The last ten years have seen the photovoltaic industry pushing a simple narrative: it is good to have high efficiency, n-type is better than p-type, and the best module is the one that has the highest efficiency reported. There is some truth in this narrative, but one must keep in mind other structural facts of a major importance. Please see five important corrections.
The efficiency ceiling is closer than the headline suggests. The Shockley-Queisser limit indicates a maximum efficiency of about 33.5% in single-junction crystalline silicon solar cells under blackbody assumptions, but with the consideration of Auger recombination, the achievable efficiency in practice is reduced to about 29.4%. New entities manufacturing silicon cells are now providing products with efficiencies in the mid twenties which means that the prospects for improving quality are less optimistic than they seem. The only way to overcome this limit is tandem architecture, and in cases of perovskite-silicon cells it is already possible to achieve efficiency in excess of 42%, while experimental cells show efficiencies above 35%.
The dominant technology is not the most efficient one. HJT technology has an efficiency of 24.5% to 25.8%, the highest for any mainstream crystalline silicon technology, along with the best temperature coefficient of about −0.24%/°C compared to −0.30%/°C of TOPCon and −0.38%/°C of standard PERC. Nevertheless, TOPCon holds about 65% of new cell production for 2026, and HJT is at around 8% to 11%. The primary reason for this is that TOPCon is compatible with existing production lines while HJT cannot be made with PERC production equipment and has to use PECVD equipment that cannot be used with PERC lines.
Temperature coefficient and bifaciality are site-specific multipliers, not universal virtues. The low temperature coefficient of HJT is advantageous since it allows for significant output for hot climate regions, however, its impressive bifaciality factor of 85%-95% is hardly utilized in residential rooftop installations since dark-colored shingles will restrict the rear gain of the solar module to less than 3%. The bifaciality of TOPCon is 75%-85% which works sufficiently enough for utility-scale ground-mount applications. While bifacial gain achievement by using solar technology combined with lesser degradation rate and near to PERC pricing results in the lowest LCOE in moderate areas.
Cell architecture sets the upper bound; bill of materials determines what you actually get. The 2025 Kiwa PVEL Reliability Scorecard found that 83% of module manufacturers had at least one test failure, up from 66% the prior year. In a field experiment conducted in the arid conditions of Qatar, it was found that several HJT panels lost 6.5%–8.7% efficiency in the course of three years, which was due to delaminated encapsulants, whereas a TOPCon technology panel in the same experiment lost only 0.14%. In this sense, it turns out that a cheap HJT panel with weak encapsulation can degrade faster than a solidly manufactured TOPCon one. Thus, decisions made on procurements based on cell technology alone as the only signal of quality are faced with the reliability risk that cannot be accounted for in the efficiency figures mentioned in the datasheet.
The 2026 policy environment has redefined what "compliant" means. China's October 2026 draft revision of the Photovoltaic Manufacturing Industry Specifications deleted multicrystalline and p-type entries entirely, replacing a uniform threshold with technology-specific efficiency floors: 26.0%–26.6% for new cell lines and 24.0%–24.4% for new module lines, depending on whether the route is TOPCon, HJT, or xBC. The significance is not an immediate shutdown order for p-type assets, but the revocation of their "compliance identity" within the policy resource-allocation system-with downstream effects on credit access, energy entitlements, and state-owned procurement eligibility unfolding gradually. Simultaneously, a mandatory national standard taking effect in January 2027 sets a hard market-access floor. Efficiency is no longer a differentiator at the margin; it is the baseline condition for participation.
Overall, the conclusions drawn from these adjustments lead us to one basic takeaway. The solar power value chain is determined not by the maximal theoretical efficiency of a solar cell but rather by the technology that can match its technical characteristics with the environmental factors and financial limitations of a concrete installation site at any given time. In other words, the process of coming to our conclusions is harder compared to simply reading a product description.
