How color changes
Allows determination of faults by looking at the top (light‐receiving surface) of the solar module
Simply affix the temperature label on each solar panel at the time of installation to allow detection of abnormal heat generation caused by continuous electric current passing through bypass diodes when there is a fault with a panel. This makes it easy to identify faulty panels (panels with a potential cluster power generation problem triggered by a circuit break inside the module). Allows determination of faults by looking at the top (light‐receiving surface) of the solar module. A change in the color of the label indicates the solar module has a fault. Temperature history can be checked at any time as color changes are irreversible.
Type of compatible solar panels
- Faults can be detected in solar panels with bypass diodes.
- Bypass diodes are typically found in crystalline silicon (monocrystalline or polycrystalline silicon) solar panels. Some thin‐film silicon panels and CIGS panels are not equipped with bypass diodes.
- Some solar panel manufacturers do not use bypass diodes. Please ask your panel manufacturer in advance if bypass diodes are installed.
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|Product Number||Color Change Temperature（℃）||Period（min）||JAN Code|
How to Identify a Faulty Panel
It is possible that a fault has occurred if the color change of a Thermo Label® on a panel has advanced more than the color change on surrounding panels (up to 80 or 90°C).
Where to Affix Thermo Label®
① Check the location of the bypass diode underneath the solar panel.
② Affix the Thermo Label® to the light‐receiving surface (top of the panel) directly behind the bypass diode.
③ Sunlight will not be blocked if the Thermo Label® is affixed so that the white circles are aligned with the white line between the cells.
* See “4. How to Identify a Faulty Panel.”
* Bypass diodes generate heat also when the panel is shaded for long periods during daylight hours and the color change of the Thermo Label® may advance more than the color change on other panels as a result.
① Faulty panels can be identified with greater accuracy with Thermo Label® 5E‐75 directly affixed to bypass diodes underneath the panels.
② It is possible that a fault has occurred if the color changes in the 80‐95°C range.
How Bypass Diodes Work and Causes of Abnormal Heat Generation
- When shaded from sunlight and therefore not generating electricity, solar panels are simply resistance and consume energy generated by the other panels, reducing the power generation of the entire module.
In panels where a fault has occurred, too, electricity continues to flow from other panels, which may result in thermal damage.
Bypass diodes connected to panels in advance prevent power generation deterioration and protect panels from damage by allowing the current to bypass panels where a fault has occurred.
- As current is continuously diverted through a bypass diode when a break (fault) occurs in an interconnector, which connects the cells, the diode generates an abnormal amount of heat. Thermo Label® changes color as the temperature rises with heat generation, allowing the faulty panel to be identified.
- Abnormal heat generation also occurs when there are panels in areas that are shaded for long periods during daylight hours. But this is not a fault. Using Thermo Label® alone, it is not possible to distinguish between abnormal heat generation due to a fault and abnormal heat generation due to being shaded for long periods during daylight hours. It is therefore necessary to check the site for shaded areas when a panel is found to be generating an abnormal amount of heat.
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