مقارنة الألواح الشمسية ثنائية الوجه

In bifacial panels, the cells are embedded between two panes of glass and the rear side lets light through. Light reflected from the ground, a light-coloured wall or gravel generates extra power. How much depends heavily on the surroundings: a bright surface and distance from whatever is behind the panel help, while a dark wall directly behind it adds almost nothing.

Manufacturers often state the extra yield as a “bifaciality factor” or a percentage range. Such figures are maximums under favourable conditions. It's better to plan conservatively and treat the rear-side gain as a bonus.

Not every mounting location makes equally good use of the rear side:

The glass-glass design protects the cells well against moisture and micro-cracks, which is why many manufacturers offer longer product and performance warranties. The downside is weight: a 450 Wp panel can easily weigh over 20 kilograms. Check the load capacity of the mount and only clamp the panel in the areas approved by the manufacturer, so the glass isn't put under stress.

Compare the price per Wp and use the front-side rated output as the basis, not the maximum output advertised including rear-side gain. Check the performance warranty – often 25 to 30 years for glass-glass panels – and the guaranteed residual output at the end. Dimensions, frame height and permitted clamping areas also matter, so the panel fits your mount. For the power that actually reaches the inverter, what counts are the front-side electrical values plus a realistic, rather small extra.