 1: course is the basis of photovoltaic fells, that was first
Speaker 1: discovered by a or at least first observed by a
Speaker 1: French physicist named Edmund Beckerel. It's an eighteen thirty nine. Wow,
Speaker 1: that was some time ago. Yeah. Now, granted he observed
Speaker 1: that certain materials, if if exposed to sunlight, would produce
Speaker 1: a certain amount of electric current, but there wasn't really
Speaker 1: any way of putting that to any use at the time.
Speaker 1: It was just it was an interesting scientific observation and
Speaker 1: that was the the limit of it. Einstein himself began
Speaker 1: to ruminate on this, decided about, you know, to kind
Speaker 1: of think about what is the nature of light, how
Speaker 1: does it interact with the nature of electricity, what's the
Speaker 1: relationship there? Um? And then he actually won a Nobel
Speaker 1: Prize based on his observations. Now, the first module photo
Speaker 1: vote vol take module, because a module is a collection
Speaker 1: of photo voltaic cells. In fact, we can get this
Speaker 1: out of the way and really early on, if you
Speaker 1: want to talk about like the a sense of scale,
Speaker 1: an individual photo voltaic cell, when grouped together with other
Speaker 1: photo voltaic cells, makes a module, and groups of modules
Speaker 1: together make an array. So it's just it's just as
Speaker 1: a question of scale. So array isn't a group of
Speaker 1: modules and modules a group of photo photo voltaic cells.
Speaker 1: I'm gonna stumble over that over and over in this episode,
Speaker 1: so I hope you guys are listening at twice speed
Speaker 1: so that the chipmunk is messing up over and over
Speaker 1: and not me. Anyway. The first module was built by
Speaker 1: Bell Laboratories, and that was in nineteen fifty four. And uh,
Speaker 1: at that point they were thinking of it kind of
Speaker 1: they think they called it a solar battery. They didn't
Speaker 1: even call it a solar cell at that point, and
Speaker 1: it was kind of considered to be an interesting idea
Speaker 1: but not at all practical. I think they determined that
Speaker 1: based upon the amount of work and uh it took
Speaker 1: to develop and manufacture that first module. They were getting
Speaker 1: about a watt for every I think it's two fifty
Speaker 1: bucks per what, which is not efficient doesn't even compare
Speaker 1: to other materials at all. Right, So not something that
Speaker 1: they could implement immediately in order to to try and
Speaker 1: generate electricity. And and then later on the fifties and
Speaker 1: then into the sixties, really primarily in the sixties, that's
Speaker 1: when the space industry began to use these solar cells
Speaker 1: in order to get power for vehicles that be traveling
Speaker 1: through space and also satellites that would be placed in
Speaker 1: orbit around the Earth. You know, you have to have
Speaker 1: power going to these satellites somehow, and you know, batteries
Speaker 1: can provide power, but power batteries will die out and
Speaker 1: there's no way of recharging easily when you can't tether
Speaker 1: the device to the Earth. Okay, spot Nick, enough of that. Um. So,
Speaker 1: solar cells were a way to be first for satellites
Speaker 1: to gather power and remain in orbit functioning properly for longer.
Speaker 1: Um Now, why are we even talking about solar power
Speaker 1: in the first place. Well, mainly because it's abundant, and
Speaker 1: one would imagine inexpensive. I mean, you've got about a
Speaker 1: thousand watts of energy per square meter of the planet's surface. Yeah,
Speaker 1: that's a lot of energy. Uh. You know, the Sun
Speaker 1: shoots out lots of lots of energy towards the Earth.
