What you will see
- Output close to expectations for a similar front-facing array.
- Marketing claims that do not explain the roof arrangement.
- Rear surfaces heavily obstructed by the structure or nearby equipment.
- A comparison with panels installed over a very different ground surface.
- Monitoring may show total array output without separating front and rear contributions. In that situation, the app alone cannot measure the rear-side gain directly.
Why it happens
Rear-side production depends on the light reaching the back of the module. LONGi identifies surface reflectivity, installation height, row spacing, tilt and rear shading as relevant factors. A layout with limited useful rear illumination may achieve much less additional generation than another site.
Bifaciality and installation-level energy gain are different measures. The first describes relative rear-side performance under specified test conditions; it should not be read as the percentage by which a particular property’s annual generation will increase.
A performance review should therefore examine both the original assumptions and the installed arrangement. It should also account for ordinary causes of reduced system output before attributing everything to the bifacial design.
What the back of the panel sees
Bifaciality is a module measure. The gain on your roof depends on the installation.
What you can check yourself
- Find the exact module model and original proposal.
- Ask whether the estimate included rear-side generation.
- Provide existing installation photographs and layout drawings.
- Note later additions that may obstruct light around the array.
- Save complete production records rather than a single peak reading.
- If the rear of the panels cannot be seen safely, leave that inspection to the solar team.
What not to do
- Do not place improvised mirrors around panels, coat module surfaces or raise the structure without an engineering review. Do not assume painting a roof will deliver a quoted gain without checking the design and roofing implications.
When to call us
- Request a review when actual performance persistently differs from the proposal’s stated assumptions or when changes around the array may have affected rear illumination.
Bifacial arrays in Faisalabad and Lahore
On Faisalabad and Lahore rooftops the surface under the array matters. Send our team the panel model, proposal and layout photos.
Send us
The panel model, proposal, available layout photographs, production history, and your city and area.
Technical references
Reviewed 25 September 2026. Manufacturer documents are cited for general principles; your exact model’s manual always applies.