Generate Electricity – How Solar Panels Work!

Sure! Here’s a sanitized version of the YouTube transcript, with unnecessary repetitions and informal language removed for clarity:

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**Transcript:**

Why are there crystals here but not on this one? How do solar panels work? Let’s find out.

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Solar panels convert light into electricity. They are photovoltaic, meaning they generate voltage from light. This works with sunlight or artificial light.

To demonstrate, take a small solar cell, set up a multimeter, connect the leads, and expose it to light. We instantly see that a voltage is generated; the stronger the light, the more electricity is produced.

If we connect the solar cell to a power supply, it produces infrared light. The human eye can’t see this, but if we take a camera and remove the filter, we can see that light is being produced from the cell.

Light consists of particles called photons. The solar cell absorbs these photons, which knock electrons out of the solar cell, leaving holes behind. This is known as the photovoltaic effect. The hole drifts down to the bottom, and the electron is pulled into the top layer. The electron is attracted to the hole, similar to how opposite ends of a magnet attract.

If we provide a path using a wire, the electron will flow through it to get back to the hole. We can place devices such as LEDs in this path, causing them to emit light, which means they emit photons.

If the LED emits photons and the solar cell absorbs photons, can the LED power itself? Let me know your thoughts in the comments, and I’ll reveal the answer later in the video.

You may have seen solar cells in calculators or garden lights. They are often used in motor homes, boats, and on houses, as well as in large solar arrays in fields. An array consists of multiple strings of solar modules connected together.

A solar module is made up of multiple solar cells. It starts with a metal conductive plate that forms the positive electrode. On top of this, there is a thin silicon layer, which serves as the semiconductor material. Typically, this consists of a layer of silicon-boron mixture on the bottom and a layer of silicon-phosphorus on top, known as the PN junction.

An anti-reflective coating is applied on top of the silicon, and a metal grid is placed over this, which serves as the negative electrode. The thin strips are known as fingers, and the thicker strip is called the bus bar. A glass protective layer is typically placed over this to prevent damage, as solar cells are thin and fragile.

Each solar cell generates about 0.5 volts. To create a solar module, we have a solid back sheet with a layer of EVA adhesive, onto which the solar cells are attached and connected. Another layer of EVA film sits on top, followed by a layer of glass, and finally, a frame is fitted on the back. The EVA encapsulates the solar cells, insulating them from moisture and mechanical stresses.

Looking at the solar modules, the top of one cell connects to the bottom of the next, increasing the voltage. Small modules typically use 36 cells, producing around 18 to 19.8 volts, which is suitable for charging a 12-volt battery. Most residential installations are grid-connected and use 60 or 72 cell modules.

When we connect cells in series, the voltage adds together while the current remains the same. For example, a module with 60 cells, each providing around 0.5 volts and 8 amps of current, produces around 30 volts and 8 amps, giving us 240 watts of power.

If we connect four of these modules in series, we would get 120 volts and 8 amps, totaling 960 watts. If we connect four in parallel, we get 30 volts and 32 amps, which also gives us 960 watts. We often use a combination of series and parallel connections.

The modules connect to a charge controller and inverter, which have maximum and minimum voltage and current requirements. For example, one might operate between 100 to 150 volts and 25 amps.

A solar panel can directly power a load when exposed to light. For instance, a solar fan will automatically turn on in bright light but will not work at night. Therefore, we need a battery to store energy, which charges during the day for use at night.

However, the voltage and current can vary, and the solar module can overcharge the battery, which can damage it. At night, the battery can discharge back through the solar panel, so we use a charge controller to separate them.

When the sun shines, the controller charges the battery, and we can switch the light on, with any excess energy going to charge the battery. At night, the controller protects the solar panel from the battery while allowing us to use the stored energy.

This is how solar-powered phone chargers work. In a simple garden light, we have just a solar cell connected to a basic charge controller, which separates the battery and the LED. The solar cell charges the battery, and when charging stops, the light is powered.

The solar panel and battery provide DC electricity. If we connect a multimeter to a battery, we see a constant flatline voltage, as electrons flow in one direction. This can power small DC motors, lights, and USB devices, making it suitable for motor homes and boats.

However, many appliances require AC electricity, which flows in alternating directions. To power these devices, we need an inverter, which converts DC into AC. Inside the inverter, electronic switches turn on and off rapidly to control the path of the electrons.

For domestic and commercial installations, we often connect to the electrical grid. In a simple system, we have just the solar panels connected to an inverter, which feeds the breaker panel and AC loads in the property. The electrical grid connects via a meter to the panel, and the inverter must synchronize with the grid.

At night, no solar energy is generated, so we buy electricity from the grid. On sunny days, the solar panels may provide enough energy to power some items in the home, and excess energy can be sold back to the grid through net metering.

More advanced systems use a battery bank, requiring a charge controller. The solar modules charge the batteries and power appliances, and when the batteries are full, excess power is sold back to the grid. At night, the batteries power the home until empty, at which point electricity must be purchased from the grid.

In the event of a power cut, the batteries will power the home until they are empty, and then they will recharge during the day. Solar farms have multiple rows of solar panels generating higher voltages, which combine and connect into a large inverter before being fed into a transformer substation.

The challenge with solar energy is that the sun moves from east to west daily, and its position changes with the seasons. Solar panels work best when perpendicular to the sun.

To optimize solar panel placement, we assess the location for the altitude and azimuth of the sun at that latitude, check for shading, and choose the best orientation and tilt angle for the module. This involves data analysis and calculations, which can be time-consuming.

With PV case, our sponsor, you can simulate the actual location using advanced software that incorporates 3D topographical data points. This allows for prototyping designs, assessing electrical cabling routes, and optimizing module placement.

You might have noticed that solar cells come in different types: crystalline and thin-film. One common type is the polycrystalline cell, which typically has blue flakes. These flakes are individual silicon crystals, and while they look beautiful, the boundaries reduce the efficiency of the cell.

Polycrystalline cells are relatively cheap but have an efficiency of around 13 to 17%. They are made by melting silica sand and carbon in an electric arc furnace, forming large chunks of raw silicon.

Monocrystalline cells are more efficient, around 15 to 19%, but are more expensive to produce. They are made from pure silicon, which is melted and cooled to form a single crystal structure.

Thin-film types, such as amorphous silicon, are flexible and often used for curved roofs or portable applications. They are cheaper to produce but less efficient, typically around 5 to 8%.

When discussing efficiency, we refer to how much solar energy is converted into electricity. The energy travels in waves, with different sizes ranging from high-energy gamma rays to low-energy radio waves. Most emitted energy is in the ultraviolet, visible, and infrared regions.

The visible spectrum is what the human eye can see. The wavelength determines the color of light perceived. In solar cells, photons must knock electrons free from silicon atoms to generate electricity. Silicon is chosen because it requires around 1.1 electron volts to free an electron.

However, excess energy can be wasted as heat, and efficiency decreases as solar cells heat up. Additionally, energy losses occur in the inverter and wiring.

In summary, a solar cell operates by generating DC electricity when light hits it, creating a flow of electrons. This is how solar energy is harnessed for various applications.

Check out these videos to learn more about engineering, and I’ll catch you in the next lesson. Don’t forget to follow us on social media and visit the engineering mindset website.

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