Speaker 1: I mean, really, the Sun shoots out lots of energy everywhere,
Speaker 1: but we on Earth are happy to receive quite a
Speaker 1: bit of it. Uh and we some of it gets
Speaker 1: absorbed in the atmosphere, some of it gets absorbed by
Speaker 1: the surface of the Earth, some of it is converted
Speaker 1: into energy via photosynthesis by the agitation, and then the
Speaker 1: rest of it just kind of gets reflected back off
Speaker 1: into space. So there's all this energy that is not
Speaker 1: being used in any meaningful way at all, and it's
Speaker 1: just it's going away. And uh So the thought is
Speaker 1: using solar cell technology, we could perhaps harness some of
Speaker 1: this energy that otherwise we would just lose um. And
Speaker 1: that's the basis behind the the push for solar energy. Now,
Speaker 1: the engineering challenges that face us as we try to
Speaker 1: actually harness that power are what kind of keep us
Speaker 1: from just adopting it wholesale. That and also, I mean
Speaker 1: there's some practical problems besides the engineering issues. Right, Like,
Speaker 1: if you live in a place where there's not a
Speaker 1: lot of you don't get a lot of sun, then
Speaker 1: solar energy doesn't make a whole lot of sense. It
Speaker 1: would be a lot it would be a heavy investment
Speaker 1: for very little payoff. Um. Now, if you live in
Speaker 1: a place that tends to get sun most of the error,
Speaker 1: than solar cells make a lot more sense. Yeah. The
Speaker 1: basics involve something that we've talked about many times in
Speaker 1: the show. Semiconductors, which is a material that allows some
Speaker 1: electrons to flow, but not all the available electrons to flow,
Speaker 1: permits some flow of electricity, but not there's some control, right.
Speaker 1: It acts somewhat like a conductor and somewhat like an insulator.
Speaker 1: And uh and and it's the relationship between the semiconductor
Speaker 1: and photons, which are the particles that we can you know,
Speaker 1: units of light energy really because you talk about how
Speaker 1: light can be both a wave and a particle, but
Speaker 1: really talk about a photon having a certain amount of
Speaker 1: energy um. And the energy has to be enough to
Speaker 1: cause the semiconductor to conduct electricity. And I guess we
Speaker 1: can get into how that works and the basis behind that,
Speaker 1: and uh really comes down to things like a selah
Speaker 1: common crystals. Yeah, yeah, well it's possible. I should say
Speaker 1: upfront that it's not always silicon. That's true, silicon being
Speaker 1: the predominant material it's used. I think for the purposes
Speaker 1: of of this early part of the discussion, I think
Speaker 1: we should think of the solar cells that you see
Speaker 1: mounted on roofs and different places, because those are the
Speaker 1: ones with which most of us are familiar. So, yeah,
Speaker 1: the dominant semiconductor used in that as silicon. Right, So
Speaker 1: in order to understand how the solar cells work, we're
Speaker 1: gon we're gonna have to take a little a little
Speaker 1: chemistry lesson here and learn more about silicon itself. So,
Speaker 1: silicon is an atom that has fourteen electrons. Yea. There
Speaker 1: are three different shells um and the first two are
Speaker 1: are full. There are two and eight electrons, but uh
Speaker 1: the outer shell has room for eight, but generally only
Speaker 1: has four. So, uh, you know the shells case you
Speaker 1: don't remember, the shells are essentially they represent a general
Speaker 1: space around the nucleus of the atom where electrons are
Speaker 1: capable of existing. And because electrons are negatively charged and
Speaker 1: and like charge, Uh, what's the word thank you? It
Speaker 1: just escaped repulse to repelled? Yes, that those those sometimes
Speaker 1: they away from thank you. Yeah. I was like, I
Speaker 1: think they don't like each other. And I was like,
Speaker 1: that's probably not quite as sophisticated as our listeners expect,
Speaker 1: well they expected from me. You're so so like like
Speaker 1: charges repel one another, Thank you, Mr Palette. Without you,
Speaker 1: I would have just been sitting here quiet and Matt
Speaker 1: would have been snickering in the other room. Space is
Speaker 1: getting really read. It was really entertining, you know, it
Speaker 1: happens sometimes my brain just gives out on me. So, yes,
Speaker 1: light getting back to it like charge repels like so, so,
Speaker 1: these electron shells represent a space where electrons are capable
Speaker 1: of existing, and you can't have more electrons in that
Speaker 1: space because the negative charges would push push the electrons out.
