At Renogy, we are proud to manufacture some of the toughest equipment in the industry. Let’s check out what solar panels are made of and the two most common types of panels that we offer.
If you are interested in what improvements are made on solar panels in recent years, you may want to read How Solar Panels And Solar Energy Have Evolved Over The Past 5 Years.
What makes up a solar cell?
There are many components in a solar panel. One of the most critical elements is the solar cell. When sunlight hits the cells, they use the photovoltaic (PV) effect to convert sunlight into electricity.
The two most common types of solar cells are monocrystalline and polycrystalline, which utilize silicon as their base material.
Here’s a high-level look into how our solar cells are created:
Polycrystalline solar cells
1.We begin by taking quartzite ore that was mined from the earth. We process the ore through several steps to extract metallurgical silicon. The rest of the tech industry uses the same method to refine silicon for various components.
2.We refine the metallurgical silicon until it's 99.99999% pure. We only use a pure silicon base material. Otherwise, the efficiency and durability of our solar cells would suffer.
3.The silicon is melted down and poured into molds to form a large block called an ingot.
4.This ingot is sliced into thin wafers.
5.The wafers undergo a process to improve their surfaces for catching sunlight.
6.The wafers are coated with a phosphorus-based substance that helps facilitate the formation of "p-n junctions." These junctions are important for converting light into electricity.
7.An Anti-reflective coating is applied to the wafers since they need to capture the sunlight, not reflect it.
8.Finally, our new solar cells are ready for assembly.
*This is an extremely high-level overview of the process. The actual method involves precision, experience, and the right tools to do it properly and safely. Do not attempt this yourself.
Monocrystalline solar cells and polycrystalline solar cells are produced similarly, except for the third step of monocrystalline cell production, during which various methods can be employed to produce the actual monocrystalline ingots.
The most commonly used method is the Czochralski method, also known as the "CZ method." A rod with a silicon "seed" crystal on its end is dipped into the molten silicon. The seed reacts with the molten silicon and forms a new crystal. The rod is then slowly pulled out of the mixture under rotation, thus "growing" or pulling a pure monocrystalline ingot from it. If you chocolate-covered candy or dipped candles when you were younger, this process will be familiar to you.
The CZ method is chosen because it provides a superior product while still allowing control of the ingot being created. A dialed-in factory can control the size, purity, occlusions, and more of the ingot.
Some of the other methods, like zone melting, can grow seed crystal ingots on a polycrystalline rod when heated by a radiofrequency heating coil. The Bridgman technique involves passing the crucible containing the molten silicon and seed from a hot zone to a cold one. During the process, the seed will grow.
Panels with Monocrystalline solar cells are typically more expensive due to the greater precision that it takes to make them. However, the tradeoff is that you get a panel with much greater efficiency. That greater efficiency means these panels can be significantly smaller and generate the same number of watts.
Image source: sciencedirect
Image source: sciencedirect
Solar panels: what is a solar panel, and How are solar panels made?
A solar panel is a device that captures sunlight and turns it into usable energy.
As we covered above, you've seen that solar cells are made from silicon, etchings, and coatings. Now, what about the rest of the panel?
Let's take a look at that.
Solar Panel Components
A solar panel comprises solar cells that are welded together, TPT films, EVA films, glass, frames, and more.
Step #1: Solar cell testing
We conduct a quality test to divide our solar cells into A, B, or C grades. Only the best ones receive the coveted A rating. Cells that are graded higher are more efficient and will keep producing power for longer than their lower-grade siblings. Generally, this is a key difference between lower-cost solar panels and more expensive ones.
Cells with damaged grids, thin printing, or imbalanced coatings will receive a B-rating. Recycled cells with significant defects, like extensive weak printing, and loose grids, will receive a low C-rating.
A photovoltaic cell I-V test system can quickly tell to which group these solar cells belong.
Step #2: Single and series solar cell welding
During this stage, the solar cells are welded together so they'll stay put inside the solar panel's frame and help ensure proper conductivity among cells. Remember that solar cells are quite delicate, meaning any bumps or weak welding junctions caused by human hands can damage them. So, it's important that this process is finished with machines.
Step #3: Overlapping the layers
Solar panels are giant sandwiches from different layers stacked together. The layers, TPT film, EVA film, now-welded solar cells, EVA film, and glass panels are individually placed to make a composite.
Now, the panel undergoes an Electroluminescence (EL) test. The EL test is a non-invasive procedure that can be repeated every so often after the solar panels are installed. The test looks for microcracks in the cells and other layers. Even the most minor fissures can harm performance.
Step #4: Machine laminating
Once our panels pass the EL test, the stacked components head to a special machine for lamination. Using a vacuum, we create a negative pressure environment that removes any air that is between the layers to ensure there are no bubbles. The outer EVA film is heated to its melting point, bonding the sandwiched layers together.
Step #5: Frame and junction box mounting
For the panel types that get a frame, this is the step. After this, the solar panel is complete.
Step #6: Product test and packaging
This is a step that separates us even more from the competition. Each panel is thoroughly and painstakingly tested and inspected. Every aspect is judged to ensure it's up to our quality and performance standards. Even though it costs a little bit more to handle products this way, it is worth it in the end to deliver the best solar panels that we can and ensure they will last for many years to come.
Now that you’ve known how monocrystalline and polycrystalline solar panels are made, you might want to know more about their differences, which can be learned in What’s The Difference Between Monocrystalline And Polycrystalline Panels?
What’s the percentage of panels made in the US?
This probably won't surprise many people, but only about 20% of solar panels are made in the US. Only 5% of the materials and components used in producing US-made panels are from the United States. That means nearly 80% of panels and 95% of components are created in China.
Only The Best
At Renogy, our passion is solar energy. We take great pride in the products we design and sell. We offer the highest-quality monocrystalline solar panels on the residential market. You simply cannot beat our best-in-class warranty. Through our commitment to unleashing the solar industry’s potential, we strive to deliver the best products and customer service we can. Check out our 12 Volt battery offerings, lithium RV batteries as well as solar powered generators today!