Evolution of Solar Modules: Which Technology Leads the Future?
Solar photovoltaic (PV) technology has improved dramatically over the past decades, driven by innovation and scale. Research-cell efficiencies have jumped from ~15% in the 1970s to over 47% for advanced multi-
junction devices shipped in 2024
1 . At the same time, global PV deployments have exploded (a record ~703 GW of modules
2 ) and module prices have fallen to a few U.S. cents per watt. Figure 1 (NREL data)
illustrates the historical rise in cell efficiency across technologies . Today, the industry’s workhorse is PERC silicon cells, but new technologies (TOPCon, HJT, tandem) are gaining ground by pushing efficiency higher. The following sections examine each technology in turn, highlighting how they work, their pros and cons, and current market trends.
Figure 1: Historical record PV cell efficiencies for various technologies . Silicon-based cells (blue) have steadily improved, but advanced multijunction and tandem cells (pink/orange) now lead in peak efficiency.
PERC (Passivated Emitter and Rear Cell)
Figure 2: Cross-section of a PERC silicon solar cell. A dielectric passivation layer on the rear reflects unabsorbed light back into the cell .
PERC cells are based on p-type crystalline silicon and add a rear passivation layer (typically aluminum oxide) behind the emitter. This “passivated emitter and rear cell” structure reflects unused photons back through the silicon and reduces carrier recombination at the rear contact, boosting efficiency by up to ~10–12% over plain cells . In practice, modern PERC modules routinely achieve ~22% efficiency. The cell process is well understood and low-cost, requiring only a few extra steps (rear Al deposition and laser opening of contacts) on conventional lines. Key traits of PERC technology include:
• Advantages: PERC is simple and inexpensive to manufacture. It has been the dominant industrial cell technology since the mid-2010s . The rear dielectric layer increases photo-current without major process overhaul, allowing many manufacturers to improve efficiency on existing equipment
. PERC modules also tolerate conventional silicon wafer grades and benefit from economies of scale, yielding very low $/W.
• Disadvantages: PERC on p-type silicon is approaching its efficiency limits (~22–23% in production)
. P-type wafers suffer from light-induced degradation (LID) of a few percent, and further efficiency gains now require harder-to-implement cell designs. Silver front contacts (standard in PERC) remain expensive, and most new efficiency ideas (half-cells, multi-busbars, black silicon, etc.) have yielded only incremental gains.
• Market Trends: PERC modules once accounted for the vast majority of PV shipments, but their share is now declining. For example, PERC represented ~50% of leading module products in early 2023, dropping to ~38% by late 2024 as manufacturers transitioned to n-type technologies . Major suppliers like Tongwei and Jinko have begun delisting PERC products in favor of n-type cells . Nonetheless, billions of PERC panels are already installed worldwide. In markets like utility-scale PV, PERC remains a default choice where cost is paramount.
• Economics & Business Impact: PERC’s low manufacturing cost has driven down PV module prices and expanded deployment. Its mature supply chain keeps capital expenditures and module prices
lowest among crystalline silicon options. However, the plateauing efficiency means higher balance- of-system costs (more area and panels needed per kW) compared to next-generation cells. Developers using older PERC technology may face slight LCOE disadvantages over time as higher- efficiency modules become available.
• Manufacturers & Case Studies: Virtually every module maker ( JA Solar, Jinko, Canadian Solar, Trina, etc.) sold PERC-based products. PERC was essential to past cost reductions. As a case in point, multiple companies (Kalyon, Astronergy, Talesun) recently removed PERC modules from their top- product lists, signaling a shift to superior cell types .
In summary, PERC remains a low-cost workhorse with ~20–22% efficient modules, but it is being overtaken by n-type technologies. Its advantages are well-known, but its future is limited by intrinsic performance ceilings.
TOPCon (Tunnel Oxide Passivated Contact)
Figure 3: N-type TOPCon solar cell structure. A thin silicon dioxide layer (“tunnel oxide”) plus a doped polysilicon film on the rear creates highly passivated contacts .
TOPCon cells build on the PERC concept but use n-type silicon wafers and an advanced rear passivation: a very thin silicon oxide (SiO₂) film (∼1–2 nm) covered by doped polysilicon. This “tunnel oxide passivated contact” structure drastically reduces recombination at the rear, allowing for higher open-circuit voltages and efficiencies . In effect, TOPCon marries low-defect n-type material with enhanced rear field, achieving cell efficiencies in production around 24–26% and theoretical limits ~28–29% . Key points about TOPCon technology:
• Overview: TOPCon is typically made on n-type Czochralski silicon. After forming the n-type emitter on the front, manufacturers deposit an ultra-thin oxide on the rear surface and a highly doped polysilicon layer on top. This creates a “tunneling” contact that passivates the surface while still conducting current . Because n-type silicon has virtually no boron-oxygen defects, TOPCon cells exhibit negligible LID.