Speaker 1: So then the second shell, that's the one where you
Speaker 1: can have up to eight electrons there, and then the
Speaker 1: third shell, up to eight can exist there, but only
Speaker 1: four are there in a in a silicon atom, So
Speaker 1: if you you know, there's room for more electrons there.
Speaker 1: In a way, I hesitate to use the word want
Speaker 1: because it's just sentience. But it's it's these atoms are not,
Speaker 1: as far as we know, sentient in any way, tend
Speaker 1: to Yeah, they there is a a there's a tendency
Speaker 1: for these atoms to require more electrons in that final
Speaker 1: shell to have a full outer shell. Right, that's that's
Speaker 1: the goal of these atoms, as if there were like
Speaker 1: some sort of conscious goal. So, so when you get
Speaker 1: a whole lot of silicon atoms together, they tend to
Speaker 1: bond together, um because they begin to share electrons in
Speaker 1: their outer shells, and so they get really really tight.
Speaker 1: So a silicon atom will bond with four other silicon
Speaker 1: atoms to fill up that outer shell. And each of
Speaker 1: those silicon atoms are bonding to up with up to
Speaker 1: four other silicon itoms to fill up their outer shell,
Speaker 1: and this creates a crystalline structure, and they bond with
Speaker 1: four friends and so on and so on. So, yeah,
Speaker 1: you get this crystalline structure. Now, once you have this,
Speaker 1: we're talking right now about a pure silicon crystalline structure, right,
Speaker 1: So when you get all these these outer shells full
Speaker 1: of electrons, there's a problem and that it doesn't really
Speaker 1: conduct electricity at that point because you don't have any
Speaker 1: free electrons, free raining electrons to uh to move through
Speaker 1: that material. So if you introduce electricity, it's hard. It
Speaker 1: takes a lot more energy to break the electrons out
Speaker 1: of those bonds so that they will flow through. If
Speaker 1: you you can do it, but you have to put
Speaker 1: a lot of energy into the system. Yeah. What you're
Speaker 1: looking for here is free carriers, the electrons that are
Speaker 1: wandering around. Um. That will allow you to conduct electricity.
Speaker 1: You know, if there are a lot of them. Um.
Speaker 1: So what you have to do next is really dope. Yeah, yeah,
Speaker 1: you have to dope the silicon. Now that means that
Speaker 1: you are introducing impurities or other elder ingredients if you will,
Speaker 1: into the silicon crystal. So you know when you think
Speaker 1: about impurities and usually that has a negative connotation to it,
Speaker 1: but in this case, it's something that's really necessary you
Speaker 1: can put there. Now, there are two different routes to go, right.
Speaker 1: You can put in atoms into You can introduce atoms
Speaker 1: into this mixture that have more electrons in their elder
Speaker 1: shell than silicon does. Now, that's going to introduce extra
Speaker 1: electrons into this crystall instructures. Some electrons that are not
Speaker 1: bonded with other atoms. So that's where you've got these
Speaker 1: free carriers, and then it doesn't take as much energy
Speaker 1: when you introduce energy into the system to break those
Speaker 1: electrons free from the structure. UM, it's still requires energy
Speaker 1: because they're the those electrons are still attracted to the um,
Speaker 1: the positively charged nucleus, but it doesn't take as much
Speaker 1: as if all the atoms were bonded to one another
Speaker 1: with no free electrons. Yeah, if you used, for example,
Speaker 1: phosphorus and uh introduced that to pure silicon, first of all,
Speaker 1: they would really hit it off at the party. Yes.
