Bifacial solar panels are becoming more common across the UK. They are popular for ground-mounted arrays, carports, pergolas, agricultural sites and commercial installations. Unlike conventional panels, they can generate electricity from both the front and the rear surface. At Solar Cleaning South West, one question we are increasingly asked by property owners from Bristol to Cheltenham is simple: if both sides produce power, do both sides need cleaning?
The short answer is that it depends on how and where the panels are installed. Understanding how bifacial panels work makes it much easier to plan the right maintenance.
How Bifacial Panels Work
A standard monofacial panel has solar cells facing the sky and an opaque backsheet underneath. A bifacial panel uses cells that can absorb light on both faces. It is usually encased in glass on both sides, or uses a transparent backsheet.
The front still does most of the work, capturing direct sunlight. The rear side picks up reflected and scattered light bouncing off the ground or surfaces below. Engineers call this reflected light “albedo”. Pale gravel, concrete, light-coloured roofing membranes and even snow reflect far more light than dark grass or soil.
How much extra energy the rear produces depends heavily on the installation. It varies with mounting height, the gap between rows, the reflectivity of the ground and how much the frame shades the rear. In favourable conditions, rear-side gain can be a meaningful addition to total output.
Front Side vs Rear Side: How Dirt Builds Up
The two faces of a bifacial panel get dirty in very different ways.
The Front Side
The front faces the sky, so it collects the same contaminants as any other panel: dust, pollen, bird droppings, leaf litter, moss and lichen. Because the front generates most of the power, keeping it clean remains the priority.
The Rear Side
The rear side is sheltered from direct rain and from most falling debris. As a result it usually stays cleaner. However, it is not immune. It can pick up:
- Dust kicked up from gravel, tracks or farm yards
- Cobwebs and insect activity in the sheltered space beneath
- Splashback of soil and grass cuttings on low ground mounts
- Droppings from birds perching or nesting under the frame
- A light film from damp air and airborne pollution
| Factor | Front Side | Rear Side |
|---|---|---|
| Share of energy output | Majority | Supplementary |
| Exposure to rain | High | Low |
| Typical dirt build-up | Faster, heavier | Slower, lighter |
| Main contaminants | Droppings, pollen, moss, dust | Dust, cobwebs, splashback |
| Recommended cleaning | Regular | Inspect and clean as needed |
So, Do Both Sides Need Cleaning?
For most bifacial systems, the front should be cleaned on a regular schedule. The rear should be inspected at the same time and cleaned whenever it shows visible contamination.
When Rear Cleaning Matters Most
Rear-side cleaning brings the greatest benefit where the installation is designed to capture reflected light. Examples include ground-mounted arrays on pale gravel, elevated commercial frames, solar carports and pergolas. In these settings a dusty or cobwebbed rear surface can quietly reduce the extra gain that justified choosing bifacial panels.
For more on maintaining raised and ground-level systems, see our Ground-Mounted Solar Panels: Complete Cleaning & Maintenance Guide.
When Rear Cleaning Matters Less
Where bifacial panels are mounted close to a roof surface, very little reflected light reaches the rear. The panel then behaves much like a standard one, and rear cleaning offers little practical benefit. On these installations the focus stays almost entirely on the front glass.
How We Clean Bifacial Panels
Bifacial panels need the same gentle approach as any other system, with some extra care for the rear face:
- Assessment: We look at the mounting height, ground surface and access to the rear of the array.
- Front clean: Soft-bristle brushes and purified water remove dirt and droppings without scratching the glass or damaging the anti-reflective coating.
- Rear inspection: We check the underside for dust, cobwebs, nesting and splashback.
- Rear clean where needed: We use a careful brush-and-rinse method, taking care around cabling and junction boxes, which on many panels sit on the rear.
- Final check: We look for any damage, loose wiring or debris trapped beneath the frames.
We never use pressure washers, harsh detergents or abrasive pads. Glass-glass panels are robust, but their edge seals and electrical connections still need to be treated with care.
Do Not Forget the Ground Beneath
Because bifacial panels depend on reflected light, the surface underneath matters too. Overgrown vegetation, algae on concrete, or gravel darkened by moss and dirt all reduce how much light bounces back to the rear cells. Keeping the area under the array tidy and bright helps protect the rear-side gain. It also reduces the splashback that dirties the panels in the first place.
Bird Activity Under Bifacial Arrays
The sheltered space beneath raised bifacial frames can attract nesting birds. Droppings on either face can cause localised shading and, over time, staining. Our article on bird droppings on solar panels explains why prompt removal matters.
Getting Full Value from Your Investment
Bifacial panels are often chosen precisely because they produce more energy than conventional panels in the right setting. Letting either surface become dirty undermines that advantage. Regular front-side cleaning combined with routine rear-side checks keeps both faces working as intended across the life of the system.
Book a Bifacial Solar Panel Clean
Whether you have a bifacial ground mount on a rural property in Gloucestershire or a solar carport at a business in Bristol, Solar Cleaning South West can keep both sides performing well. Get in touch today for a free, no-obligation quote.