• Advantages: The high-quality passivation and n-type base give TOPCon an efficiency and performance edge. The technology achieves higher bifacial gains (>80%) and better low-light output compared to PERC. Crucially, TOPCon is largely compatible with existing PERC lines (many steps are similar), so manufacturers can reuse equipment with moderate upgrades. The result is a path to ~1– 2% higher module output for comparable area.
• Disadvantages: TOPCon requires more processing steps (additional diffusion and several PECVD steps) than PERC, raising capital costs. New TOPCon fabs are roughly 1.5–2× more expensive per GW than PERC lines . Early in ramp-up, cell yields can be lower, and the processes (especially oxide growth and poly-silicon deposition) must be tightly controlled. These factors make TOPCon modules somewhat higher-cost per watt, at least initially.
• Market Trends: A wave of recent market analyses predict TOPCon will dominate in the near term. For instance, China’s PV association projects TOPCon’s share rising from ~23% in 2023 to ~60% by 2024 . Industry trackers like ITRPV report that n-type (mostly TOPCon) wafers now surpass p-type materials, and that TOPCon is overtaking PERC . One forecast sees TOPCon capturing ~70–80% of cell production by 2025 . Indeed, TOPCon production capacity is scaling rapidly – industry data indicate hundreds of GW of new TOPCon factories underway .
• Economics & Business Impact: Higher TOPCon efficiency translates into lower levelized costs over time (more electricity per panel). Models show that although TOPCon modules carry a premium, their superior energy yield (and stability) can drive down LCOE. Module spot prices have fallen as well, partly thanks to TOPCon scale. The learning rate of PV (∼25% cost reduction per doubling of capacity ) suggests TOPCon will help continue the historic trend of falling $/W. Utilities and project developers are keen on TOPCon to squeeze more output from given land or rooftop area.
• Manufacturers & Case Studies: Virtually every major cell-maker has launched TOPCon. Jinko’s “Tiger Neo”, Trina’s Vertex N, and LONGi’s latest products are all TOPCon-based. For example, Trina Solar highlights TOPCon’s potential to boost efficiency toward the silicon ceiling . The module market is responding: by late 2024 many suppliers’ flagship offerings were TOPCon modules. Large investments (e.g. hundreds of MW/GW factories) are being made worldwide to convert or build PERC lines into TOPCon lines.
In summary, TOPCon is currently the “leading” new silicon technology. It offers higher efficiency and stability than PERC with relatively modest process changes. Analysts expect TOPCon to drive the next round of PV cost reductions and to comprise most of the solar-cell market within a few years .
HJT (Heterojunction Technology)
Figure 4: Heterojunction (HJT) solar cell cross-section. A crystalline silicon wafer is sandwiched between thin intrinsic and doped amorphous silicon layers, with transparent conductive ITO contacts .
Heterojunction (HJT) cells combine crystalline silicon with thin-film amorphous silicon. Typically an n-type silicon wafer is coated on both sides with an intrinsic a-Si:H layer and doped a-Si:H (p-type on front, n-type on back), capped by transparent conductive oxides (e.g. ITO) and metal contacts. This “hybrid” structure yields extremely good surface passivation and a strong built-in field. Laboratory HJT cells have reached
~26.7% efficiency; commercial cells and modules are in the 23–24% range. Key aspects of HJT:
• Overview: HJT employs an n-type monocrystalline wafer (often thinner than PERC wafers) and low- temperature deposition of hydrogenated amorphous silicon layers. The intrinsic a-Si:H films serve as perfect passivating layers on both sides . Anti-reflective coatings and transparent conductive layers (ITO or ZnO) complete the structure. Because all processing (PECVD, sputtering) is performed at <200°C, the original silicon bulk sees minimal thermal diffusion.
• Advantages: HJT yields very high efficiencies and excellent performance at high temperatures. The amorphous layers virtually eliminate recombination and shading (contacts are narrower), giving higher Voc and fill factor. HJT cells exhibit virtually no LID and have ultra-low degradation over time. They are inherently bifacial (often >90% bifacial gain). Compared to PERC, HJT’s temperature coefficient is better (loses less power in heat) and it tolerates some impurities better.
