parties to the United Nations

聯合國締約國

Framework Convention on Climate Change

氣候變化框架公約

reached a landmark agreement.

達成了一項具有里程碑意義的協議。

One hundred and ninety-five nations,

一百九十五個國家。

practically every country in the world,

世界上幾乎每個國家都有。

were going to officially fight against the climate crisis.

要正式對抗氣候危機。

This is now known as the Paris Agreement.

這就是現在所說的《巴黎協定》。

And the main goal of that treaty

而該條約的主要目標是

is to limit global temperature rise

是限制全球氣溫上升

to well below two degrees Celsius.

到遠低於兩攝氏度。

But in order to save the Earth from rising temperatures,

但為了拯救地球，防止氣溫上升。

we need to remove billions of metric tons of carbon

我們需要清除數十億噸的碳。

from our atmosphere every year.

每年從我們的大氣層中。

To help accomplish this,

為了幫助實現這一目標。

countries have been investing in negative emissions

國家一直在投資於負排放

and low-carbon technologies,

和低碳技術。

as well as adding infrastructure to support them.

以及增加基礎設施來支持它們。

And solar energy is already at the forefront

而太陽能已經走在了前列

of this renewable revolution.

這場可再生革命的。

Why? Because the sun is the most abundant

為什麼呢？因為太陽是最豐富的

energy resource we have on our planet.

我們地球上的能源資源。

But how much do you know about solar panels

但你對太陽能電池板瞭解多少

and how exactly do they work?

他們到底是如何工作的？

Well, let's start with photovoltaic cells.

好吧，我們先從光伏電池說起。

These cells are what convert sunlight into electricity.

這些電池是將太陽光轉化為電能的。

A single photovoltaic cell, also called a solar cell,

單個光伏電池，也叫太陽能電池。

can be smaller than a postage stamp

小於郵票

and thinner than a human hair.

而且比人的頭髮還細。

On its own, a solar cell can generate about half a volt.

單獨一個太陽能電池可以產生大約半伏的電壓。

So, to increase this energy output,

所以，為了增加這種能量輸出。

you can combine these solar cells

你可以把這些太陽能電池結合起來

to create solar modules

以製造太陽能模塊

and even slightly-bigger solar panels.

甚至稍大的太陽能電池板。

Depending on their size

根據其大小

and the materials they're made of,

以及它們的材質。

as well as the amount of sunlight that's available,

以及可用的陽光量。

the power output of solar panels can vary.

太陽能電池板的輸出功率可以變化。

This output, or the amount of energy a panel produces,

這個輸出，也就是一個面板產生的能量。

is measured in kilowatt-hours.

以千瓦時為組織、部門。

So, if a panel generates 100 watts in one hour,

所以，如果一塊麵板在一小時內產生100瓦的功率。

that would be 100 watt-hours or 0.1 kilowatt-hours.

這將是100瓦時或0.1千瓦時。

But you can combine modules and panels even further

但您可以進一步結合模塊和麵板

to create solar arrays.

以創建太陽能電池陣列。

These structures are what are used to power homes

這些結構是用來為家庭供電的

and even spacecraft.

甚至航天器。

And if you gather enough solar arrays in one place,

而如果你在一個地方聚集了足夠多的太陽能電池陣列。

you can even power cities.

你甚至可以給城市供電。

You may have seen swaths of land

你可能已經看到了大片的土地

covered in solar arrays.

覆蓋在太陽能陣列上。

These are often called solar farms or solar parks.

這些通常被稱為太陽能農場或太陽能公園。

The largest solar park built to date

迄今建成的最大太陽能園區

is the Pavagada Solar Park in India.

是印度的帕瓦加達太陽能公園。

It spans over 53 square kilometers

佔地53平方公里

and can produce two gigawatts of electricity,

並能產生兩千兆瓦的電力。

which is enough to power 700,000 households.

這足以為70萬戶家庭供電。

By the end of 2018,

到2018年底。

the world's installed capacity of solar cells

世界太陽能電池的裝機容量

reached over 480 gigawatts,

達到480多吉瓦。

representing the second largest

第二大

renewable electricity source after wind.