Speaker 1: Oh wait, I'm thinking of introducing in a totally different
Speaker 1: way anyway. So if you dope some pure silicon with
Speaker 1: with phosphorus um, you would add you would essentially be
Speaker 1: adding free electrons or source of free electrons, let's say that,
Speaker 1: and that would create an end type uh semiconductor and
Speaker 1: meaning negative because again, electrons have a negative charge, so
Speaker 1: you've actually got more of a negative charge than a
Speaker 1: positive charge because you have these extra electrons. Uh. Now, now,
Speaker 1: if you were to introduce a material that had fewer
Speaker 1: electrons in its outer shell than silicon, you would end
Speaker 1: up with spaces for electrons where no electrons exist. That
Speaker 1: would be a P type of silicon, yes, because you
Speaker 1: would have a space for electrons, but there would be
Speaker 1: no electron to fill that space. Now, if you were
Speaker 1: to take these two types of silicon, the N type
Speaker 1: and the P type and put them together, then the
Speaker 1: like the extra electrons from the N type want to
Speaker 1: go and again want being just they tend to go
Speaker 1: to the P type because there's a positive hole there
Speaker 1: and you have the negative charged electrons in the N type.
Speaker 1: So there's this immedia desire to transfer or tendency to transfer.
Speaker 1: Chris is just laughing because I'm adding anthropomorphiz sizing electrons. Look,
Speaker 1: some of my best friends are free carriers. Okay, hey,
Speaker 1: let's go to the P type. Oh, man, is too early.
Speaker 1: I didn't want to see the animated version of this.
Speaker 1: Little know, the electrons with little faces drawn on a
Speaker 1: big smile. Hey, so you got a hole there? I
Speaker 1: can feel that. So the uh yeah, there's this tendency
Speaker 1: for the electrons to move across. Well, this creates this
Speaker 1: actually can create a barrier that acts like a diode.
Speaker 1: And if you've listened to our Basic Electronics podcast, you
Speaker 1: know that a diode is this channel that allows electricity
Speaker 1: to flow one way but not back in the other
Speaker 1: directions one way street exactly. And in this case, interestingly enough,
Speaker 1: it will allow electrons to transfer from the PA side
Speaker 1: to the inside, but not the other way around. Oh yeah,
Speaker 1: so because that's not what they normally want to do, right.
Speaker 1: So now this is where we finally get into introducing
Speaker 1: photons into this system. All right, So you've got this,
Speaker 1: You've got the system here where you've got this barrier
Speaker 1: between the N type selicon and the B type cell
Speaker 1: con and you've got the potential for electrons to move
Speaker 1: across this barrier if you introduce energy into the system,
Speaker 1: and the photons are that energy. So when a photon
Speaker 1: of a proper amount of energy strikes the silicon, UH,
Speaker 1: it can create enough energy for the electrons to transfer
Speaker 1: across this barrier. Now, once the electrons cross cross that
Speaker 1: barrier from the P type to the ND type UH,
Speaker 1: they are now in a negatively charged environment, so that
Speaker 1: the tendency is for these electrons to try and get
Speaker 1: back to the positively charged environment, but they can't pass
Speaker 1: that barrier. So if you were to create a pathway
Speaker 1: from the negative side to the positive side. The electrons
Speaker 1: would follow that pathway and do whatever it was you
Speaker 1: wanted them to do if it meant they could get
Speaker 1: to the positive side on the other end. So it's other.
Speaker 1: In other words, it's like a really exclusive party and
Speaker 1: you're like, Okay, you can come into the party, but
Speaker 1: you gotta carry my stuff into the room with you.
Speaker 1: And people want to get the party, You're like that totally.
Speaker 1: The party is worth it. I will carry your stuff.
Speaker 1: That's kind of the the analogy I'm going with here.
Speaker 1: There's a party I want to go to tonight. Did
Speaker 1: I mention that anyway? So, so do you do you
Speaker 1: have to power somebody's computer to do it? No? Fortunately not.