• Disadvantages: HJT is capital-intensive. Building a new HJT line requires multiple PECVD reactors (for a-Si deposition on both sides), sputter tools for ITO, and other specialized equipment . Module production also uses more silver (finer grid lines, since contacts only on front) though high bifacial output can offset that. Until now, limited manufacturing experience has kept yield slightly lower. These factors make HJT modules expensive compared to PERC/TOPCon.
• Market Trends: HJT adoption has been modest. Only a few GW of HJT fabs are currently online (mainly in China and Europe). In late 2024, HJT cells accounted for roughly 14–17% of the top-tier module listings . Analysts project HJT share will grow gradually – for example, estimates see HJT
reaching ~10–20% of cell production by around 2030 (depending on adoption of newer architectures). Some market surveys even suggest that advanced back-contact cells (like TOPCon- based or HJT-based IBC) may together challenge HJT’s share.
• Economics & Business Impact: HJT’s high cost means its LCOE benefit is situation-dependent. In cold or low-light climates, its superior energy yield can justify the premium. Large C&I rooftop systems and some utility projects value HJT’s high output per area. The industry is also reducing HJT costs: for example, metallization schemes using copper or printed silver aim to cut material costs. If prices fall, HJT could become competitive for premium segments.
• Manufacturers & Case Studies: Major players in HJT include REC Group (Norway), Tongwei (China), Meyer Burger (Switzerland), and emerging Chinese firms like Huasun. For instance, REC recently launched a commercial “Alpha Pro M” module series using HJT cells rated ~22.5% efficiency . In China, manufacturers like Risen and URECO have begun HJT production. Globally, only a handful of new factories (e.g. Meyer Burger’s US plants) have come online, but more are planned as HJT equipment matures.
In summary, HJT offers the highest realistic silicon efficiencies and outstanding stability, but at higher cost. It is a compelling technology for the long term, and its share is slowly growing, especially in markets prioritizing performance.
Tandem Solar Cells
Figure 5: Configurations of tandem solar cells. Top-cell (wide-bandgap) and bottom-cell (narrower-bandgap) sub- cells can be connected in series (two-terminal tandem) or as separate circuits (four-terminal) .
Tandem (multi-junction) cells stack two or more solar cells with different absorption bands to exceed the efficiency limit of silicon alone. The most mature approach combines a perovskite top cell (bandgap ~1.7 eV) with a silicon bottom cell (1.1 eV). These perovskite/silicon tandems can be built as monolithic two-terminal
devices (current-matched in series) or as mechanically stacked/splitter-separated four-terminal systems . Tandems promise vastly higher efficiency (theoretical Si-perovskite limit ~43%). Key points:
• Overview: A tandem typically has a front cell tuned to high-energy photons and a rear silicon cell for lower energies. Perovskite layers can be processed at low temperatures on top of finished silicon cells. Alternatives include III-V/silicon and CIGS/silicon tandems, but perovskite is leading the push to commercialization. Figure 5 shows various tandem architectures.
• Advantages: By capturing more of the solar spectrum, tandems break the ~33.7% Shockley– Queisser limit for single-junction silicon. Lab tandem cells have already topped 34% efficiency . Tandem modules can deliver 20–30% more energy per roof area. For example, Oxford PV claims its perovskite-silicon modules will generate ~20% more energy over the year than standard silicon modules . In principle, tandems can dramatically reduce LCOE if reliability issues are solved.
• Disadvantages: Tandems are complex and not yet mainstream. Perovskites in particular raise stability and durability concerns (e.g. moisture sensitivity). Manufacturing requires new steps (transparent top contacts, lamination processes) and yields must be proven at scale. Module costs today are high due to specialty materials and processes. Four-terminal tandems (with separate circuits) avoid current-matching issues but need twice as many components and wiring.
• Market Trends: Commercialization is just beginning. Oxford PV (UK) has started delivering small quantities of perovskite/Si modules (~24.5% efficient) to customers . Qcells and other companies have announced pilot products. Despite high expectations, market forecasts keep tandem shares very low through this decade. For instance, leading roadmaps predict tandem tech will first appear above noise around 2029–2030 with only a few percent of market share . In short, tandems remain a niche technology today, though with huge long-term potential.
• Economics & Business Impact: If tandems achieve scale and stability, they can greatly increase energy output per installation, reducing BOS costs (inverters, mounting, etc.) per kW. Early adopters may pay a premium per panel, but gain more annual generation (especially valuable on land- constrained sites). Business models are still forming: Oxford PV emphasizes large ground-mounted systems, while others target premium rooftop or mobile applications.
