Gallium in Solar Energy: CIGS Thin-Film Panels and Concentrated Photovoltaics

Solar Technologies Using Gallium at a Glance

What Role Does Gallium Play in Solar Energy Production?

Gallium serves two solar roles: as a bandgap-tuning element in CIGS thin-film cells - where it raises open-circuit voltage and efficiency - and as the base semiconductor in multi-junction GaAs CPV cells that reach 39%-47% efficiency under concentrated sunlight. Silicon-dominant solar uses no gallium.

CIGS stands for copper indium gallium selenide (chemical formula CuIn_xGa_(1-x)Se₂). Gallium's role is structural and electrical: it widens the material's optical bandgap compared to pure copper indium selenide (CIS), increasing the voltage produced per photon absorbed. A Ga/(Ga+In) ratio of approximately 0.30 yields a bandgap of 1.1-1.2 eV - closely matching the solar spectrum for maximum single-junction efficiency. Gallium is also cheaper than indium, so higher gallium ratios reduce material cost.

In GaAs CPV systems, gallium arsenide forms the active junction in multi-junction cells designed to capture a broad range of the solar spectrum. Each sub-cell targets a different wavelength band, stacking up to 6 junctions to convert photons that a single-junction cell would waste as heat.

What Is a CIGS Solar Cell and How Much Gallium Does It Contain?

A CIGS solar cell is a thin-film semiconductor device deposited on a glass, metal, or polymer substrate. The active layer - typically 1-3 micrometers thick - contains copper, indium, gallium, and selenium in a ratio where gallium makes up 27%-40% of the combined gallium-plus-indium content. This gallium fraction sets the bandgap and directly controls the efficiency ceiling.

CIGS cells weigh grams per square meter, not kilograms, making them lightweight enough for building facades, curved roofing, and flexible portable panels. The thin active layer means total gallium mass per panel is small - but purity requirements are high. Gallium in CIGS manufacturing must reach at least 6N (99.9999%) purity to prevent crystal defects that lower voltage and increase recombination losses.

The CIGS absorber layer is deposited by co-evaporation or sputtering, then covered with a cadmium sulfide buffer layer and a transparent zinc oxide front contact. The total stack thickness is under 5 micrometers - roughly 100 times thinner than a human hair.

How Efficient Are CIGS Solar Panels Compared to Silicon?

CIGS panels reach 23.64% in laboratory cells (2024 record, Uppsala University in collaboration with First Solar's research division) and 12%-17.6% in commercial production. Monocrystalline silicon reaches 26.7% in laboratory conditions and 20%-23% in commercial modules. The 3-11 percentage point commercial gap reflects silicon's 50-year manufacturing head start, not a fundamental physics limit.

The 2024 CIGS record was set using a silver-rich absorber with a tailored gallium depth profile - high gallium concentration near the back contact, lower concentration near the buffer layer. Researchers indicated that eliminating parasitic absorption in the window and buffer layers could push CIGS past 25% efficiency.

Why Is CIGS Preferred for Building-Integrated Photovoltaics?

CIGS is preferred for building-integrated photovoltaics (BIPV) because it can be deposited on flexible, lightweight substrates and tuned to semi-transparent configurations for facades and glazing. Silicon panels are rigid, heavy, and visually intrusive. A CIGS module deposited on a stainless steel or polymer backing weighs under 5 kg/m² versus 10-12 kg/m² for framed silicon panels.

The global BIPV market reached USD 23.67 billion in 2023 and is projected to hit USD 89.8 billion by 2030, at a CAGR of 19.7%-20.4%. Europe holds 43.40% of BIPV market revenue (USD 10.1 billion in 2024), driven by building energy codes requiring renewable integration. Over 1.3 million buildings globally incorporated BIPV solutions in 2024, up from 900,000 in 2020.

CIGS BIPV Product Types

The glass segment is the fastest-growing BIPV category, driven by demand for transparent photovoltaics in modern commercial buildings. Rooftop applications account for 48.9% of 2024 BIPV market revenue. CIGS low-light performance matters in BIPV because facades face north or receive shade for portions of the day - CIGS maintains relative output in diffuse conditions better than silicon, improving annual energy yield on suboptimal orientations.

What Is Concentrated Photovoltaic Solar and How Does Gallium Arsenide Enable It?

