Detailed defect analysis at cell level

With our latest, high-resolution camera, we can detect even the smallest cracks and defects in the solar cells.

High level of quality assurance

Not only hail, but also incorrect installation leaves its mark! We check your PV system in its installed state for hail damage, manufacturing or mounting defects that are invisible to the eye. In most cases, we can identify the cause based on the damage pattern.

Ground-mounted and rooftop systems

We inspect every accessible PV system in its installed state:

100% inspection of ground-mounted systems with the DaySy Rover

Roofs of detached houses and apartment blocks,

Commercial rooftops,

Samples in large ground-mounted systems,

Inspection upon delivery

We also inspect palletised modules for transport damage on delivery. By performing inspections, we detect even the smallest defects that may only affect the energy yield in years to come.

What is the difference between EL and PL?

Luminescence refers to the emission of photons as a result of the recombination of electrons and holes within a semiconductor material. When energy is supplied to a solar cell, electrons are excited to higher energy levels. As they return to the valence band, the excess energy is emitted as photons. Electroluminescence (EL) excites the photovoltaic module electrically, causing it to emit light in the near-infrared range. Areas that emit less light indicate an increased series resistance. In Photoluminescence (PL), the excitation is caused by light, and darker areas appear as a result of lower shunt resistance. Both methods complement each other perfectly for precise fault diagnostics.

When is a PV inspection using Electro- and Photoluminescence recommended?

A photovoltaic inspection is recommended in the following cases:

• After transport or installation
• During the acceptance testing of new PV systems (quality control)
• When buying or selling a PV system (documentation)
• After extreme weather events (e.g. hail or storms)
• In cases of power loss or decreased performance

Luminescence inspections help identify performance losses early and ensure the long-term quality of the system throughout its lifetime.

What types of defects can be detected with EL/PL inspection?

Using Electroluminescence and Photoluminescence, even the smallest defects become visible — including those that may not yet cause power loss but could lead to degradation under wind or snow load. Typical findings include:

• Microcracks or cell fractures
• Deactivated (inactive) cell areas with high series resistance
• Short-circuited cell areas with low parallel resistance
• Defective busbars or broken contacts
• PID (Potential Induced Degradation)
• Hotspots or inconsistent cell quality
• Impact damage from hail or tools
• Complex damage patterns caused by transport, snow load, or vandalism

This allows for precise characterization and documentation of the technical condition of each PV module.

What advantages do EL & PL measurements offer compared to other inspection methods?

The Electroluminescence and Photoluminescence inspection provides numerous benefits:

• Early localization of even the smallest microcracks
• Detection of defects that remain unnoticed in I-V curve measurements
• Higher precision than thermographic imaging — especially for identifying hail damage
• Detailed documentation of module condition
• Proof for warranty and insurance claims
• Non-invasive and completely non-destructive

These methods are considered the gold standard in PV diagnostics and form an essential part of every professional photovoltaic quality assessment.