How Do You Manufacture Solar Energy?
Solar energy is the radiant energy from the sun that is harnessed using various technologies such as solar heating, photovoltaics, and concentrated solar power. The manufacturing process for solar panels involves creating silicon ingots, cutting them into wafers, assembling solar cells from the wafers, connecting the cells into panels, framing the panels, and testing them before shipment and installation.
Solar energy has several important benefits. As a renewable energy source, solar power reduces dependence on fossil fuels and decreases greenhouse gas emissions that contribute to climate change (https://www.energy.gov/eere/solar/solar-energy-wildlife-and-environment). Solar energy systems can lower electricity bills for homes and businesses by generating power on-site (https://www.constellation.com/energy-101/energy-innovation/solar-energy-pros-and-cons.html). Solar power also provides energy independence and security by reducing reliance on the grid. Overall, solar energy has become an important clean energy source for the future (https://www.empower-solar.com/en/blog/why-choose-solar-importance-of-solar-energy-empower-solar/).
History of Solar Panel Manufacturing
Solar panels have been around for over half a century. According to the Wikipedia article on Solar Panels, the first commercially viable silicon solar cell was created in 1954 by Bell Labs [1]. This groundbreaking invention paved the way for solar technology as we know it today.
The real beginning of solar panel manufacturing started in the 1950s when Bell Laboratory scientists focused their research on photovoltaic (PV) technology and began using silicon to produce solar cells [2]. However, it wasn’t until the energy crisis of the 1970s that interest and development in solar technology really took off. With rising oil prices, there was increased demand for alternative energy sources like solar.
Key innovations that drove advances in solar panel manufacturing include the development of the silicon cell in 1954, the creation of the first solar-powered building “Solar One” in 1973, and improvements in panel efficiency and cost reduction in the 1990s and 2000s [3]. Today, solar panels are a mature technology deployed worldwide as a clean, renewable energy source.
Manufacturing Silicon
Silicon, which makes up the bulk of a typical solar panel, must go through an intensive refining and purification process before it can be used in panel production. The raw material for solar-grade silicon is metallurgical-grade silicon (source). This is usually made from quartz rock which is put through an electrochemical process to extract the silicon. The metallurgical silicon contains impurities so it goes through a purification process to increase its purity. This involves a chemical vapor deposition method where gaseous compounds containing silicon are decomposed at high temperatures, depositing ultra pure solid silicon onto rods. This results in polycrystalline silicon rods known as ingots. The ingots are then sawn into wafers which form the base of solar cells.
Ingot & Wafer
Silicon ingots are cast from molten silicon in a process known as Czochralski growth. In this process, polysilicon is melted in a quartz crucible and a small single crystal silicon seed is slowly pulled while being rotated, allowing the silicon to crystallize around it forming a cylindrical ingot up to 2 meters in length and 30cm in diameter (1). The ingots are then squared off to remove defects on the surface. Squaring reduces the diameter to around 20cm (2).
The silicon ingots are sliced into wafers using wire saws. The ingot is fixed in place while a steel wire coated in slurry saws through the ingot, slicing many wafers simultaneously. Wafers are typically 180-200 microns thick. The wafers are then cleaned, etched, and polished to remove surface damage and contaminants from the sawing process (2).
The resulting monocrystalline silicon wafers serve as the substrate for solar cells in photovoltaic modules (1).
Sources:
(1) https://pv-manufacturing.org/silicon-production/wafering/
(2) https://www.linkedin.com/pulse/solar-wafer-manufacturing-powering-future-sunlight-codedata
Cell Fabrication
Silicon wafers are processed into individual solar cells by adding electrical contacts and passivation layers. The first step is texturing the wafer surface through chemical etching, which removes saw marks and creates a rough surface to help trap light (Solar Photovoltaic Manufacturing Basics). Next, an anti-reflective coating like silicon nitride is applied to the front, reducing reflection.
On the front of the cell, a metal contact grid called fingers and busbars are screen printed. These transport current produced by the cell. The back of the cell also gets a full-area metal contact applied through screen printing, sputtering, or evaporation. The front and back contacts enable the cell to collect and output electricity.
After metallization, an electrical isolation layer like silicon nitride is added to passivate or protect the surface. Passivation restricts surface recombination, which improves current collection. The edges of the cell may also be trimmed at this stage. Finally, electrical tests are performed to discard underperforming cells (How Are Solar Cells Made?). This entire fabrication process turns raw wafers into functioning solar cells ready for module assembly.
Panel Assembly
The solar cells are assembled into complete solar panels during the panel assembly process. First, the solar cells are layered and laminated between sheets of clear tempered glass, ethylene vinyl acetate (EVA) plastic, and a polymer backing sheet to encapsulate and protect the cells (Solar Photovoltaic Manufacturing Basics).
