Quartz Sandy In Solar Cell

Improving the productivity of solar modules, inverters, and heat pumps will require building more and larger factories around the world (not just in China) to not only assemble these modules, but also to produce the parts and components needed to make them. This is the more complex of the two problems and will require time, expertise, investment, and most likely a lot of government support to build (or rebuild) domestic manufacturing capacity for the various products needed.

To give you a more concrete understanding of this, here is a brief overview of what it takes to make a solar panel.

What is a solar module?

First, it's helpful to understand what a solar module is, especially because the terminology can be a little confusing (for example, a solar panel can refer to a single solar module or a row of solar modules connected together).

So let's be clear here about how we use terminology. The way we use the terminology here is that a solar module refers to a group of solar cells arranged as a unit and held together by a frame (in other words, you could call it a single solar panel). But we'll reserve the term solar panel to refer to a row of solar modules connected together.

A solar array is a group of solar panels connected together (literally, rows of solar modules). Finally, a photovoltaic system consists of an array of solar cells, along with solar inverters, batteries, and more, which are necessary for a small solar power plant to fully operate.

So, solar modules. We've all seen them on rooftops, but what exactly are they?

Although thin and flat, solar modules are made up of multiple parts. The solar cells in a solar module are arranged in a flat layer, giving the solar module a grid-like appearance, and convert sunlight into electricity by shunting electrons (which are negatively charged) to create a charge difference between one location and another, which generates electricity.

This layer of solar cells is sandwiched between top and bottom clear plastic films, which hold all the solar cells in place. This layer of solar cells is sandwiched between two sheets of clear glass for protection and waterproofing.

In most types of solar modules, there is a durable plastic sheet underneath the bottom glass. This plastic sheet can be black (for aesthetics), white (to increase the solar module's efficiency in using sunlight by reflecting some of the uncollected sunlight back to the solar cells to generate more electricity), or clear (to allow light to pass through, for example, if you are using the solar module as a sunshade but don't want to block too much light).

The assembly is fixed inside an aluminum frame, and a junction box with diodes and electrical connectors is placed at the base of the solar module, and it’s ready to be mounted on your roof!

There’s nothing special about the glass, plastic, aluminum, and wire components of a solar module.

Their manufacturing may not be what’s holding us back from an exciting, clean, new, renewable world where cars quietly zip by, emit no pollutants and greenhouse gases, and everyone’s home is almost completely self-sufficient. However, our ability to manufacture solar cells and assemble them into solar modules is another story.

We absolutely need to build more factories to produce solar cells and assemble them into modules, or we really will be decades away from fully achieving renewable energy generation. Imagine all the walls, rooftops, and fields suitable for agricultural solar energy in the world waiting for photovoltaic systems, and there are only a few factories currently located, mainly in China.

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The manufacturing process of solar cells

At the end of the day, every solar cell begins with quartz sand. Also known as silica sand, quartz sand is composed of at least 95% pure silicon dioxide (also known as silica or SiO 2 ).

But solar cells don't need silicon dioxide, they need silicon, which means we need to remove the oxygen, leaving behind pure silicon. The silicon in silicon dioxide doesn't like to be separated from oxygen, so this requires powerful chemical techniques.

Industrially, this requires liquefying sand in a furnace at 2000°C (3630°F) while burning high-carbon coals such as coke to release carbon atoms. These carbon atoms need oxygen more than silicon, so they steal the oxygen and combine it with themselves to form carbon dioxide (CO 2 ). This leaves behind a fairly pure silicon melt, which is collected and cooled into small pieces of blue-grey silver.

The next big feat is to turn the polysilicon into a huge, beautiful crystal, then carve it into ingots, which are then cut into solar cell-sized wafers. If you want to get wafers large enough to make solar cells, there are several ways to do this. The most practical method currently is the Czochralski process, which involves placing a single spinning silicon crystal into a silicon melt that is spinning in the other direction, and then slowly pulling it out (a few millimeters per hour).

This results in the growth of cylindrical silicon crystals that can weigh hundreds of kilograms, be up to 450 millimeters in diameter, and be up to two meters long. If you're wondering how intense this process is, the melting point of pure silicon is around 1400°C (2550°F).

As far as materials go, pure silicon is very hard. This means you need to get out your (very clean) diamond wire saw and cut the cylindrical silicon crystals into ingots with the volume of a solar cell. Then, because this silicon crystal is also very brittle, you have to get out a very long diamond-studded wire, also very clean, and string it together so that you can cut all the (usually) 160 millimeter-thick silicon wafers out of the up to two-meter-long single crystal silicon ingot at the same time.

Next, the single crystal silicon wafers go through a series of acid baths and water rinses, then are gently polished and dried. After that, both sides of the wafer are coated with a thin film of amorphous silicon that has been doped with trace elements such as phosphorus, arsenic, boron, or aluminum, which can act as electron donors or electron acceptors, allowing the solar cell to generate electricity from sunlight.

Thin silver wires, called busbars, and even thinner metal wires, called finger wires, are then applied to the surface of the wafer to serve as electrical contacts. At this point, at least for now, the cells are cut in half, as this improves efficiency.

How Solar Modules Are Made

The next step in solar module production is to connect the half-cells into strips, which are then used in rows to build modules.

Almost all of the work that converts the wafers into strips of solar half-cells is done on extremely complex automated assembly lines that can easily be close to a kilometer in length from start to finish.

People still need to perform quality control on the cells at various stages of cell production and monitor the machines, which are smart because they have a ton of sensors guiding them, but also dumb because that doesn't mean they can think carefully or solve problems when something goes wrong (they often do, as anyone who has ever dealt with a system with a ton of complex but finicky sensors will be happy to tell you).

You would probably need to run a factory that produces enough solar cells to produce enough solar modules per year to generate 1 gigawatt of electricity, which would require about 140 employees working in shifts (because these assembly lines run 24 hours a day for years, and because even if you shut them down briefly, it takes at least a week to get them running smoothly again).

From now on, all you have to do is put all the components (half-cell strips, plastic sheets, glass panels, thick and durable plastic film backsheets, aluminum frames, junction boxes and wires) together to form a working solar module.

This would probably require an entire large factory floor with nearly a kilometer of assembly lines and workers monitoring quality control, as well as an easily confusing array of robotic arms, furnaces, plasma torches, conveyor belts and guns that shoot flat plastic strips that wrap a bundle of solar modules together, which can then be securely wrapped in plastic film, boxed and shipped to the installation site.