Solar Energy

Solar Energy

The sun was humankind’s first source of
power, and, with a little work, may be the last one we’ll ever need. A good desert
collects more solar energy in six hours than the entire world uses in a year. The surface
area of my body is about, uh, a meter and a half squared. If I laid out in the sun all
day long every day for a year, I would collect about 1,500 watts of solar energy. And check
it out, pretty much all of the power that we as humans use originally was solar power.
And all coal is is the fossilized remains of plants and animals that died eons ago and
have been buried in the earth, and they got their energy from the sun. Natural gas and
oil, same thing, the sun. Nuclear power, which produces about 20% of our power, is one of
the two sources that we have that isn’t originally solar power, the other being tidal,
which is created by the moon. Hydroelectric power, how does that water get up in the mountains
so that it has to run down the rivers, well, it gets evaporated from the ocean by the sun.
Wind power, as you may have guessed by now, all weather on our planet is created by the
sun. Burning tree and cornhusks and other bio-mass, which we do in bio-mass powerplants,
all of those organisms originally got their power from our sun. And then, we have direct
solar power, which yes, gets its energy from the sun and skips all those middlemen. And
so it must be more efficient, right? Well, it turns out, it is more efficient, and you’d
think that being more efficient, it would be less expensive, unfortunately, it is not.
When we think about solar power, generally what we think of is photovoltaic cells, those
big blue panels that people put on their roofs to generate electricity. When I was researching
this, I was actually surprised to find we’ve known about the photoelectric effect for almost
200 years. It was discovered in 1839 by a 19 year old kid named Edmund Becquerel. Now,
I have to totally go on a tangent here because this is really interesting. Edmund Becquerel
is part of what we call a scientific dynasty. So Edmund Becquerel discovered the photoelectric
effect. His father discovered that you can refine ores into their pure metals using electrolysis,
and his son, along with Marie and Pierre Curie, discovered radioactivity. It’s just interesting
to me that there can be that much scientific talent generation from generation in one family.
It’s like Martin and Charlie Sheen, except with science and actually cool. Anyway, the
most efficient solar cells that we have tend to find their way into outer space, because
efficiency is expensive, but it doesn’t matter how expensive something is when you’re
dealing with the International Space Station, ‘cause it’s not like you can run a wire
up to it. The International Space Station has 16 115ft. long solar wings. All combined,
at peak, these solar panels produce 120 kilowatts of electricity, which, is a lot. And now I
can tell just by looking into your eyes that you’ve been filled with an insatiable desire
to know more about photovoltaic panels. So if you hit a wafer of polysilicon with light,
some of the electrons on that silicon will get knocked off and they’ll be free electrons.
Now, this is something that’s normal, but it’s not anything like the amount of power
that you would need to create a solar panel. But what scientists and engineers figured
out is that if you dope the silicon, and that’s a technical term, it just means lacing it
with impurities, if you dope the silicon with phosphorus, it suddenly has way too many electrons,
and then you get what we call N-type silicon, ‘N’ because it’s negative. And then
if you take another wafer of silicon, and you dope it with boron, that doesn’t have
enough electrons, and so you get P-type silicon, for ‘positive’. A traditional solar panel
is just a layer of N-type silicon sandwiched on top of a layer of P-type silicon, and then
connected with a conductor, which we call a wire. Stick something on top of that wire
and you can power it with a solar panel, and depending on the size of that panel, it could
be a calculator, a house, or a frickin’ space station. The trick is, how do we either
get solar panels to be so efficient that they can make up for their high costs, or find
new, less expensive materials, that we can use to create photovoltaic panels. Now I have
to get off topic a little bit here and talk about how solar power has an advantage that
not a lot of people think about. In general, when we produce power as humanity, we do it
at giant power stations that are often hundreds of miles away from where the power is actually
used. In order to get the power from the power station to your house, you have to put it
on these giant transmission lines, which are extremely expensive and also, having the power
travel all that distance is pretty inefficient. You can lose as much as 30% of the power that
you generate just getting it from one place to another, which, frankly, is embarrassing.
We created all those mega-tons of carbon dioxide just so we can lose the power when we’re
distributing it. And there’s a reason we do that, and that’s because with a coal-fired
power plant, you don’t want to have a bunch of little inefficient ones scattering the
landscape, you want to have one big one in one place where you can control the pollution
and make it as efficient as possible. But with solar power, you can actually generate
the power exactly where you’re using it. You can put the panel on your roof and use
it in your house. We call it ‘distributed power’, and it’s great. It does sometimes
make sense to use solar power in a centralized fashion, giant fields full of solar panels,
especially if those giant fields are in places where the sun shines 364 days a year. But
don’t get too excited, despite marvelous efficiency of distributed power, solar panels
still remain much more expensive than centralized power stations. Photovoltaic panels now blanket
rooftops all over the world, but while they make ecologic sense, they still don’t make
economic sense. Getting a good value for your dollar from a solar panel is pretty much impossible
which is why we’re still so reliant on coal and natural gas for most of our electricity.