風力之後的可再生電力來源。

Now, this may seem like a lot of energy already,

現在，這可能看起來已經是一個很大的能量。

but researchers are projecting that by 2050

但研究人員預計，到2050年

the world's solar cell capacity

世界太陽能電池產能

could reach over 8,500 gigawatts.

可以達到8500吉瓦以上。

This is the kind of expansion we need

這就是我們需要的擴張

to reach the carbon-cutting goals

實現減碳目標

of the Paris Agreement.

《巴黎協定》。

The big reason why photovoltaic cells

光伏電池的重要原因是

haven't taken over the world yet

尚未稱霸世界

is because the technology is still limited

是因為技術還很有限

by three important factors.

由三個重要因素決定：

Cost, efficiency and reliability.

成本、效率和可靠性；

Efficiency basically just means

效率基本上只是指

how well a solar panel is able

太陽能電池板的性能如何

to convert sunlight into electricity,

將太陽光轉化為電能。

and cost can be defined by, well,

和成本可以通過，來定義。

how much goes into making a solar cell

製造一個太陽能電池需要多少錢

like materials, manufacturing,

像材料、製造。

distribution, installation,

分配、安裝。

relative to how much wattage is generated

相對於產生多少瓦數

in return for that investment.

以此作為投資的回報。

And lastly, we have to make sure a solar cell

最後，我們必須確保太陽能電池

can generate power on sunny and cloudy days,

可在晴天和陰天發電。

which is tougher than you might think.

這比你想象的要難。

In recent years, advances to solar energy technology

近年來，太陽能技術的進步。

have helped it become more accessible

幫助它變得更加方便

to the average person like you and me,

對你我這樣的普通人來說。

and to the teams taking part in the World Solar Challenge.

和參加世界太陽能挑戰賽的隊伍。

So, basically, the sun provides energy

所以，基本上，太陽提供能量

in the form of photons.

以光子的形式。

And when those photons will hit your solar ray

當這些光子擊中你的太陽光時

when it hits your solar cells,

當它擊中你的太陽能電池時。

the photons excite electrons

光子激發電子

and those will jump across the band gap

而這些都會跳過帶隙

inside your solar cell

在您的太陽能電池內

and they'll basically flow through your circuit.

他們基本上會流經你的電路。

So, you get this flow of electrons.

所以，你會得到這種電子流。

Today, the most popular semiconducting material

今天，最流行的半導體材料

used in solar cells is silicon.

太陽能電池中使用的是硅。

Diving in even deeper,

潛入得更深。

we'll see that crystalline silicon cells

我們將看到，晶體硅電池

are made of silicon atoms connected to one another

是由硅原子相互連接而成的。

to form a crystal lattice.

以形成晶格。

Silicon bonds are made of electrons,

硅鍵是由電子構成的。

the negatively-charged particles in an atom.

原子中帶負電的粒子。

These electrons allow it to perfectly bond

這些電子使它能夠完美地結合

to its silicon neighbors,

到其硅鄰居。

creating this perfectly organized

渾然天成

lattice structure.

格結構。

In a solar cell,

在太陽能電池中。

there are two layers of silicon.

有兩層硅。

One layer, n-type, has a negative charge,

一層，n型，帶負電荷。

and the other layer, p-type, has a positive charge.

而另一層p型則帶正電荷。

Now, each charge needs to be enhanced

現在，每項收費都需要加強

to create the energy we're looking for.

來創造我們所要的能量。

And to do that, researchers will dope

為了做到這一點，研究人員將摻入

or add other elements to the silicon material,

或在硅材料中加入其他元素。

giving it extra electrons,

給它額外的電子。

or creating empty holes for electrons to fill.

或製造空洞讓電子填充。

The negative charge is usually achieved

負電荷通常是這樣實現的

by mixing the layer of silicon with phosphorus.

由硅層與磷層混合而成。

This adds extra electrons to the mix,

這就增加了額外的電子。

allowing more electrons

允許更多的電子

to roam freely in the lattice.

在格子中自由遊走。

A positive charge for that p-layer

該p層為正電荷

is achieved by doping that layer with boron,

是通過在該層中摻入硼來實現的。

causing those spaces called holes.

導致這些空間被稱為孔。

The boundary between the two layers

兩層之間的邊界

is called the p-n junction,

被稱為p-n結。

while the area around it

而周邊地區

is known as the depletion region.

