Efficiency numbers get thrown around constantly in solar cell marketing — 23%, 24.5%, 25%+ — but module manufacturers evaluating suppliers often don’t get a clear explanation of what’s actually driving those numbers, or which figures are realistic for mass production versus lab-only records. Here’s a grounded look at TOPCon efficiency: what creates it, what current benchmarks actually look like, and how to evaluate a supplier’s efficiency claims.

What “Efficiency” Actually Measures

Cell efficiency is the percentage of sunlight energy hitting the cell that gets converted into usable electrical energy. A 24% efficient cell converts 24% of the solar energy reaching its surface into electricity; the rest is lost to reflection, heat, recombination, and resistance within the cell structure.

This single number is the product of multiple underlying factors, and understanding which factor TOPCon actually improves helps explain why the technology delivers consistent gains over PERC.

Three Sources of TOPCon’s Efficiency Advantage

1. Reduced rear-surface recombination. This is TOPCon’s signature contribution. The tunnel oxide and doped polysilicon layer on the cell’s rear surface passivates that surface extremely effectively, meaning fewer electrons and holes recombine before they can be collected as current. This single improvement is responsible for the largest share of TOPCon’s efficiency gain over standard PERC architecture.
2. Improved open-circuit voltage. Reduced recombination doesn’t just save a small amount of lost energy — it directly raises the cell’s open-circuit voltage (the maximum voltage available from the cell), which is one of the two core variables (alongside current) that determine overall power output.
3. N-type bulk material advantages. Independent of the TOPCon passivation layer itself, the underlying n-type silicon wafer has lower bulk recombination and better resistance to common degradation mechanisms (like boron-oxygen light-induced degradation, which affects p-type material) than p-type wafers used in PERC.

Current Industry Benchmarks (2026)

As of early 2026, market analysts at CRU report that leading TOPCon module efficiencies exceed 24.5%, with median module efficiencies across the broader market sitting around 23%. These are module-level figures (accounting for cell spacing, frame losses, and connection losses), which are always somewhat lower than the underlying cell efficiency reported in isolation.

It’s worth distinguishing between three different efficiency claims you’ll encounter from suppliers:

• Lab/record efficiency: Best-case results under controlled testing conditions, often achieved on small-area cells that aren’t representative of mass production
• Mass-production cell efficiency: What’s actually shipping at volume, typically several percentage points below lab records
• Module efficiency: The real-world figure that matters for your installation calculations, always lower than cell efficiency due to module-level losses

A supplier quoting only lab records without mass-production figures is giving you a marketing number, not a sourcing number.

Why the “Last Percentage Point” Matters More Than It Sounds

A jump from 23% to 24% efficiency sounds marginal, but it compounds significantly at scale. For a utility-scale project with a fixed land footprint, a 1 percentage point efficiency gain can translate into meaningfully more total power generated from the same physical installation — which directly affects the project’s levelized cost of electricity (LCOE) calculation. This is part of why module manufacturers competing for utility and commercial contracts pay close attention to cell efficiency specifications when selecting suppliers, even when the percentage differences look small on paper.

Efficiency Is Not the Only Metric That Matters

It’s worth resisting the temptation to chase the highest efficiency number in isolation. A cell’s real-world value to a module manufacturer depends on several factors working together:

• Efficiency (power output per unit area)
• Degradation rate (how much efficiency is retained over 25 years)
• Temperature coefficient (how much efficiency drops in real-world heat)
• Bifacial performance (additional energy capture from rear-side light, where applicable)
• Consistency across production batches (whether the rated efficiency is reliably delivered, not just achieved occasionally)

A supplier with slightly lower peak efficiency but excellent consistency and a strong temperature coefficient can deliver better real-world project performance than a supplier chasing headline efficiency numbers inconsistently.

What to Ask Suppliers About Efficiency Claims

When evaluating cell suppliers, ask for:

1. Mass-production efficiency data, not just lab records
2. Third-party verified test results, where available
3. Batch-to-batch efficiency variance data
4. Temperature coefficient and degradation rate specifications alongside the headline efficiency number

PTECH Solar’s Approach to Efficiency

PTECH Solar manufactures n-type TOPCon cells in the 210R format, with efficiency specifications based on mass-production output rather than isolated lab results. We provide manufacturers with detailed technical documentation covering efficiency, temperature performance, and degradation characteristics as part of the supplier evaluation process.

This article is part of PTECH Solar’s technical resource series for module manufacturers and B2B solar buyers. For technical specifications on our N-type TOPCon 210R cells, visit ptechsolar.com.