• Manufacturers & Case Studies: Notable developments include Oxford PV’s commercial perovskite/ Si panels (manufactured in Germany) rated ~24.5% . Qcells (Hanwha) announced a record 28.6% full-area M10 tandem cell , and is working on pilot production. In 2024, LONGi and partners reported a certified 34.6% 2-terminal tandem cell and a 25.8% four-terminal module . (In April 2025 LONGi further set a new record of 34.85% .) In research labs, many teams (NREL, EPFL, KAUST, etc.) are pushing tandem efficiency even higher.
Tandem cells thus stand at the frontier of PV: lab efficiencies are now record-setting, and the first commercial products are emerging, but widespread adoption will take more time. They represent the future promise of photovoltaics, especially as perovskite stability and manufacturing mature.
Conclusion: Future Outlook
In conclusion, the landscape of solar module technology is rapidly shifting. PERC silicon will remain common in the short term but is increasingly being eclipsed. The near-future leader appears to be TOPCon: analysts and roadmaps show it capturing on the order of 70–80% of new cell production by the mid-2020s
. This is because TOPCon offers a clear efficiency jump over PERC with manageable extra cost. HJT is carving out a growing niche: while still a minority technology today (share in the mid-teens of top modules
), it is expected to expand gradually as more factories come online . Tandem cells are on the horizon – they will not dominate in the 2020s, but by 2030 could account for a few percent of high-end installations
Ultimately, a mix of these technologies will coexist. TOPCon’s rapid uptake will push down costs and set a higher baseline efficiency. HJT will serve premium markets and contexts that value maximum yield and stability. Tandems will continue to improve in labs and begin utility-scale use where land is costly. All told, the solar industry is advancing toward module efficiencies well beyond today’s norm, driving solar’s economic competitiveness ever higher .
Sources: Industry reports and manufacturer data (NREL efficiency charts 1 , ITRPV roadmaps ) confirm the trends above. Market studies and press releases current adoption rates, efficiency records, and economic impacts. 19have been used to validate
Best Research-Cell Efficiency Chart | Photovoltaic Research | NREL
https://www.nrel.gov/pv/cell-efficiency
ITRPV: TOPCon to surpass PERC in coming years
https://www.pveurope.eu/solar-modules/itrpv-topcon-surpass-perc-coming-years
What you need to know about PERC solar cells | Aurora Solar
https://aurorasolar.com/blog/what-you-need-to-know-about-perc-solar-cells/
A Roadmap for Photovoltaic Technologies – Lubi Electronics
https://solar.lubielectronics.com/a-roadmap-for-photovoltaic-technologies-the-future-and-challenges/
Perc Solar Cells – Are They The Best Choice?
https://www.solarreviews.com/blog/are-perc-solar-cells-the-best-choice
PERC Technology’s Declining Share In TOP SOLAR MODULES Listing
https://taiyangnews.info/technology/perc-technologys-declining-share-in-top-solar-modules-listing
Why TOPCon will Keep Domination in Future Five Years? – pv magazine International
https://www.pv-magazine.com/press-releases/why-topcon-will-keep-domination-in-future-five-years/
Next-Gen Solar Cell Technologies & Projections
https://taiyangnews.info/technology/next-gen-solar-cell-technologies-projections
HJT Technology Trends In TOP SOLAR MODULES Analysis 2024
https://taiyangnews.info/technology/hjt-technology-trends-in-top-solar-modules-analysis-2024
REC launches HJT modules with 22.5% conversion efficiency
https://www.pv-tech.org/rec-group-module-series-hjt-cells-22-5-conversion-efficiency/
Highest Perovskite Solar Cell Efficiencies (2025 Update) — Fluxim
https://www.fluxim.com/research-blogs/perovskite-silicon-tandem-pv-record-updates
Longi achieves 34.6% efficiency for two-terminal tandem perovskite solar cell prototype – pv magazine International
https://www.pv-magazine.com/2024/09/12/longi-achieves-34-6-efficiency-for-two-terminal-tandem-perovskite-solar-cell- prototype/
Oxford PV starts commercial distribution of perovskite solar modules – pv magazine International
Qcells Achieves World Record Efficiency for Commercially Scalable Perovskite-Silicon Tandem Solar Cell –
Qcells North America
https://us.qcells.com/blog/qcells-tandem-cell-world-record-efficiency/
34.85%! LONGi Breaks World Record for Crystalline Silicon-Perovskite Tandem Solar Cell Efficiency Again
-LONGi
https://www.longi.com/en/news/silicon-perovskite-tandem-solar-cells-new-world-efficiency/