被稱為枯竭區。

So, now for the fun part.

所以，現在是有趣的部分。

When light from the sun hits those layers,

當太陽光照射到這些層次的時候。

the energy from the photons knocks electrons loose.

光子的能量使電子鬆動。

Because the layers are oppositely charged,

因為各層都是帶對立電荷的。

the electrons want to travel

電子要走

from the n-type layer to the p-type layer

從n型層到p型層

to fill its empty holes.

以填補其空洞。

The electrons create a voltage difference

電子產生電壓差

between either end of the cell.

在細胞的兩端之間。

So, by adding an electric circuit to one end,

所以，通過在一端加一個電路。

the electrons can travel through that circuit,

電子可以通過該電路。

powering devices along their way

為沿途的設備供電

and end up in the p-type layer.

並最終進入p型層。

[EXHALES] Okay, we did it.

[呼氣] 好吧，我們做到了。

We made it through the molecular explanation

我們通過分子的解釋

of how solar cells convert sunlight into electricity.

太陽能電池是如何將太陽光轉化為電能的。

But typical crystalline silicon PV cells

但典型的晶體硅光伏電池

only convert 18 to 22% of sunlight

只將18%的陽光轉化為22%的陽光

into electricity.

成電。

And that's clearly not enough.

而這顯然是不夠的。

We want solar cells to be as efficient as possible

我們希望太陽能電池的效率儘可能高。

so they can power as many things as possible.

所以他們可以為儘可能多的東西供電。

And the teams competing in the World Solar Challenge

還有參加世界太陽能挑戰賽的隊伍

are already using an advanced material to do so.

已經在使用一種先進的材料來做。

The typical material to make solar cells out of is silicon,

用硅做太陽能電池的典型材料是硅。

and this is a car covered in silicon panels.

而這是一輛被硅板覆蓋的汽車。

They're allowed up to four square meters.

他們被允許在四平方米以內。

But recently a lot of cars air switching over

但最近很多車都換氣了

to a different material, gallium-arsenide cells,

到不同的材料，砷化鎵電池。

and they're significantly more efficient.

而且它們的效率明顯更高。

Gallium-arsenide is a semi-conducting material

砷化鎵是一種半導電材料。

made from the elements gallium and arsenic.

由鎵和砷元素製成。

Gallium-arsenide solar cells

砷化鎵太陽能電池

now hold the world efficiency record

現在擁有世界效率記錄

for a single junction solar cell,

為單結太陽能電池。

with a conversion rate of just around 28.8%.

與轉化率僅為28.8%左右。

So what's stopping us from using that in everything?

那麼，是什麼阻止了我們在所有的事情上使用它呢？

Well, making a wafer of gallium-arsenide

好吧，做一個砷化鎵的晶片

is considerably more expensive than making a silicon wafer.

比製作硅片要貴得多。

The size of the gallium-arsenide array

鎵-砷化物陣列的大小。

was 3.56 square meters,

是3.56平方米。

and to cover that size array, you need about 100 grand,

而要覆蓋這個規模的陣列，你需要大約10萬。

um, to cover the same amount of area,

嗯，以覆蓋相同的面積。

actually to cover about four square meters.

實際上要覆蓋四平方米左右。

So even a larger area of silicon,

所以即使是更大面積的硅。

you'll need about 3 grand,

你需要大約3千塊錢。

so there's a huge price difference.

所以有一個巨大的價格差異。

So researchers are still trying to find that perfect solar cell

所以研究人員仍在努力尋找那種完美的太陽能電池。

that is both cost effective and full efficiency.

是既省錢又能充分發揮效率的。

Innovations like those used in the World Solar Challenge

諸如世界太陽能挑戰賽中所使用的創新技術。

are going to continue to push the boundaries

將會繼續推陳出新

of renewable solar technology.

的可再生太陽能技術。

And now that you have a solid grasp

現在，你已經有了一個堅實的把握

on how solar panels and photovoltaics work,

關於太陽能電池板和光伏的工作原理。

let's take a closer look at how we can apply

讓我們來仔細看看我們如何應用

all of this solar tech to a race car.

所有這些太陽能技術的賽車。