To this day, we get more power from burning wood than we do from the solar panels. So
you’re saying to yourself, there’s got to be a better way to do this. And maybe there
is. If you were a particularly malevolent or scientifically-minded child, you may have
experimented with this technique in the past, using your magnifying glass to create power,
and you were probably using that power to kill small insects, which is not something
I condone, but there you have it. Sunlight carries a lot of energy, and if you concentrate
it into one place, you can do a lot of work and I prefer if we would be using that work
to push electrons into your house so you can watch me on your computer screen, not to use
it so you can vaporize small animals. Lenses like this are far too expensive to use in
solar power plants, so instead, we use mirrors. These are called concentrating solar power
plants, and in general, what’s done is we use the mirrors to focus light on a single
point, and there’s two real ways that it’s done. One, you build a giant tower, and then
you fill a field with mirrors, and you make sure that the mirrors are always focusing
the sun on the top of that tower. Now, as you might expect, building a giant tower that
can handle being heated to some ridiculous heat is kind of expensive, but it is cheaper
than pure photovoltaic. The other way that concentrated solar power works is that they’ll
build giant mirrored troughs, like parabolic sort of half-cylinders, and in the middle
of those, they’ll put a pipe, so by the time the oil is finished traveling through
this parabolic trough, it is so hot that as soon as it enters a vat of water, the water
immediately vaporizes, and that’s generally how powerplants work, you vaporize water and
the vapor takes up much more space than the liquid and so there’s a tremendous amount
of pressure and they use that pressure to drive a turbine, which creates electricity.
But even with all that fancy engineering, concentrated solar power plants still, in
the best of circumstances, only produce power at about 11 cents per kilowatt-hour, which
is about twice as much as a natural gas powerplant. But wait a minute, now we’ve got two solar
solutions. One, photovoltaics where the capture of the energy is the most expensive part,
and two, concentrated solar power, where the conversion of the energy into electricity
is the most expensive part. What if we could have both of these technologies, and have
the best of both worlds? Well, it turns out that we can, and it may just be the one solution
that allows solar power to become cost-effective in our energy market. By using really sophisticated
photovoltaic cells that can take in far more power than the one in your calculator, engineers
and scientists are using mirrors to concentrate light on very small photovoltaic cells. Now,
mirrors, which are actually capturing the light, are 10 times bigger than the solar
panel, and thus the solar panel is taking in 10 times more sunlight and producing 10
times more energy, but the solar panel itself, the expensive part, stays the same size. Using
this technique, which we call ‘concentrated photovoltaics’, we get the most cost-effective
form of solar power that we currently have on the market today. They call it ‘CPV’,
for ‘concentrated photovoltaics’, and there are several gigawatts of it getting
ready to go online in the next 10 years or so. It’s important to note that a gigawatt
is a lot of electricity, that’s about as much as produced by the largest nuclear powerplants
in America. Going back to the Space Station for a moment, mostly just because I want to
show more of the awesome graphics of the Space Station, as I said before, it doesn’t matter
how expensive the panels on the Space Station are, ‘cause there’s no other way to get
power up there. Now when I said that those solar panels create about 120 kilowatts of
electricity, I was kind of lying to you. About half the time, the panels on the Space Station
are producing 0 watts of power, and that’s because it’s in the shadow of the Earth.
And here on Earth, when we’re standing here, we call that shadow ‘night time’, and
it is the nemesis of solar power. And so unfortunately it would seem that solar power could never
satisfy 100% of our energy needs. We’ll always need something else, whether it’s
coal or nuclear or natural gas, to keep the lights on at night. Unless, of course, we
could find some way to store the power up during the day and then let it all loose at
night. Well, turns out, we kinda can. We can pump it up hills and then during the night,
let the water fall down through turbines generating electricity. Or we can pressurize giant closed
caverns in the Earth to thousands of PSI during the day, let the air escape to generate electricity.
We can heat salt until it melts, and then use the molten salt to boil water at night.
Or we can use the solar power during the day to split water into hydrogen and oxygen, and
then use the hydrogen in fuel cells to generate power at night. But unfortunately, solar power
is obviously already really expensive, and each one of these solutions to store that
power adds to the price. So while it’s feasible and we have created the solutions, implementing
them is just not in the near term. In physics, we have a thing called the Law of Conservation
of Energy, which says that you can’t get more out of a system than you put in. Well,
in economics, there might as well be a Law of Conservation of Dollars, which says that
people aren’t going to put more in than they have to in order to get a certain amount
of work done. Why would I climb over a mountain if someone’s already built a tunnel through
it? i mean, aside from the obvious fact that that tunnel releases hundreds of megatons
of carbon dioxide and other pollution into the atmosphere every single year. Meanwhile,
the biggest powerplants in America produce around 1,000 megawatts of electricity. If
we had 116 billion of those, it would be just enough to match the amount of power that the
sun shines down on our little planet every single day.
I’m Hank Green, solar power is awesome, and I hope you learned something.


