Shop window display: how bright and what it costs

How bright the panel has to be

Two light loads hit a window screen. The first is daylight from behind the glass: lighting references put direct sun on the order of 100,000 lux at the pane and an overcast street around 1,000 lux. The second is the reflection of the street in the glass in front of the panel. The panel has to out-shine both.

The tiers the signage trade plans around:

• Behind glass facing daylight, never direct sun: 800 cd/m² minimum.
• Direct sun on the glass for part of the day: 1500 cd/m².
• Exposed glass in sun nearly all day: 2500 cd/m² and above.

Ask for the sustained full-white figure in cd/m², the number the panel holds all afternoon. A peak figure quoted for short highlights is a different measurement and a dimmer screen.

Some of that brightness can be recovered with geometry. A dark shroud behind the screen, or tilting the panel slightly down so the glass mirrors the dark shop interior instead of the bright street, recovers contrast that would otherwise cost more nits. Anti-glare film on the glass does the same job.

Why a consumer TV fails in a window

Three things kill a TV in glass, in the order they show up:

• It is too dim. Typical TVs specify 250 to 350 cd/m², under half the shaded-window floor. In daylight the panel reads as a dark grey rectangle.
• It retains static images. Months of the same menu layout leave faint ghosts of the price column. Rotate stills every 10 to 30 seconds and rebuild the layout monthly; making content for a USB offline sign covers the tools.
• It overheats. A TV is commonly rated 0 to 40 °C, and the air behind sun-struck glass goes past that on a summer afternoon. Window panels are fan-cooled and rated hotter, typically around 50 °C. Most TVs also hang landscape only, which suits a poster, not a tall menu.

What the quote is made of

Four lines make up a typical installed quote:

• The panel. The brightness tier drives it. Moving from an indoor panel to the shaded-window floor, and from that floor to the sun tier, multiplies the panel cost each time; it never adds a small increment.
• The mount and power run. A floor pole or wall arm, and one outlet brought to the window.
• Installation labor. On a one-screen window job this commonly lands at about half the total. A crew that mounts, wires, configures and tests earns it, but the mounting itself is an afternoon of work for two people with a drill.
• The content platform. Cloud signage charges monthly per screen. A panel with a built-in player that reads a USB stick or card has no monthly line at all; what no-subscription signage really costs works through that arithmetic.

Your options at a glance

Worked example: a café window facing west

A café wants a menu screen behind west-facing glass. Sun sits on the glass from mid-afternoon to close, and customers read the screen from about 15 ft away on the sidewalk.

Brightness. Sun on the glass for hours means the sun tier from the list above, with the ambient sensor so it dims after dark.

Text size. The fast-reading planning figure is 20 ft of viewing distance per inch of capital height: 15 ÷ 20 = 0.75 in, about 19 mm capitals. The 30 ft per inch planning floor would allow 15 ÷ 30 = 0.5 in, but street readers are walking, so use 0.75.

Will it fit the panel. A 31.5 inch 16:9 panel at 1920 × 1080 gives about 27.5 × 15.4 in of viewable area, or roughly 70 pixels per inch. Capitals of 0.75 in are 0.75 × 70 = 52 px. Line spacing at 1.7 × capital height is 1.28 in, about 89 px. The 15.4 in panel height holds 15.4 ÷ 1.28 ≈ 12 lines; with a header and margins, plan 8. Five menu items with prices fit with room to breathe.

Cost shape. The quoted job splits about half panel, half installation. Mounting on a floor pole themselves leaves the café paying for the panel, the bracket and one power run, and card playback removes the monthly platform fee. The saving goes into the sun-tier brightness rating, which is the part that decides whether the sign works at all.

Installing it yourself

The mounting share of the quote is the share you can keep.

• Two people lift a 30-inch-class panel onto a floor pole or a wall arm. Bolt into masonry or structure, never just the window frame.
• One outlet behind the window runs the whole sign. If the job needs a new circuit or a fused spur, that part belongs to a qualified electrician; the rest is drill-and-screw work.
• Set the panel 5 to 10 cm behind the glass and tilt it slightly down, so the glass mirrors the dark shop interior instead of the bright street.
• Take the ambient light sensor option if the panel offers one. A window goes from full sun to streetlight in one evening, and a panel held at full brightness after dark is glaring.
• Check from the sidewalk at the brightest hour of the day, at the farthest reading distance. If it reads then, it is bright enough.

Where our displays fit

Our panel-mount series is counter hardware first: the standard builds run 250 to 400 cd/m², built for the counters and endcaps in small retail displays, below the shaded-window floor listed above. Sunlight-readable is an option across that series and the operating range reaches 60 °C, but we publish no cd/m² figure for the sunlight-readable build: ask for the number with the quote before you put one behind glass. The wider display range includes larger wall models through 75 inches, quoted per project, which is where a 31-inch window screen lands. Every unit plays images and video from microSD or USB with no subscription. These units are not rated for outdoor use, so the window job means mounting indoors, behind the glass. A café sign runs through every opening hour, 10 or 12 hours a day; we publish no duty-cycle rating for these units.

When a window panel is the wrong buy

• The screen sits well inside the shop, out of glass light. An indoor panel is right, and setting signage brightness for the room light is the calculation that matters. A touch kiosk facing store light needs 250 or 500 nits in store, not a window rating.
• The client wants one screen for meetings and the window. That dual-use case is covered in a meeting room screen that doubles as a shop window display.
• The budget cannot reach the shaded-window floor at the wanted size. Buy the smaller bright panel. A window punishes a dim screen instantly, at any diagonal.

What to ask before you buy

• The sustained brightness in cd/m² at full white, in writing, and whether an ambient sensor is available.
• The rated operating temperature. Ratings around 50 °C are typical for window panels; a 40 °C rating is a TV.
• The mount hole pattern, such as a 100 × 100 mm VESA pattern, and whether the warranty covers portrait hanging if the menu runs tall.
• Playback from a USB stick or card with no mandatory platform, and the supported video formats.
• What the warranty covers and for how long, including the backlight and the fans.

The decision for each window

Recommendation: buy brightness first and labor second. If sun lands on the glass for any part of the trading day, fit a 1500 cd/m² panel with fan cooling and an ambient sensor; if the window faces daylight but stays shaded, 800 cd/m²; mount it on a floor pole or wall arm yourselves and run content from a card, which drops the installation half and the monthly fee. Fit a consumer TV only where the window never takes strong sun, and rotate its content so no still sits longer than about 30 seconds.

Per case:

• Shaded window: 800 cd/m² commercial panel, self-mounted.
• Sun-struck glass: the sun-tier fan-cooled panel, self-mounted; keep the electrician only for a new circuit.
• Screen deep inside the shop: an indoor panel at 250 to 400 cd/m².
• Budget below a contractor install: a smaller sun-tier panel mounted yourself, never a larger dim one.

Questions