Science Energy What Are Solar Panels Made Of? Understanding solar panel materials can help you make an informed purchasing decision. By David M. Kuchta David M. Kuchta Writer Wesleyan University, University of California, Berkeley David Kuchta, Ph.D. has 10 years of experience in gardening and has read widely in environmental history and the energy transition. An environmental activist since the 1970s, he is also a historian, author, gardener, and educator. Learn about our editorial process Updated July 6, 2022 Fact checked by Elizabeth MacLennan Fact checked by Elizabeth MacLennan University of Tennessee Elizabeth MacLennan is a fact checker and expert on climate change. Learn about our fact checking process Share Twitter Pinterest Email Treehugger / Alex Dos Diaz Energy Renewable Energy Fossil Fuels In This Article Expand Parts of a Solar Panel Inverters Silicon Solar Cells Newer Solar Cell Technologies Solar Panel Manufacturing Frequently Asked Questions If you are purchasing solar panels for your home, you may be wondering how soon the panels will pay for themselves. Knowing what solar panels are made of can actually help you answer this question. Solar panel materials factor into how much the panels cost and how much energy they can produce. That, in turn, factors into how efficient the panels are at converting sunlight into electricity. This article will help you understand what solar panels are made of and how the cost and payback time of any solar investment depends on your choice of solar panel. Parts of a Solar Panel Solar panels are made of many different components: An aluminum frameA glass coverTwo encapsulants providing weather protectionPhotovoltaic (PV) cellsA backsheet to provide more protectionA junction box connecting the panel to an electric circuitAdhesives and sealants between the partsInverters (only in certain cases) The key components to pay attention to are the inverters and the photovoltaic cells. Differences in these parts have the greatest effect on the efficiency and cost of your solar investment. Inverters An inverter converts the direct current (DC) electricity that solar panels generate into the alternating current (AC) that homes and the electric grid run on. Inverters come in two forms: string inverters and micro-inverters. String inverters are the more traditional type of inverter and are sold separately from solar panels themselves. A string inverter is a stand-alone box of circuitry that is installed between the array of solar panels and the house's electrical panel. It is less costly but potentially less efficient than a micro-inverter. Just as an entire string of Christmas lights, wired in a series, can go out if one of the bulbs goes out, a string inverter is affected by the output of the weakest solar panel in the array. Some solar panel manufacturers build micro-inverters directly into the back of each of their panels. The array's micro-inverters run in parallel with each other, just as Christmas lights that run in parallel stay lit even if one bulb goes out. Micro-inverters are thus more efficient, as the electricity they produce is the sum of all the different panels rather than the percentage of the least efficient one. But micro-inverters are also more expensive. Silicon Solar Cells Treehugger / Alex Dos Diaz The core of a solar panel is the individual photovoltaic (PV) cells that are connected together to generate electricity. About 95% of PV cells manufactured today are made of silicon wafers, the thin slices of silicon that are used as semiconductors in all electronics. The silicon in those wafers is shaped into crystals with a positive and a negative charge so that energy from the sun gets converted into an electrical current. Those crystals come in two main types—monocrystalline and polycrystalline. You can often tell the difference between the two because monocrystalline panels are black-colored while polycrystalline panels are blue. As with inverters, different PV cells have different efficiencies and different costs. As their name suggests, monocrystalline silicon wafers have a single crystal structure. By contrast, polycrystalline silicon is made from different fragments of silicon crystals fused together. It is easier for electrons to move around in a single crystal structure than it is for them to move in the more ragged structure of a polycrystalline structure, making monocrystalline wafers more efficient in producing electricity. On the other hand, it is easier to fuse crystal fragments together than to carefully slice a single crystal structure, meaning monocrystalline cells are more expensive. Again, as with inverters, higher efficiency leads to higher costs. Newer Solar Cell Technologies One of the limits of silicon wafers is the maximum efficiency with which silicon can convert sunlight into electricity. In solar panels available today, that efficiency stands at under 27%. Bifacial solar panels—with solar cells facing both front and back of the panels—are becoming increasingly popular, because they can generate up to 9% more electricity than single-sided panels, but they are better suited for ground-mounted solar arrays rather than for rooftops. Research is also underway to use new combinations of materials to create more efficient panels and make them commercially available. Perovskites or organic PV cells may reach commercialization soon, while more inventive methods such as artificial photosynthesis show promise but are still in earlier stages of development. Research in the lab continues to produce increasingly efficient PV cells, and bringing that research to market is key to the future of solar technology. Solar Panel Manufacturing Quality matters. A highly efficient panel is worth little if the manufacturer uses inferior wiring and a panel catches fire. The independent Renewable Energy Test Center tests the quality of solar panels from different manufacturers and puts out an annual PV Module Index Report. Its top five performers for “high achievement in manufacturing” for 2022 were (alphabetically): Hanwha Q CELLS, JA Solar, Jinko Solar, LONGi Solar, and Trina Solar. Frequently Asked Questions What are the three types of solar panels? There are three common types of solar panel: monocrystalline (made from a single crystal), polycrystalline (made from multiple crystals), and thin film (flexible and made without crystalline wafers), with monocrystalline having the highest efficiency rating (about 20%) of the three. Where are solar panels made? Solar panels are made all over the world. China is the leading producer, home to seven of the top 10 solar panel manufacturers. Others may be produced in South Korea and Canada but with materials imported from all over the globe. The U.S. is home to a handful of solar companies that do their manufacturing domestically, including Tesla, First Solar, Solaria, LG Solar, and Mission Solar. Are solar panels recyclable? Almost all parts of solar panels can be recycled, but the recycling process requires such specialized and expensive equipment that few depots accept them. According to the Environmental Protection Agency, only five states have solar panel end-of-life policies. The U.S. lacks a national network for solar panel recycling, but the Solar Energy Industries Association has a National PV Recycling Program used by many manufacturers across the country. Originally written by Emily Rhode Emily Rhode Emily Rhode is a science writer, communicator, and educator with over 20 years of experience working with students, scientists, and government experts to help make science more accessible and engaging. She holds a B.S. in Environmental Science and an M.Ed. in Secondary Science Education. Learn about our editorial process View Article Sources "Solar Integration: Inverters and Grid Services Basics." U.S. Department of Energy. "PV Cells 101: A Primer on the Solar Photovoltaic Cell." U.S. Department of Energy. "Monocrystalline and Polycrystalline Solar Panels: What You Need to Know." EnergySage. Bhattacharya, Sayak and Sajeev John. "Beyond 30% Conversion Efficiency in Silicon Solar Cells: A Numerical Demonstration." Scientific Reports, vol. 9, 2019, 12482., doi:10.1038/s41598-019-48981-w Deline, Chris, et al. "Understanding Bifacial Photovoltaics Potential: Field Performance." National Renewable Energy Laboratory, 2019. "PV Module Index 2022 Awardees." Renewable Energy Test Center. "Types of Solar Panels." EnergySage. "Top 10 Solar Companies and Manufacturers in 2022." EnergySage. "End-of-Life Solar Panels: Regulations and Management." Environmental Protection Agency.