Speaker 1: So the electrons will do work along this pathway. And
Speaker 1: that's just a basic circuit, right, it's a and it's
Speaker 1: it allows current to flow. So photon hits the silicon
Speaker 1: uh and as long as the photon has enough energy
Speaker 1: to break that bond, the electron goes across the barrier,
Speaker 1: wants to get back to the pea side, will go
Speaker 1: through this pathway to get back to the peace side,
Speaker 1: and along the way will do work. So that work
Speaker 1: might be lighting a light bulb. That's the basic example
Speaker 1: that you see in most uh sure drawings. So that's
Speaker 1: that's the basic principle. Now we gotta address a couple
Speaker 1: of other minor points to actually play a big role
Speaker 1: in in y solar cells work and why they aren't
Speaker 1: as um why we don't see them everywhere right now, Yeah,
Speaker 1: you mean, like, um, the fact that, well there are
Speaker 1: other components to the solar cells to sure how light
Speaker 1: bounces off stuff like silicon. Right, Silicon tends to be
Speaker 1: very shiny, which means that some photons when they strike
Speaker 1: the surface are just going to reflect off and not
Speaker 1: get absorbed at all, which is a problem. If you're
Speaker 1: not absorbing the energy, then you cannot, um, you don't
Speaker 1: have enough energy for the electrons to break free by
Speaker 1: the way, that that we call that the band gap energy,
Speaker 1: to to break free of that that final electron shell.
Speaker 1: So one problem is that not all photons have the
Speaker 1: same amount of energy because light comes in a variety
Speaker 1: of forms. You know, we talked about the spectrum of light.
Speaker 1: So you know, you can see light like visible light
Speaker 1: and has a pretty wide spectrum, but even beyond that
Speaker 1: is an even wider spectrum infrared light, ultraviolet light, and
Speaker 1: then you know of course all the different colors. Well,
Speaker 1: each of those types of of light have a different
Speaker 1: amount of energy, and if the energy is not sufficient
Speaker 1: to UH to overcome the band gap energy, the electron
Speaker 1: is not going anywhere. So if the energy is more
Speaker 1: than what the band gap needs, that electron will move,
Speaker 1: but some of that energy is wasted. Like for example,
Speaker 1: if I need if I can lift a hundred and
Speaker 1: ten pounds and there's a weight in front of me
Speaker 1: that's a hundred pounds, I can lift that up. But
Speaker 1: if there are two weights that are a hundred pounds,
Speaker 1: I'm still only gonna be able to lift one up.
Speaker 1: Even though I'm capable of lifting over a hundred pounds,
Speaker 1: I'm not capable of lifting two hundred pounds. So if
Speaker 1: you get a photon that actually has say twice as
Speaker 1: much energy as the band gap energy, then you could
Speaker 1: actually move to electrons per photon UM. So that's another problem.
Speaker 1: So how do we get past the reflective problem? Well,
Speaker 1: usually they get around it by putting on some kind
Speaker 1: of material that is an anti reflective property, um, just
Speaker 1: to keep the photons from bouncing away UM. And that
Speaker 1: that's one thing they have to do. They also have
Speaker 1: to put a cover plate on it, you know, glass,
Speaker 1: essentially to keep the solar cell from being damaged. Because
Speaker 1: again we were talking about the solar cells that you
Speaker 1: see the arrays that you see in on rooftops and
Speaker 1: um and for in some instances on the side of
Speaker 1: the I see a lot of them on the side
Speaker 1: of the road where they have some kind of equipment there, um,
Speaker 1: you know, a sign or something that they want to
Speaker 1: use to uh, you know, to provide messages to people
Speaker 1: who are traveling on the roadway. They'll have a giant
Speaker 1: or not a giant, but a large solar panel out
Speaker 1: there to help power the sign. Um. You know, that's
Speaker 1: sitting out there all the time, so you know, you
Speaker 1: don't want it to be damaged by the rain or
Speaker 1: or anything. Um, So you know, you have to have
Speaker 1: these other things that are they're going on. But unfortunately,
Speaker 1: these uh, these solar cells are not particularly efficient. Yeah,
Speaker 1: there's actually there's several reasons why efficiency is a problem.
