Technical Analysis
+30% from a shaded cell: what the TÜV test says about AIKO
📅 July 2026
⏱ Reading time: 6 minutes
PVclick Strategy Team
Operational and commercial analysis for the Italian PV sector
What you will find in this article
- You will understand why a single shaded cell penalizes the entire string, not just the covered panel.
- You will see what the TÜV Partial Shading test measures and certifies, and what Class A means.
- You will compare the performance of the AIKO ABC module under shading with that of a standard module, using verifiable data.
- You will know which roofs to propose it for in order to close the sale and avoid a post-installation call.
Why a shaded cell costs you more than you think
In a traditional module, the cells are connected in series: the current flowing through the string is limited by the lowest-performing cell. It takes only a small obstruction—a chimney casting a shadow at 9 a.m., a tree branch, or a skylight railing—to choke the flow across the entire string. The panel doesn’t just lose the output of the shaded section; it loses significantly more than that.
Traditional bypass diodes limit the damage by bypassing entire blocks of cells, but in doing so, they also shut down cells that are fully illuminated. For your client, the result is a system that underperforms relative to projections whenever the sun is low. And when they notice, they call you. It’s the classic job that comes back to haunt you months after handover.
What does the TÜV Partial Shading test measure?
📊 The figure that changes the quote for a shaded roof
- TÜV Rheinland Class A: the highest level of partial shading management, standard 2 PfG 2926.
- Up to +30% more energy from a module with a shaded cell compared to an equivalent standard module, according to AIKO tests.
- The only manufacturer with this certification for mass-market modules: a selling point that competitors lack.
Why back-contact handles shading better
1. ABC Architecture: the darkened cell does not throttle the others.
In AIKO’s ABC (All Back Contact) cell, all contacts are located on the rear, and the interconnection architecture is designed so that a shaded cell has a far less detrimental impact on the rest of the module. While a traditional module shuts down entire blocks via bypass diodes, the ABC module continues to harvest energy from the illuminated cells. In a real-world string, this difference accumulates hour by hour—morning and evening—throughout the system’s entire lifespan.
2. The +30% is not a spike; it is recovered yield.
According to AIKO’s shading performance tests, the advantage under partial shading conditions increases with the extent of the shade: it ranges from a modest margin in light shade to approximately 30% more energy—compared to a standard module—when a cell is completely obscured. In practical terms: for roofs where shading is the norm rather than the exception, this translates to actual production figures that your customer sees on the meter—and that you won’t have to justify during the first inspection.
3. Fewer post-installation calls
A system that handles shade well is one that performs according to plan even in January, when the sun is low and shadows are long. This is the season when calls come in from customers worried they made a bad purchase. With a Class A certified module, you can demonstrate—using hard data—that the system is doing exactly what it was supposed to do; the post-sales discussion is resolved before it even begins.
4. The complex roof ceases to be a design problem.
Many residential roofs are ruled out or undersized because a portion is shaded for a few hours a day. With a module capable of handling partial shading, those roof sections become viable again—meaning more installable surface area, a larger system, and a more lucrative project. What was once a design constraint caused by shade transforms into an area you can monetize.
How to use it in a quote
TÜV certification is not merely a badge to place at the bottom of a datasheet; it is a powerful sales argument that shifts the dynamic of the negotiation. When a client has a roof affected by shading, the conversation often turns defensive—raising concerns like, “Will it produce less than expected?” With a Class A module, you flip the script: by showing them third-party certification of performance under shade, you turn their doubt into a reason to choose you over a competitor offering a standard module.
In the commercial and industrial sectors—where roofs feature skylights, sawtooth roofs, technical equipment, and other obstructions—this argument carries even more weight. Every hour of shading on a string of hundreds of modules represents lost energy; for a self-consumption system, that translates directly into money the client sees saved on their utility bill.
The PVclick response
Two service options:
- Factory Connect: the most competitive price; you handle customs, inland transport, and WEEE compliance.
- All Inclusive: a turnkey solution; we manage customs, transport, WEEE compliance, and final delivery.
The Italian PVclick team oversees product selection, quality control, certification documentation, and technical support in Italian. To learn more about how to assess a module’s true bankability beyond the label, you can find an overview in the guide to Tier 1 panels for distributors and installers.
Conclusion: Three actions to take now
- Bring shaded roofs back into play. Roof sections you previously dismissed due to shading become viable for installation: more surface area means a larger project.
- Leverage TÜV certification in negotiations. “Class A Partial Shading” is a selling point that competitors using standard modules lack.
- Eliminate post-sales risk. A module that performs according to design—even in winter—means avoiding those dreaded complaint calls.
In real-world rooftop installations, shading isn’t the exception; it’s the norm. A module capable of handling this, certified by a third party, isn’t just a technical luxury: it is the key to selling larger systems, closing tough deals, and avoiding the need to explain performance issues once the season is underway.
Do you have a client with a shaded roof that needs to be closed?
Contact the PVclick Italian team for a quote on TÜV-certified AIKO ABC modules via direct import, tailored to your project and delivery schedule.