    the new vestas wind towers are capable of producing enough electricity to power 50000 homes per tower.

    Does it sound like Hank's voice is quite a bit deeper than in more recent videos? I wonder what that's about.

    Well, instead of spending money on building nuclear submarines and aircraft carriers and spreading war and suffering to the world, I guess your government could invest some money in renewable energy generation and storage facilities… Greetings from Europe.

    you're not really good with units, it seems. Accounting for the angle under which the solar light strikes the surface in most desert regions, and the atmospheric mass it traverses, every square meter at sea level in the desert would get ca 1200+/-50 Watts of power, i.e. Joules per second. Considering that almost year round there is no cloud cover in the desert, and daytimes lengths only vary within 1-1.5h from 12h, it is safe to assume that every square meter would gather ca 0.7*12*365*1200*3600 Joules per year, a bit more than 13 GJ, or, your body with 1.5 m², around 20 GJ. Just to remind you: your daily metabolic balance is in the ballpark of 10 MJ, or 3 orders of magnitude lower. No wonder Superman is invulnerable, super strong and capable of unaided aviation, because he can absorb our "yellow sun's" radiation and output this energy even faster than he absorbs it in extreme circumstances. Back on topic: a photovoltaic power installation loses about a maginitude of power in absoption, transformation and transmission, and PV panels still yield a lot of nasty byproducts in production. A solarthermal installation on the other hand, while more expensive in construction, can get you 30 cents of brutto money output every year in electricity sales on every dollar you invest in the beginning, because it operates at an overall efficiency of around 25%, and all you need is steel, aluminum, oil and a reflective agent, and water to turn to steam to drive the turbines (which already give you AC, so you don't loose power in DC-AC transformation as you would with the panels). These Solar Thermal power plants also double as water desalinators, and the salt can be used to store excess heat which can be used to drive the turbines at night, reducing the need for batteries

    So if Hank's right, why is the middle east producing power from solar cells at 5c per kWh? That 5c factors in amortisation of infrastructure and neither coal nor nuclear can be that cheap when amortisation of infrastructure is included.

    Sо many uѕеful things tо uѕе this ѕоlаr air light [ Check Details here === ], I wоuld use it саmрing in thе middlе оf the night, I соuld аlѕо use it when thеrе is a lighting оutаgе, tо go dig thrоugh thе dark unitѕ in оur ѕtоrаgе, аmоng so mаnу оthеr imроrtаnt rеаѕоnѕ!

    Assistir ao Hank no inicio do Scy show é como assistir uma lagarta antes de entrar no casulo, todo comportado e bom rapaz…

    [Awesome Plan Here >>> ] It has just right information regarding solar electricity- its fundamental and how to size and install a system. Anyone with a little technical background can understand and follow easily. It illustrates real world solar electric design.

    How about an update considering that solar panels have reached parity with coal in desert regions and getting cheaper all the time.

    You also didn't mention the cost of disease, missed work, or early death from fossil fuels. This is nearly a TRILLION dollars in America alone. Seems rather important when discussing costs.

    Put the panel under the "solar torch", use silicone to waterproof it. Then cool the bottom of it with water.

    2018, although we're not as far removed from coal/natural gas and it's nice to see progress with the cost and efficiency of solar.