Speaker 1: One of those is, you know, I mentioned the whole
Speaker 1: band gap energy problem. Whereas one temptation would be to
Speaker 1: build a solar cell that be able to gather as
Speaker 1: many photons as possible. In other words, aim for the
Speaker 1: lowest common denominator, like create material that's going to have
Speaker 1: the lowest band gap energy, so that even weak photons
Speaker 1: would be able to make electrons flow. Well, here's the
Speaker 1: problem with that. Current is that would be the number
Speaker 1: of electrons that move through a system. Right, But there's
Speaker 1: another element called voltage, and and voltage is more like
Speaker 1: if you want to think of it in terms of plumbing,
Speaker 1: voltage would be the pressure and current would be the
Speaker 1: amount of water um. So voltage and current together, When
Speaker 1: you combine the two together, you get power. That's the
Speaker 1: product of current and voltage. So you mustapply the two
Speaker 1: and you get power. So the power from any system
Speaker 1: is going to be dependent upon the current and the voltage.
Speaker 1: If you use material that has a low band gap energy,
Speaker 1: you get a lower voltage in that system, so you've
Speaker 1: actually decreased the voltage. So the current increases, but the
Speaker 1: voltage decreases, so the product does not necessarily become enough
Speaker 1: for it to be a good return on investment. So,
Speaker 1: in other words, you could create something that creates has
Speaker 1: more current but a lower voltage, the power is less.
Speaker 1: It does it doesn't do as much work as say,
Speaker 1: materials that have a higher band gap energy, even though
Speaker 1: you've even though you are discounting more photons in that
Speaker 1: in that other system, the photons that are hitting are
Speaker 1: producing more energy. UM. So that's one issue. Although you
Speaker 1: can kind of work around that in a way. You
Speaker 1: can create a multi junction cell. And a multijunction cell
Speaker 1: is uh. You can think of that as layers of
Speaker 1: cells on top of one another, and one layer has
Speaker 1: a certain band gap energy, and then the next one
Speaker 1: has a different band gap energy, and the next one
Speaker 1: has yet another band gap energy. In order to capture
Speaker 1: as many of these photons as possible, and that will
Speaker 1: help a little bit. So that's one way you can
Speaker 1: do it. It's a very expensive thing to do, but
Speaker 1: NASA has been doing it for years. That's that's what
Speaker 1: NASA solar cells tend to be, our multi junction cells
Speaker 1: because you know, you want to you want the satellites
Speaker 1: to last a really long time so um, and you
Speaker 1: want them to be very efficient. But that's one problem
Speaker 1: with efficiency. Another is just the design of the solar
Speaker 1: cells themselves. In order for these electrons to hit a
Speaker 1: pathway a circuit, you know, they have to they have,
Speaker 1: you have to create that pathway for them, and that
Speaker 1: raises some challenges. Where do you put how do you
Speaker 1: create this pathway the top of the solar cell. It's
Speaker 1: hard to make a conductive layer, right, because I mean
Speaker 1: usually we tend to use metal. Metal is a good conductor.
Speaker 1: Most metals are good conductors. Yeah, and the series resistance
Speaker 1: of silicon is so high that it causes a lot
Speaker 1: of loss. Mean, if you're using something like copper, right,
Speaker 1: it would do great. Yeah, but copper doesn't have that
Speaker 1: photovoltaic quality. There's the problem. So if you're using metal
Speaker 1: to conduct the electricity, to act as the circuit, to
Speaker 1: act as the pathway for these electrons, um, the question is, well,
Speaker 1: you can't really, you can't encase it in metal because
Speaker 1: if you did, then no photons would get through. There
Speaker 1: has to be at least one side open. You know,
Speaker 1: you can create some conductive material that is, uh, you can,
Speaker 1: you can weave through the glass. But there's also a
Speaker 1: concern that you know, photons are these tiny, tiny, tiny particles,
Speaker 1: and even the thinnest metal material that might make up
Speaker 1: a grid in a solar module, for example, will block
Speaker 1: some electron photons. Rather which means that you're losing efficiency
Speaker 1: that way. So that's that's one of the reasons why
Speaker 1: solar panels can have problems with efficiency is that just
Speaker 1: based on the design itself, in order to conduct those
Speaker 1: electrons and provide electricity, you're blocking off some of the photons.
