How Solar Panels Work: From Scratch

First, let's look at the sun. This is a huge nuclear reactor 147.1 million kilometers away from us. It sends energy to the earth all the time. This energy is scattered into the universe in the form of "photons".

The photons reaching the Earth's surface every hour provide more electricity than we use all over the world in an entire year.

All this energy is completely free and you can use it yourself.

Harnessing that energy in a practical way - that's exactly what solar photovoltaic panels do

How do solar panels convert sunlight into electricity?

The solar panel is a collection of many solar cells (photovoltaic abbreviation PV) and covered with protective glass and fixed together with an aluminum alloy frame. These photovoltaic solar cells are made from the semiconductor material silicon, which is sliced ultrathinly.

Each photovoltaic cell has a negative electrode layer and a positive electrode layer. The negative electrode has extra electrons, and the positive electrode has holes to accommodate these electrons (you can imagine the state where the octopus balls have not been put into the pot). The electrons are moved by the built-in electric field, which creates a voltage difference, so with solar panels, we just need some energy to break the electrons out of their current binding, so they flow from the negative layer to the positive layer.

Yes, that energy source is the sun. The photons from the sun that hit Earth's surface all the time are the key to solving the problem of how solar panels work.

The energy from these photons frees the electrons in the negative pole of the photovoltaic cell from being bound by the magnetic field and makes them move, which means we now have a current that can flow, which is called the photovoltaic effect.

This is just the beginning of understanding how solar panels work, as these electrons need conductors to pass through and also act on electrical equipment. So how did this happen?

The paths we create for electrons are called circuits. As they leave the negative side of the cell, we want them to flow through our loads (like our LED lights and home appliances) so that the electrons can power those loads as they reach the positive layer of the cell.

The flow of current is important

Solar photovoltaic panels generate direct current (DC), but we use alternating current (AC) in our homes. To solve this problem, an inverter is added to our PV system to convert DC to AC.

Inverters are a key factor in how solar panels work because without inverters in our PV system, we can't do much with the electricity generated by solar panels.

The main types of inverters are centralized inverters, string inverters, and micro inverters.

Micro inverter

Microinverters are small devices that can be installed directly under solar panels. Microinverters are designed to process electricity from one (or sometimes two) solar panels, converting DC to AC on the spot. Some manufacturers even integrate microinverters into solar panels and call them "AC modules".

String Inverter

Larger string inverters are designed to convert the DC power of a large number of PV modules that make up a PV array. They range in size from as small as 3 kilowatts to as large as more than 200 kilowatts.

With these solar inverters, you can connect solar panels together in series and supply DC voltage to the inverter. The inverter then steps it down to an AC voltage suitable for the home or business where the system is installed.

Solar power starts with the sun. Solar panels (also known as "photovoltaic panels") are used to convert light from the sun (made up of energetic particles known as "photons") into electricity that can be used to power electrical loads. Solar panels can be used for a variety of purposes, including remote power systems for cottages, telecommunications equipment, remote sensing, lighting, and of course electricity production for residential and commercial solar power systems. But few people really understand how solar panels are made. What is the process?

Step 1: Sorting: Select the solar cells with different colors, serious color difference, dirty and missing corners, so as to avoid the appearance of defective products due to the problem of the cells during the final packaging. Eliminate the first step, and then perform EL test on the selected cells. 250 watt solar panel is to avoid problems that cannot be detected by the naked eye during the selection process, such as cell cracks, small gaps on the surface of the cell, but in the The use of solar panels in the later period will have a serious impact, and the life of the solar panels will be greatly reduced, especially at high temperatures, short circuits are prone to occur, causing fires, etc., so the potential hidden dangers should be eliminated from the beginning.

Step 2: Divide: Cut the selected cells, but design before cutting, and use every part of each cell as much as possible without causing waste. First of all, it must be based on customer requirements. To design the size of the solar panel for the power, the size of the solar cell is designed. Another thing to consider is the voltage of the solar panel, which will involve the number of solar cells required. The working voltage of each ordinary monocrystalline cell is 0.5V. If the customer needs a 18V solar panel, 18V/0.5V=36 small cells are required. After calculating the size, put the battery slices into the dicing machine, adjust the machine, and cut in batches. After cutting, break the pieces. After breaking, place them according to the positive and negative poles of the battery.

The third step: string welding: Now basically all are machine automatic string welding, unless it is a large, relatively special process. Put the battery box of the finished battery slices on the string welding machine, put the copper tapes together, and adjust the machine to a suitable temperature. Pay special attention to the positive and negative poles of the battery slices. Do not put them in reverse.

Step 4: Lamination: Test the welded cells. After passing the test, the cut PET and EVA are laminated in sequence. First, the surface material is PET, and then EVA. EVA is at room temperature. It is a solid state, and it becomes a liquid state at high temperature. EVA plays the role of an adhesive here, bonding the surface material, the battery sheet, and the back material together, and then the battery is welded together. Sheet, then a layer of EVA, and then the backplane epoxy board.

Step 5: Lamination: Put the stacked solar panels into the laminator, remember to cover the surface with a high-temperature cloth, and adjust the temperature of the machine and the lamination time to avoid lamination, use Later at high temperature, delamination is caused.

Step 6: Edge trimming: Manually trim the excess EVA glue, and finally perform a simple cleaning.