What an LED panel light actually is
An LED panel is a flat luminaire. The light source is a grid of LEDs along the edge or across the back of the panel, diffused through a sheet of acrylic or polycarbonate so the face glows evenly with no visible hot spots. That even, glare-free face is why panels replaced fluorescent troffers in offices, clinics, schools and kitchens. Instead of a bright tube you can see directly, you get an evenly lit rectangle that behaves more like a piece of the ceiling.
Because the technology is simple, the differences between panels hide in the details: how the light is distributed, how the driver is made, what happens when the panel gets hot, and whether the colour of the light stays the same over years of use.
Edge lit and back lit
Edge lit panels place the LEDs along the inside of the frame and bounce light through the diffuser. They are thin, often under half an inch, and they are the cheapest way to make a flat panel. The trade-off is that the light spreads unevenly on large sizes and the LEDs run hotter because they are packed into a narrow strip.
Back lit panels place LEDs across the whole back surface. They are thicker, heavier, more expensive, and they deliver a more even face and better thermal behaviour, particularly on panels larger than two feet square. For sizes up to about two by two feet, edge lit is usually fine. Above that, back lit is worth the extra cost, because a large edge lit panel often shows a brighter centre and slightly dimmer corners.
Lumens, watts and the number that matters
Watts tell you how much electricity the panel uses. Lumens tell you how much light it produces. Marketing tends to quote whichever number sounds better, and cheap panels often quote a lumen figure measured at the LED chip rather than out of the diffuser, where the real number is lower because the diffuser absorbs some light.
Rough guidance for a typical room:
- General ambient lighting: about 20 lumens per square foot of floor area.
- Task areas such as kitchens and workshops: about 50 to 70 lumens per square foot.
- Fine detail work: 100 lumens per square foot or more, usually from layered lighting rather than a single panel.
The spread between a cheap panel and a good one is usually not the lumens on the box. It is whether the panel still produces most of those lumens after two years of daily use, which is what the lumen maintenance figure describes.
Colour temperature and colour consistency
Panels are sold in warm white around 3000K, neutral around 4000K and cool daylight around 5000K to 6500K. Neutral is the common commercial choice because it looks clean without the blue cast of daylight.
Colour consistency is the part buyers overlook. Light is described by CRI for how faithfully it renders colour and by a tolerance band for how far the actual colour drifts from the nominal temperature. A cheap panel might be nominally 4000K but sit at the edge of a wide tolerance band, so two panels bought at different times look noticeably different side by side on the same ceiling. If you are fitting a run of panels, buy them in one batch and check the tolerance figure, or you will see the mismatch every evening.
Drivers, flicker and dimming
The driver converts mains power to what the LEDs need, and it is the part that most often fails first. A cheap driver runs hot, drifts in output as it warms and can introduce flicker that is invisible on a phone camera but causes eye strain and headaches over a working day.
If you plan to dim, confirm that both the driver and the dimmer are compatible. Many panels are sold as dimmable and then buzz or flicker at low levels with a standard wall dimmer, because the driver expects a specific dimming protocol. Getting this wrong is the single most common complaint about panel installations.
Heat, drivers and where panels fail
LEDs lose efficiency as they get hot and lose life faster as they stay hot. A panel that is well made spreads heat across a metal back plate with a decent surface area. A panel that is well insulated in a tight ceiling void with no airflow will run hotter than its rating assumes, and the failure shows up as colour shift, flicker and eventually dead segments.
In practice this means panel life depends on installation as much as on the product. Do not sandwich a panel under insulation, do not bury the driver in a sealed pocket, and if the panel is rated for a particular ambient temperature, respect it.
Size, layout and light distribution
Panels are most commonly 1 by 4 feet, 2 by 2 feet and 2 by 4 feet. The size should follow the grid of the ceiling and the shape of the room. A long narrow room suits 1 by 4 panels aligned with its length. A square room suits 2 by 2 units in a symmetrical grid.
Spacing matters more than raw output. Panels wash light downwards and sideways, so placing them too close to a wall produces a bright band on the wall and a dim far corner. As a starting point, aim for even spacing across the ceiling and keep panels at least a panel-width away from walls.
What to check before buying
- Back lit construction for panels larger than two feet square.
- Lumen output quoted out of the fixture, not at the chip.
- Narrow colour tolerance, and buy a matched batch for a run.
- Driver quality and flicker behaviour.
- Confirmed dimmer compatibility if you intend to dim.
- Metal back plate with real surface area for heat.
- Warranty length, and whether the driver is covered separately.
If you would rather compare the panels that hold up over years rather than the cheapest box on the shelf, the review of LED panel light options covers construction, drivers and colour consistency in more detail.
Installation details that decide the result
Panel lights are usually recessed into a suspended ceiling grid or surface mounted on a plasterboard ceiling. In a grid ceiling, the panel simply drops into the tee bars and sits on them, which is quick and reversible. On plasterboard, a recessed panel needs a cut-out and some form of support, and the cut-out must be accurate because the panel face is visible right to its edge.
Leave clearance above the panel. Panels need airflow to carry heat away, and pressing them up against insulation or a solid substrate traps heat and shortens their life. If the ceiling void is insulated for a roof, keep a gap between the panel back and the insulation rather than compressing the insulation over the panel.
Surface mounting is the simpler route for retrofits and for rooms where cutting a ceiling is not practical, and it removes the need for an accurate cut-out. The trade-off is appearance and a slimmer margin for error on spacing, because a surface mounted panel is more visible from the side.
Six common mistakes with panel installations
- Buying panels from different batches for one ceiling, which shows as a visible colour mismatch between adjacent panels.
- Using a standard wall dimmer with a dimmable panel and then wondering why it buzzes at low level.
- Spacing panels evenly by eye rather than against the ceiling grid, which leaves an obvious off-centre row.
- Placing panels hard against walls, which produces bright wall bands and dark corners.
- Buried drivers that overheat because they were pushed into insulation.
- Judging brightness from the box rather than from the delivered lumens, and ending up with a room that is either dim or clinical.
Layered lighting beats one big panel
A single large panel in the centre of a room lights the middle well and the perimeter badly. Better results usually come from several smaller panels in a grid, plus a separate task light where people actually work. In a kitchen, panels provide the general light and under-cabinet strip lights provide the task light, and that combination is far more comfortable than either alone. Treat the panel as the ambient layer rather than the whole solution, and both the comfort and the appearance improve.