Speaker 1: So you're never going to get a hundred percent efficiency
Speaker 1: because just based on the technology itself, it's blocking its
Speaker 1: own source of power. That's frustrating. Photons just shake. Yeah,
Speaker 1: So they've been working on trying other types of materials, uh,
Speaker 1: stuff like a morphous silicon, cadmium tell your ide and
Speaker 1: copper iridium, gallium decelenide. Had some of that the other day.
Speaker 1: It was delish, But yeah, I mean these are using
Speaker 1: these materials, uh, you know, they've they've been trying to
Speaker 1: find some advantages. One of those is that with some
Speaker 1: of those materials you can create a thinner material, a
Speaker 1: thinner panel or thinnel thinner cell, and they call them
Speaker 1: thin film solar cells. And basically, yeah, these are very
Speaker 1: neat because, um, a lot of the again the arrays
Speaker 1: that we had in our initial example are pretty solid.
Speaker 1: They don't they don't bend, and the thin film solar cells. Yes,
Speaker 1: they do break, but um. Actually a couple of companies
Speaker 1: have found ways to print thin film solar cells by
Speaker 1: spraying and and ink made with these materials onto foil UM,
Speaker 1: which is really cool because uh, it enables it to
Speaker 1: be somewhat flexible, and you can use it in places, uh,
Speaker 1: these types of solar cells in ways that you wouldn't
Speaker 1: be able to otherwise. UM. Really you could see something
Speaker 1: like this on a handheld calculator because those solar cells,
Speaker 1: you know, the little itty bitty ones um, are thinner
Speaker 1: than the ones that you see on on rooftops and
Speaker 1: in different places like that. UM. The thing is they
Speaker 1: they're about fifty efficient at maximum UM, which is more
Speaker 1: likely to be more like fifty efficient UM, which is
Speaker 1: of course also south of the efficiency that they strive
Speaker 1: for with the uh, the silicon based wafer cells, the
Speaker 1: hard cells. So you know, it's it's they're getting to
Speaker 1: be more of a reality. This is something that's been
Speaker 1: in development for several years now, UM, and they're you're
Speaker 1: seeing them in more places. But they also have their drawbacks,
Speaker 1: you know, and you know there are other drawbacks with
Speaker 1: solar panels as well. The efficiency is a big one,
Speaker 1: because the less efficient a solar array is, the more
Speaker 1: cells you're going to need in order to generate the
Speaker 1: electricity you want. Right you and in general big areas
Speaker 1: to get a lot of sun. That's that's your prime
Speaker 1: target for any sort of solar power facility. Um, you know,
Speaker 1: it's it's one thing to put solar cells over the
Speaker 1: roof of your house, is very difficult to generate enough
Speaker 1: power to actually uh be completely subsist just on on
Speaker 1: solar power. For one thing, if you're if it's if
Speaker 1: you're using the power as soon as it's generated, then
Speaker 1: you're only going to be able to use power during
Speaker 1: the day and on a sunny day at that, right,
Speaker 1: So you're gonna have to have batteries, some sort of
Speaker 1: storage medium in order to h to store power and
Speaker 1: use it later. And just frankly, I don't think there
Speaker 1: are that many houses that are have enough efficient solar
Speaker 1: panels to just rely on solar energy and battery backup. Now,
Speaker 1: there are some and in fact, I've I've heard stories
Speaker 1: about people who are still connected to the electricity grid
Speaker 1: who are using solar power predominantly in their houses and um,
Speaker 1: and in some cases if they generate more electricity than
Speaker 1: they are consuming, they can actually feed energy back into
Speaker 1: the grid and their power company will compensate them for
Speaker 1: that much. Is a nice benefit, especially because these solar
Speaker 1: arrays can be very expensive to install, right And usually
Speaker 1: that only I mean, if you are in the right
Speaker 1: area and you've got the right kind of solar cells,
Speaker 1: then you may actually make enough where you're making money
Speaker 1: from the power company. But more often it's a reduction
Speaker 1: in your power bill. Like, first of all, your power
Speaker 1: bill is not gonna be that high anyway, because you're
Speaker 1: mostly relying on the solar cells and the power company
Speaker 1: is providing whatever amount left over you require. But then
Speaker 1: occasionally you produce more than what you need, uh, so
Speaker 1: your bill will just be lower at the end. Yeah,
Speaker 1: it's not like your you can recoup your investment overnight
Speaker 1: or over sunny day, right especially. Yeah, and if you
Speaker 1: happen to have a stretch of time where it's just
Speaker 1: overcast day after day after day, then that those are
Speaker 1: days when you're not really gonna be producing that much power. Um.
