Solar Module Manufacturing: Hand Soldering to ABB

Solar module manufacturing turns thin, brittle silicon cells into a sealed panel that has to survive 25 years or more on a roof or in a field. Each module is a stack of glass, plastic film, soldered cell strings and a back sheet, laminated under heat and fitted with a frame and a junction box. Most of that work was once done by hand. This post follows module making from hand soldered cells to automated stringers and laminators, looks at new factories opening in 2026, and covers where ABB robots fit on the factory side. Our earlier post on solar panel installation covers what happens after the modules leave.

Many different solar modules side by side on outdoor test racks. Photo: U.S. Department of Energy via Wikimedia Commons (public domain)

How the first solar modules were built by hand

Bell Labs announced the silicon solar cell in 1954, and its first big customer was space. The US satellite Vanguard 1, launched in 1958, carried small solar cells to power one of its radios. Cells for satellites were made in small batches and wired by skilled technicians, and cost hardly mattered. Down on the ground the same technology was far too expensive for power plants. Panels went to places with no grid at all, such as navigation buoys, remote radio repeaters and later oil platforms, where a battery recharged by the sun was cheaper than sending a crew.

A technician with a satellite covered in solar cells, around 1960. Photo: Unknown author via Wikimedia Commons (public domain)

Early terrestrial modules were built almost entirely by hand. A worker laid out round or square cells, soldered thin copper ribbons from the front of one cell to the back of the next, and repeated the joint dozens of times for each string. The strings were then placed on glass, covered with encapsulant and sealed. Hand soldering is still how hobbyists build small panels today, and it shows why the job was hard to scale: each joint heats a fragile wafer, and a cracked cell can ruin the whole string. US module production has gone through repeated boom and bust cycles since the early 1970s.

Soldering a copper ribbon onto solar cells by hand. Photo: t3xt / Wikimedia Commons (CC0)

Machines took over the most delicate step first. Tabber stringer machines solder ribbons to cells and link them into strings automatically, with cameras checking position and quality. Laminators replaced hand sealing with a vacuum press that heats the stack until the encapsulant melts and bonds. Some firms went further: United Solar Ovonic ran a roll to roll line with 30 MW of annual capacity in 2008, depositing thin film solar layers on long steel strips instead of handling separate wafers. In crystalline silicon factories, the moves between machines were where robots and gantries started to appear.

United Solar Ovonic's roll to roll thin film solar production line with 30 MW annual capacity, 2008. Photo: NREL via Wikimedia Commons (public domain)

New module factories and where ABB robots fit

Module factories are being built again. In the second quarter of 2026, cumulative US module production passed 100 GW, according to an analysis published by pv magazine USA ahead of the Solar Manufacturing USA conference in Austin on 22 and 23 September. Sirius PV, which makes all black residential modules at a 1 GW factory in Brookshire, Texas, told the same magazine in September that it runs its plant on an in-house execution system with an AI monitor that tracks productivity, materials and tax credit compliance.

Breaking ground for First Solar's new factory in Walbridge, Ohio, with US Labor Secretary Marty Walsh, August 2021. Photo: US Department of Labor / Wikimedia Commons (CC BY 2.0)

Europe is adding plants too. On 2 October 2026 Balkan Green Energy News reported that VESS Modules had opened a fully automated 1 GW module factory in Kardzhali, southern Bulgaria, described as the first plant of that size in the European Union. The investment was 15 million euros and created 200 jobs, with plans to grow to 3 GW. The site will also offer practical training in electronics and robotics. In plants like these, robots and gantries load glass, lay cell strings onto it, place junction boxes, fit frames and stack finished modules.

A researcher laminates a mini PV module to test encapsulant materials at Fraunhofer CSE in Boston, 2014. Photo: Robert Terry, U.S. Department of Energy via Wikimedia Commons (public domain)

ABB robots already handle solar products. An ABB IRB 6700 lifts large solar modules for dhp technology's folding solar roofs, and ABB robots work on Absolicon's solar collector line in Sweden, which builds thermal collectors with similar glass and frame handling. For a module line, an IRB 6700 or IRB 4600 could move glass and finished panels, smaller arms such as the IRB 1300 could fit junction boxes, and IRB 460 or IRB 660 palletizers could stack packed modules. We found no public source naming ABB as the robot supplier for a specific PV module factory, so treat these as possible fits.

An ABB IRB 6700 lifts a solar module for a folding roof at dhp technology. Photo: ABB

Where solar module manufacturing goes next

Home buyers mostly see this change through price and quality. Factory automation helped bring module prices down far enough that rooftop panels became an ordinary home purchase, and automatic inspection catches cracked cells before a panel reaches a roof. New cell designs push the factories further. Heterojunction and other high efficiency cells use thinner wafers and lower temperature joints, which leaves less room for rough handling and makes gentle, repeatable robot motion more useful than before.

Solar cells laid out and soldered into strings by hand for a homemade panel. Photo: t3xt / Wikimedia Commons (CC0)

For factories, the next step is fewer manual touches between machines. That means robots that pick strings without bending them, vision that checks every layup before lamination, and software that ties each module back to its cells for warranty and tax credit records, as Sirius PV already does. Engineers can plan these cells and check reach and cycle time in simulation first, the way lines are built in RobotStudio, which matters when a line has to start producing within months of a factory opening.

An ABB robot on Absolicon's solar collector line in Sweden. Photo: ABB

Costs and politics are the biggest unknowns. A 1 GW line is cheap compared with a cell or wafer plant, but module makers compete with very large Asian producers, and US factories depend on tax credit rules that keep changing. Heavy glass and hot laminators still call for guarded cells, though the safety risks are lower than in a foundry or a press shop. Finding people may be harder. New factories need technicians who understand both solar processes and robot maintenance, which is why VESS is pairing its Bulgarian plant with robotics training.

Using an AR headset to check a robot cell before it is built. Photo: ABB

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