How to Size Solar Street Lights: LED Power, Battery, Panel, and Spacing Guide

Correctly sizing solar street lights ensures adequate illumination, reliable overnight operation, and years of maintenance-free service. Undersized lights leave dark spots; oversized lights waste money. This guide covers every sizing parameter.

Step 1: Determine Required Illumination

Step 2: Size the Battery

Battery capacity = LED watts x operating hours x autonomy nights / DoD / efficiency

Example: 60W LED, 10 hours/night, 3 nights autonomy, 80% DoD (LiFePO4), 90% efficiency:

60 x 10 x 3 / 0.80 / 0.90 = 2,500 Wh = 2.5 kWh battery

At 12.8V LiFePO4: 2,500 / 12.8 = 195 Ah

Step 3: Size the Solar Panel

Panel watts = Daily LED consumption / Peak sun hours / charge efficiency x safety margin

Example: 600 Wh/night, 6 PSH (UAE), 90% efficiency, 1.3 safety margin:

600 / 6 / 0.90 x 1.3 = 144W solar panel

Step 4: Choose the Right Light Type

All-in-One

Panel, battery, LED, and controller in a single unit. Best for residential streets and pathways. Felicity Solar all-in-one range: 30W to 200W.

Split Type

Panel mounted separately from the LED head. Best for high-power applications (100W+) that need larger panels than can fit on top of the light head.

Step 5: Configure Dimming Schedule

Intelligent dimming extends battery life and reduces costs:

With this schedule, the 60W light uses only 420 Wh per night instead of 600 Wh — a 30% reduction that allows a smaller battery and panel.

Pole Spacing Formula

For uniform illumination: Spacing = Pole height x 3 to 4

A 7m pole: spacing = 7 x 3.5 = approximately 25m. Adjust for road width — wider roads need closer spacing or lights on both sides.