Speaker 1: Not to say that it isn't worthwhile, no, but it
Speaker 1: you know, don't expect you know, to make it back
Speaker 1: up immediately. And another difficulty is that some depending on
Speaker 1: the materials that are going into those solar panels, they
Speaker 1: may or may not be either rare earth metals, which
Speaker 1: there there's a whole host of problems. We if you've
Speaker 1: heard O our podcast on rare earth materials, then you
Speaker 1: know you know that that has its own host of
Speaker 1: issues as well. Uh. There's also the possibility of depending
Speaker 1: on again on the material in the solar cell, there
Speaker 1: may be very toxic material in there, or material that
Speaker 1: may not it'sself be toxic, but the manufacturing process of
Speaker 1: that material itself produces toxic toxic materials. So there is
Speaker 1: the potential for solar power to do environmental harm indirectly.
Speaker 1: You know, the actual production of electricity isn't environmentally destructive,
Speaker 1: but the process of building those solar panels itself maybe.
Speaker 1: So you have to look at the big picture and
Speaker 1: the full impact of the system. You can't just look
Speaker 1: at Hey, you know, I'm getting energy from the sun.
Speaker 1: I'm not burning any fossil fuels. Uh, this is clean energy.
Speaker 1: Everything's hunky dorry. You have to look beyond that in
Speaker 1: order to really consider the impact of the system. Yeah,
Speaker 1: which you know that mean eventually get to a point
Speaker 1: where you're looking at it from such a big picture
Speaker 1: that you're thinking there's no solutions out there. Goodnight kids. Well,
Speaker 1: I think, uh, well, we've sort of talked about it
Speaker 1: another podcast to like the bloom Box and other other things.
Speaker 1: But yeah, I mean it's it's one of those things
Speaker 1: where in the long run, I think it's a it's
Speaker 1: gonna end up being a combination of solutions, you know,
Speaker 1: to get off of fossil fuels, rather than just a single, uh,
Speaker 1: you know, single one. I think it will probably involve
Speaker 1: jackostile terriers on a treadmill. It might, and it might
Speaker 1: very well, because as far as I can tell, they
Speaker 1: have an inexhaustible supply of energy. Yeah, especially if you
Speaker 1: if you, you know, have a treat at the end
Speaker 1: of the the little conveyor belt, they'll just run, run, run, anyway,
Speaker 1: that's neither here nor there. Well, that was a great
Speaker 1: discussion about solar panel technology. I hope that answered your question, Adam. Uh,
Speaker 1: it was a fun things topic to cover and uh, well,
Speaker 1: if you guys have suggestions for topics that you would
Speaker 1: like us to talk about, feel free to let us know.
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Speaker 1: you can send us an email and that address is
Speaker 1: text Stuff at how stuff Works dot com and Chris
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