Innovation Signal 68 (2026) | 21 October 2026
Tandem solar cells are becoming better at withstanding damaging shading conditions
Short note, about 5 minutes to read.
What happened
Shading does more than temporarily reduce the electricity produced by a solar cell. Under some conditions, a shaded cell can be forced to operate in reverse (reverse bias), which can damage the cell and reduce its performance.
That problem is becoming more manageable in perovskite-silicon tandem solar cells.
Damaging reverse bias → greater resilience → longer endurance under shading stress
In 2024, researchers from 3Sun and CEA demonstrated tandem cells that could withstand severe reverse-bias conditions, including tests that reproduced partial shading.
More recently, researchers led by City University of Hong Kong strengthened vulnerable parts of the perovskite cell using protective insulating layers (graded dielectric layers). The tandem cells retained more than 92% of their performance after 1,000 hours at −15 volts. A multicell device retained more than 90% after 1,000 hours of shading stress.
Together, the results show that tandem solar cells are becoming better able to withstand an important source of damage from partial shading.
Why this matters
Solar panels cannot avoid every period of partial shading. Trees, buildings, dirt or other obstructions can leave some cells receiving less sunlight than others.
If tandem cells can withstand those conditions without lasting damage, future high-efficiency solar panels could retain more of their performance during everyday use.
Who should care
- Solar-cell and module manufacturers
- Solar-energy companies
- Photovoltaic materials and equipment companies
- Solar project developers and operators
- Energy technology and research organisations
- Investors tracking emerging energy technologies
What could change over the next 2 to 3 years
The next step will be showing that this resilience can be maintained in larger tandem modules and during longer outdoor use.
Watch for larger modules, repeated shading tests and longer outdoor demonstrations showing whether the protection seen in laboratory testing survives under more varied operating conditions.
What might block this
Laboratory stress tests cannot reproduce everything a solar panel will encounter during years of outdoor use.
Heat, moisture, repeated shading and manufacturing defects could still reduce performance. The recent results therefore do not yet show that tandem solar cells can withstand these conditions reliably over a full operating lifetime.
Why I am sharing this
Solar cells do not operate under perfect conditions. As their efficiency increases, protecting that performance from ordinary operating stresses becomes increasingly important.
The next advance in tandem solar may be not just producing more electricity from the same space, but making that advantage harder to lose.
If you found this useful, please consider forwarding it to someone who may also find it valuable.
Archive Tags
Tandem Solar · Perovskite-Silicon · Solar Durability · Partial Shading · Photovoltaics