    I actually got a question wrong on an incorrect quiz, it said "which of these are an infinite resource" (or something along those lines) and I of course said coal, because coal is the dead corpses of living organisms, and since living organisms can reproduce and are infinite, so is coal. Stupid quiz.

    Thankfully, Solar power has advanced a good deal in the last 6 years. Somebody even figured out how to make the silicon sheets thinner not too long ago. Yay for making panels even cheaper! Not to mention that fossil fuels are finite, and will therefore continue to get more and more expensive.

    a microphone converts sound into electrical energy by magnetic induction and bees make noise in a hive 🐝 +🎤 = 🤔🤷‍♂️

    Hank!!! Great video bro! Can you update it with current breakthroughs and potential cost-saving technologies that have been introduced in the last 6 years? Awesome stuff.

    Instead of using a whole bunch of solar panels you could just use a 2 solar panels 1 to power a motor if you connected to a gearbox which is connected to a generator and an nother solar panel to charge a battery Bank for the night through a system just like Nikola Tesla made a system and not just one thing

    This should be revisited given the new changes in solar energy, from panels and paint that conduct energy from the sun and new tech in normal panels.

    Who is watching in 2018 and also if you go to Newport Elementary watch my vid I’m only asking people that go to my school in miss k Anderson…

    @ 8:39 – bullsh*t. 1GW is totally average for a nuclear plant. At least 60% of the nuclear plants in the US are rated over 1GW, with the largest well over 3 GW. I was waiting for this channel to show it's slight lefty side to this vid. Still, overall this vid was informative enough.

    "how can we make it cost less" Communism. There is no money under communism. does it cost money? no, what's money. lets make it anyway because its the smart thing to do

    I know this is a bit old but I would love to see your channel go over nuclear, it is a viable option that is not covered enough

    I'm pretty sure the Sun affects the tides also Hank. You guys even made a video about that very thing. So….only 1 energy source isn't originally solar powered. Correct me if I'm wrong.

    You uh, you know you can skip all those steps about pumping water up hills or electrolysis right? I mean there's this thing called a capacitor and it's purpose is literally to store electrical energy. I mean high quality capacitors can store huge amounts of charge for like a month.

    Hank explains this explanation is so detailed omg i love it! btw this video is also too great omg b

    One of the main reasons that solar power is 'expensive' is because solar energy is a substitute good with the products which compete with it. So, if we increase production of solar power, it reduces the demand, and therefore the short-term price, of other forms of energy, like natural gas, oil, etc.

    n and p type silicon are neutrally charged. The n and p refer to the charge of the free charge carriers within the material. In fact, if you put n next to p, free electrons from the n type will diffuse into the p type, making a small region of the n type positively charged and a small region of the p type negatively charged.

    Power is not energy. A wat is a Joule/s. 1500 Watts is worth 1.5 seconds of energy at Optimal sun conditions. The average power/m2 at peak sun is 1000W/m2.

    Wow, it is 4years later and solar has improved hugely and is affordable. I have 400 watts of monocrystalline panels feeding 800 amp hours of batteries on a van! I run computers cameras, a fridge, lights…love it.

    I'm here from the future! Solar panels are becoming cheaper and more efficient. South Australia uses a city sized battery attached to a windfarm that provides 110MW of power to the once blackout ridden state.

    In Canada the bulk of our energy bill is making heat, specially in winter. PV is not economical, on the other hand using solar thermal panels makes more sense. With the new high efficiency solar evacuated tubes on the market starting to drop in price, it starting to make sense. Seasonal heat storage is the next hurtle. Just like PV, the intermittent nature of solar means that storage technologies has to improve.

    Thanks for the Video clip! Apologies for the intrusion, I would love your initial thoughts. Have you heard the talk about – Schallingora Computer Reconstruction Scheme ( It is a good exclusive guide for saving money using this smart solar power trick without the hard work. Ive heard some decent things about it and my friend Sam after a lifetime of fighting got cool success with it.

    Please make an updated version of this video with less goatee and more updated numbers and PV technologies. 🙂

    White people laying out in the sun all day may absorb 1500 watts of solar energy, but they'd look like a piece of burnt toast.

    Outdated… you should update this video! 2019 everything changes… solar is the best energy source available!

    here it is 7 years later and its still cheaper to burn coal then to go complete solar,, still testing that theory … but its not the panels that cost the most… its the storage or batteries

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