Concentrated photovoltaic (CPV) solar uses lenses or mirrors to focus 200x-1000x the normal sunlight onto a small area of multi-junction GaAs cells. This concentration allows the cells to operate at efficiencies impossible in standard flat-panel designs - commercial CPV systems reach 36%-39% efficiency at 500x-1000x concentration versus 20%-23% for the best silicon panels.

GaAs enables CPV through its multi-junction structure. A standard triple-junction cell stacks three semiconductor layers: an indium gallium phosphide top junction (absorbing blue/green light), a GaAs middle junction (absorbing red light), and a germanium bottom junction (absorbing infrared). Each junction converts its target wavelength band to electricity, and the three outputs add together. Adding more junctions increases efficiency further - current records use 6 sub-cells.

CPV systems require direct normal irradiance (DNI) - the beam component of sunlight - and two-axis tracking to maintain lens alignment. This limits CPV deployment to high-DNI regions (Southwest U.S., MENA, Atacama Desert) and narrows its application to utility-scale plants in those zones.

Active CPV companies include Spectrolab (Boeing subsidiary), Azur Space Solar Power (part of 5N Plus since 2021, 50+ years GaAs experience), and EMCORE. The GaAs components for CPV cells share manufacturing heritage with the satellite solar cell supply chain covered on the gallium in aerospace applications page.

Which Companies Manufacture CIGS Solar Panels?

Five companies dominate CIGS thin-film production: Solar Frontier (Japan, ~1 GW annual capacity), Midsummer (Sweden, 200 MW factory under development), MiaSole (U.S., Hanergy-owned, 17.44% commercial efficiency record), Avancis GmbH (Europe), and Hanergy Group (China, owner of Solibro CIGS IP). Solar Frontier held the previous CIGS efficiency record at 23.35% (2019) before Uppsala University set 23.64% in February 2024.

For upstream gallium supply that feeds these manufacturers, see the gallium producers page and gallium refining and purity grades.

How Much Gallium Does the Solar Industry Consume?

CPV systems require 2-3 tonnes of ultra-pure gallium per GW of installed capacity. CIGS thin-film uses gallium in grams per module but at scale requires significant refined gallium. Total solar sector gallium demand is modest relative to gallium's other industrial uses and has been declining within silicon-based solar cells since 2023.

The decline in silicon-cell gallium demand is structural: the global solar industry shifted from PERC (passivated emitter and rear cell) technology to n-type TOPCon cells. PERC silicon cells used gallium doping to reduce a defect called light-induced degradation (LID). TOPCon cells use a different architecture that does not require gallium doping, effectively ending gallium consumption in silicon solar cell manufacturing as the industry transitions.

The CIGS market reached USD 1.7-3.81 billion in 2024 (estimates vary by scope) and is projected to grow at CAGR 17.8%-22.5% through 2030-2033. The CPV segment grew from a smaller base to USD 2.88 billion in 2024. Neither replaces the gallium demand that PERC doping once generated in silicon cells.

For context on how gallium pricing responds to these demand shifts, see the gallium price history page.

How Do China's Export Restrictions Affect Gallium Supply for Solar Manufacturers?

China produces 98% of global low-purity gallium and supplies 95% of U.S. gallium imports. The December 2024 ban on gallium exports to the United States - suspended in November 2025 until November 2026 - cut the primary supply route for CIGS and GaAs solar cell manufacturers dependent on Chinese gallium. Gallium sold outside China was trading at nearly double the Chinese domestic price by early 2024, before the full ban took effect.

CIGS manufacturers face a more direct exposure than silicon solar producers because CIGS cells physically contain gallium in the active layer - a ban cannot be routed around through process changes. GaAs CPV manufacturers face the same constraint: GaAs wafer growth requires 6N+ gallium with no substitution possible at current technology levels.

See the China export ban page for the policy timeline from August 2023 through the 2025 suspension. The gallium supply chain risks page quantifies Western production capacity versus total demand across all sectors including solar. For investment implications, see the gallium investing overview.

Gallium in Solar Energy: Quick Reference

Gallium's solar role is narrow but structurally important in two growing markets: CIGS thin-film for BIPV and flexible installations, and GaAs CPV for high-efficiency concentrated systems. The PERC-to-TOPCon shift removed gallium from the 95% silicon solar majority, concentrating gallium demand in the segments where efficiency and form factor justify the cost premium. As BIPV demand grows with building energy regulations and CIGS manufacturing scales in Europe and Asia, gallium consumption from the terrestrial solar sector will recover from the PERC phaseout - but supply chain security remains the defining challenge for manufacturers outside China's production sphere.