The panel frame is constructed of aluminum and attaches to the backing sheet to provide additional mechanical support. Electrical wiring connects the solar cells into strings and combines the cell strings into a junction box on the back of the panel. Bypass diodes are also wired across the cell strings to allow current to continue flowing in the event a cell is shaded or damaged (The Process of Solar Panel Manufacturing).
The glass surface is treated with an anti-reflective coating to maximize light absorption. The completed solar panel is inspected visually and electrically tested before being sent for certification.
Testing & Certification
Once solar panels are manufactured, they must undergo rigorous testing and certification to ensure they meet industry standards for safety, durability, and performance. There are several major testing laboratories that manufacturers utilize:
Underwriters Laboratories (UL) provides UL 1703 certification, which evaluates electrical shock, fire, and other hazards associated with PV modules (source). Modules must pass tests like dielectric withstand, wet insulation resistance, and bypass diode thermal tests.
TÜV Rheinland provides IEC 61215 and 61730 certifications, which evaluate performance and safety respectively. Tests cover areas like UV exposure, damp heat, mechanical loading, and hot-spot endurance (source).
NABCEP is the most widely recognized certification for solar installers in North America. Installers must pass an exam demonstrating their knowledge of solar PV systems to receive the NABCEP PV Installation Professional Certification (source). This ensures quality workmanship.
Reputable manufacturers will indicate all the certifications their panels hold to provide transparency around quality control testing procedures and standards.
Mounting Equipment
Mounting equipment is essential for properly installing solar panels and connecting them to the electrical system. The main components are the racking system, trackers, and inverters.
Racking refers to the mounting structure that securely attaches solar panels to rooftops or the ground. Aluminum and galvanized steel are common racking materials, chosen for their durability and corrosion resistance. Fixed tilt and tracker racking systems are available. Fixed tilt mounts hold panels at a set angle, while trackers move panels to follow the sun’s path for increased energy production (Source 1).
Trackers are automated systems that orient solar panels to maximize solar energy capture. Single-axis trackers rotate panels along one axis, following the sun east to west. Dual-axis trackers follow the sun’s daily and seasonal movement for optimal alignment. Trackers boost energy output but cost more than fixed mounts (Source 2).
Inverters convert the DC electricity from solar panels into usable AC power for buildings and the grid. Central inverters connect to multiple panels, while microinverters convert energy at each panel. Inverter selection depends on the system size and site specifics (Source 3).
Installation
Properly installing solar panels is crucial for safety and performance. Installation typically involves securely mounting the solar panels on rooftops or ground-mounted racks. Here are some key steps for safe and effective installation:
Rooftop Installation
– The roof must be assessed to ensure it can structurally support the weight of the solar array. Rooftops may need reinforcement.
– Mounting equipment like rails and brackets are secured to the roof using lag bolts anchored to roof rafters. Flashing is used to seal roof penetrations.
– Solar panels are then mounted and secured to the rails and brackets. Proper spacing is important to avoid shading.
– Wiring connects the panels into strings and arrays. Conduit runs wiring through the house to the inverter and meter.
– Safety harnesses and fall protection are essential when working on rooftops.
Ground-Mounted Arrays
– Concrete foundations or driven piles are used to support the mounting structure.
– Aluminum or galvanized steel poles are erected and anchored to the foundations.
– Solar panel mounting racks are then attached and secured to the poles.
– Solar panels are mounted and spaced appropriately to minimize shading.
– All electrical connections, conduits and wiring are completed.
– Safety measures like perimeter fencing help secure the installation.
Proper installation by qualified technicians ensures solar arrays are mounted securely, generate optimal electricity, and operate safely for decades.
Conclusion
In summary, solar panel manufacturing has come a long way since its inception in the 1950s. Advances in silicon purification, wafer slicing, cell fabrication, and panel assembly have driven down costs and increased efficiency dramatically. Today’s solar panels convert over 20% of sunlight into electricity, compared to just 4% in the 1950s.
The future looks bright for solar panel manufacturing innovations like perovskite solar cells. Combining perovskites with silicon solar cells in tandem configurations could push efficiencies over 30%. New manufacturing techniques like roll-to-roll processing may lower costs further. Ultimately, the goal is to make solar energy competitive with fossil fuels across the globe.
The environmental and economic benefits of solar panel manufacturing and renewable energy adoption are immense. Solar energy could drastically reduce greenhouse gas emissions, air pollution, and reliance on imported fuels. With climate change accelerating, scaling solar panel production and installation is imperative. The solar industry’s continued growth and development offers hope for a more sustainable energy future.
