What are bifacial solar panels?
A bifacial solar panel has solar cells that collect light on both faces, front and back, instead of only the sun-facing side. To let light reach the rear, the panel swaps the usual opaque backsheet for a second sheet of glass or a clear plastic film, so it is often called a glass-on-glass or dual-glass module. The front works like any panel, and the back harvests sunlight that reflects up off the ground, a process driven by how much light a surface bounces back, called its albedo.
The cells inside are almost always the same monocrystalline cells (usually PERC or the newer TOPCon type) used in standard panels, wired so both sides feed the same circuit. For the plain-English version of how a cell turns light into current, see how do solar panels work and our explainer on monocrystalline solar panels. The dual-glass build also tends to be tougher and to degrade a bit slower, which is why many bifacial modules carry 30-year power warranties instead of the usual 25.
How much more power do bifacial panels produce?
In a real installation, bifacial panels produce about 5 to 15 percent more energy than an identical single-sided panel, and the best-case gain over a highly reflective surface is roughly 20 to 30 percent. This extra output is called the bifacial gain, and it is a bonus on top of the front-side rating, not a doubling. A panel labeled 400 watts still makes about 400 watts from the front; the rear adds the percentage on top.
The size of that bonus depends entirely on the setup. Bifacial gain climbs when the ground under the panel is bright (white gravel, concrete, a white roof membrane, or snow all reflect well, while dark asphalt and grass reflect little), when the panel is mounted high off the ground so light can bounce under it, when the tilt is steeper, and when rows are spaced apart so panels do not shade each other's backs. Flatten any of those and the gain shrinks toward zero. To see what a standard panel already delivers before adding a rear-side bonus, our 400 watt solar panel breakdown lays out real daily output.
What is the disadvantage of a bifacial solar panel?
The main disadvantage is that the rear side only pays off in the right conditions, and most homes do not have them. On a flush rooftop mount the back of the panel faces the roof deck a couple of inches away, gets almost no reflected light, and the bifacial gain drops to near nothing. You are then paying a premium for a feature you cannot use. The rear can also be partly shaded by the mounting rails, clamps, and the roof itself, which eats into the bonus even when some light does get back there.
The panels are also heavier and pricier. Two sheets of glass weigh more than glass plus a light backsheet, so a bifacial module can run several pounds heavier, which matters for roof load and for handling. They cost more per watt than a plain monofacial panel, and they often want a taller, more open racking system to earn their keep, which adds to the install. None of this is a dealbreaker for a ground array, but on a typical shingled roof the extra cost buys you very little.
Are bifacial solar panels worth it on a house roof?
For a standard pitched roof with a flush mount, usually no. The rear of each panel faces the roof surface just inches away, so there is no reflective gap for the back side to harvest, and the bifacial gain is effectively lost. A regular high-efficiency monofacial panel costs less and produces about the same on that roof, so it is the smarter buy. If you are weighing panel chemistry rather than sides, our monocrystalline vs polycrystalline comparison covers the choice that actually moves output on a roof.
Bifacial panels earn their premium when the back can see light: a ground mount over light gravel, a solar carport canopy open underneath, an elevated rack, a pergola, a fence, or a flat commercial roof with a white reflective membrane and tilted racking. Those are exactly the setups the utility-scale industry uses, which is why nearly all large solar farms now run bifacial. For a home, the honest rule is simple: pick bifacial if you are building an elevated or ground array over a reflective surface, and skip it for a flush roof.
How much do bifacial solar panels cost?
Bifacial panels carry a modest premium over standard monofacial modules, on the order of a few cents more per watt at the panel level, and the higher-quality glass-on-glass build sometimes narrows that gap on longer warranties. Treat any per-watt figure as an estimate: panel prices move, and the installed cost is dominated by racking, wiring, permits, and labor, not the panel alone. Because bifacial often needs taller, more open racking to work, the mounting can cost more than a flush roof job even when the panels are close in price. Our how much does solar cost guide breaks down where the money actually goes.
One important money note: the 30 percent federal residential solar tax credit (Section 25D) expired for systems placed in service after December 31, 2025, so a homeowner who buys and installs an owned system now should budget the full cost with no federal residential credit. Incentives and rules change, so check current state and utility programs before you count on any number, and read our disclaimer. To size a system for your own bill and location and see the payback picture, run the numbers through the solar panel calculator rather than trusting a rule of thumb.
Bifacial vs monocrystalline: which is better?
This is a bit of a false choice, because most bifacial panels are monocrystalline. Bifacial describes how many sides collect light; monocrystalline describes the cell material. A typical bifacial module is built from mono cells, so the real comparison is bifacial versus monofacial (single-sided), both usually made from the same mono cells.
Framed that way, the answer is about the mounting, not the badge. Over a reflective ground or elevated rack, bifacial wins because the rear adds real output. On a flush roof, single-sided monofacial is the better value because the back side does nothing there. So do not choose a panel just because the label says bifacial; choose it only when your install lets the back side see light. For everything else, a good monofacial mono panel is the right call.
Frequently asked questions
Are bifacial solar panels better?
They are better only when the back side can see reflected light. Over a bright ground or an elevated rack, bifacial panels add about 5 to 15 percent more energy, and up to 20 to 30 percent over a very reflective surface. On a flush roof the rear is blocked, so a cheaper single-sided panel produces about the same and is the smarter buy.
What is the disadvantage of a bifacial solar panel?
The rear side only pays off in the right setup. On a flush rooftop the back faces the roof deck and gains almost nothing, so you pay a premium for a feature you cannot use. Bifacial panels are also heavier because of the second glass sheet, cost more per watt, and often need taller, more open racking to earn the extra output.
What is bifacial in a solar panel?
Bifacial means the panel has solar cells that collect light on both the front and the back. The rear replaces the usual opaque backsheet with glass or a clear film, so it captures sunlight reflecting off the ground. The amount of that bonus depends on how reflective the surface below is, how high the panel is mounted, and its tilt and spacing.
Which is better, monocrystalline or bifacial solar panels?
It is not an either-or choice, because most bifacial panels are made from monocrystalline cells. The real comparison is bifacial (two-sided) versus monofacial (one-sided). Bifacial wins over a reflective ground or an elevated mount; monofacial is the better value on a flush roof where the back side gets no light.
Do bifacial solar panels work on a cloudy day?
Yes, they still work, because the rear captures diffuse and reflected light even when the sky is overcast. The bifacial bonus is smaller on a cloudy day than in bright direct sun over a reflective surface, but the front side keeps producing like any panel, and the back adds whatever reflected light is available.