How Are Solar Panels Made? (2023)

Leonardo David is an electromechanical engineer, MBA, energy consultant and technical writer. His energy-efficiency and solar consulting experience covers sectors including banking, textile manufacturing, plastics processing, pharmaceutics, education, food processing, real estate and retail. He has also been writing articles about energy and engineering topics since 2015.

Tori Addison is an editor who has worked in the digital marketing industry for over five years. Her experience includes communications and marketing work in the nonprofit, governmental and academic sectors. A journalist by trade, she started her career covering politics and news in New York's Hudson Valley. Her work included coverage of local and state budgets, federal financial regulations and health care legislation.

Solar panels have become more efficient and affordable over time — between 2010 and 2022, the efficiency of photovoltaic (PV) modules increased from 14% to more than 22%. These improvements in solar technology have been possible thanks to innovation and large-scale investment in manufacturing processes, but how exactly are solar panels made?

In this article, we at the MarketWatch Guides Team discuss the solar panel manufacturing process step-by-step, from the initial phases to assembly, testing and the environmental impacts.

Most solar PV modules use silicon solar cells, which you can classify into two main types: monocrystalline and polycrystalline. Both types of PV cells are made of high-purity silicon but have different manufacturing processes:

Monocrystalline solar panels can convert sunlight into electricity more efficiently but are more complex and expensive. Polycrystalline solar panels are easier to make and more affordable but have a lower efficiency.

The technical details of solar panel manufacturing are complex, but we break down each step in the process in the following sections. The steps below apply to crystalline silicon solar panels, which represent over 90% of the global market share. Other panel types, including thin-film panels, have different manufacturing processes depending on the material.

According to the Royal Society of Chemistry, silicon is one of the most abundant elements on Earth, making up 27.7% of the planet’s crust. However, naturally occurring silicon is combined with other elements such as oxygen, phosphorus and nitrogen. Manufacturers must process these raw materials to obtain the pure silicon required to make solar panels.

The oxygen content of mineral silica can be removed with high temperatures, which results in high-purity silicon. The solar industry uses 99.9999% pure polysilicon to manufacture both polycrystalline and monocrystalline solar cells.

Poly cells have a more straightforward production process that involves casting and cutting polycrystalline silicon blocks into the square wafers used to make PV cells.

Making mono cells is more complex since solar manufacturers must first ensure the molten silicon solidifies into a single crystal. The process relies on the Czochralski method, in which crystals are “grown” by dipping a smaller “seed crystal” in molten silicon. The result is a large cylindrical block made of a single silicon crystal that manufacturers can cut into solar cells.

Manufacturers can improve the efficiency of PV cells by adding controlled amounts of boron and phosphorus. Solar panel efficiency measures the amount of sunlight a solar cell can convert into energy.

The added elements act as semiconductors — phosphorus results in n-type silicon, while boron results in p-type silicon.

In other words, this process converts sunlight into electric power.

Solar panels consist of multiple PV cells connected together using silver conductors and copper solder. There are many panel sizes, but most residential solar panels have 60 or 72 cells. Some manufacturers make solar panels with 120 or 144 half-cells, which have roughly the same dimensions as 60 and 72-cell panels.

Manufacturers cover the PV cells with an anti-reflective coating to increase sunlight absorption. Solar panels are also encapsulated by two layers of ethylene vinyl acetate (EVA), which helps to protect the panels from dust and humidity. The final assembly includes covering the panel with a frontal tempered glass sheet and polymer backsheet.

As previously mentioned, solar panels use an array of PV sheets encapsulated by polymer layers. The front of a panel is covered by a translucent tempered glass sheet, while the rear is covered by a backsheet made of weather-resistant plastic. Finally, a rigid aluminum frame holds the solar panel together for structural support.

The backsheet also includes a junction box that contains the electrical terminals used to wire solar panels together. Installers can connect PV modules into string circuits with a common inverter, or equip each panel with individual microinverters.

All manufacturers use the same laboratory conditions to test solar panel wattage and efficiency. The Standard Test Conditions (STC) include the following guidelines:

Companies also test solar panels against hail impact, hurricane winds and other harsh weather conditions. High-quality modules are designed to withstand hailstones with a 1” diameter traveling at 50 mph, and winds of up to 140 mph. Many residential solar panels have a 25-year manufacturer warranty and can last for more than 40 years with regular cleaning.

According to a study by the National Renewable Energy Laboratory (NREL), the lifetime carbon footprint of a solar power system is 50 grams of CO2 equivalent per kilowatt-hour of electricity produced. The study considers the entire life cycle of solar panels, including raw materials extraction, manufacturing, transportation, construction, operation and decommissioning.

This is only a small fraction of the emissions generated by fossil fuel power plants:

All manufacturing processes that require energy and raw materials have an environmental impact, including solar modules and other clean energy technologies. However, renewable technologies have a lower lifetime impact than fossil fuel power stations.

Solar panel installations are growing among U.S. homeowners. According to the Solar Energy Industries Association (SEIA), more than 700,000 home solar systems were installed nationwide in 2022. But you may be wondering how solar panels work, and what they are made of.

The two main types of panels use solar cells made of high-purity silicon, but there are important differences in the manufacturing processes. As a result, monocrystalline panels offer a higher energy conversion efficiency for an increased price, while polycrystalline panels are more affordable.

Companies also test solar panel systems under controlled lab conditions to measure wattage and efficiency — both of which influence quality and cost. The average solar power system costs $2.85 per watt or $14,250 for a 5 kilowatt (kW) system and $28,500 for a 10 kW system. You can reduce your overall price by claiming solar incentives like the federal solar tax credit.

Purchasing high-quality solar panels is key if you want to achieve long-term energy savings. Even the best solar panels can perform poorly if not installed properly, and most manufacturers will void your warranty if there is evidence of an incorrect installation. The best solar companies can help you purchase and install solar panels that meet your home’s energy needs and budget.

Monocrystalline and polycrystalline solar panels are made of high-purity silicon, which does not occur naturally. Silica and other minerals with a high silicon content are mined and processed to create solar-grade polysilicon.

Thin-film solar panels use a wide range of materials including amorphous silicon, cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS). Manufacturers create thin-film panels by applying these materials as a thin layer on rigid or flexible surfaces.

Some solar panel components are processed from fossil fuels, including the EVA encapsulant and backsheet. PV module manufacturing also uses large amounts of energy, which may come from fossil fuels depending on the local power source.

According to the U.S. Department of Energy, the country produced five gigawatts (GW) — or 5 million kW — of solar panel capacity in 2022. The agency does not provide the exact number of solar panels manufactured in the country. Assuming an average panel size of 400 watts, 5 GW is equivalent to more than 12 million solar modules.

The number of solar panels you need will vary depending on your energy consumption. Considering the average U.S. household consumes 886 kWh of electricity per month (or 10,632 kWh of electricity per year), you would need 15 to 20 solar panels. However, your needs may differ. We recommend working with a professional solar installer to determine the exact number of solar panels you need to power your home.

Leonardo David is an electromechanical engineer, MBA, energy consultant and technical writer. His energy-efficiency and solar consulting experience covers sectors including banking, textile manufacturing, plastics processing, pharmaceutics, education, food processing, real estate and retail. He has also been writing articles about energy and engineering topics since 2015.

Tori Addison is an editor who has worked in the digital marketing industry for over five years. Her experience includes communications and marketing work in the nonprofit, governmental and academic sectors. A journalist by trade, she started her career covering politics and news in New York’s Hudson Valley. Her work included coverage of local and state budgets, federal financial regulations and health care legislation.