Spacing is where solar street lighting projects quietly win or lose money. Space the poles too far apart and the road shows dark patches between fixtures; too close and you are buying poles, foundations and luminaires you did not need. This guide gives you the calculator, the formulas behind it and three worked examples for roads and parking lots.
It covers:
✔ A free interactive spacing calculator
✔ The three inputs that decide the layout
✔ Worked examples: residential road, collector road, parking lot
✔ Four layout mistakes to avoid
Try the Spacing Calculator
Enter your site data below – the calculator updates the spacing, lumens and pole count as you type. You can also open it full size on our solar street light spacing calculator page.
The Three Inputs That Decide the Layout
1. Road or area width sets the pole height. As a rule of thumb used across the industry, the mounting height should roughly equal the road width for a single-side arrangement, and can be slightly less when lights are staggered on both sides. A 6 m community road works from a 6 m pole; a 10 m artery needs 9-12 m.
2. Pole height sets the spacing range. Spacing of about 3-4 times the mounting height is the starting point for single-side layouts, and 4-5 times for staggered layouts where every point on the road receives light from two directions. Stretching beyond that range costs uniformity, even when the lux number still looks acceptable on paper.
3. Spacing sets the lumens each lamp must deliver. The further apart the poles, the more ground each fixture must cover:
Required lumens per lamp ≈ (target lux × spacing × road width) ÷ utilization factor
The utilization factor describes how much of the lamp’s light actually lands on the road; 0.25-0.35 is a realistic planning range for typical street light optics. Typical average illuminance targets are around 5-10 lux for residential roads and parking, 10-15 lux for collector roads and 15-20 lux for main roads – always confirm against your tender specification or local standard.
Worked Examples: Roads and Parking Lots
| Scenario | Inputs | Calculator output |
|---|---|---|
| Residential street (Philippines barangay road) | 6 m wide, single side, 6 m poles, 8 lux target, UF 0.30, 500 m road | 18-24 m spacing range; about 2,900-3,200 lm per lamp; 30W class; roughly 28 poles |
| Collector road | 8 m wide, staggered, 7 m poles, 12 lux target, UF 0.30, 1,000 m road | 28-35 m spacing range; about 9,000-11,200 lm per lamp; 100W class; roughly 31 poles per run of two sides |
| Compound parking lot | 25 m wide area, 8 m poles, 10 lux target, UF 0.30, 100 m length | 24-32 m spacing; about 6,700-8,900 lm per lamp; 80W class; 4-5 poles |
Run your own numbers in the calculator above – the outputs update instantly, and the warning box flags layouts where the pole height does not match the road width. For the wattage dimension in more detail, see our guide to choosing solar street light wattage, pole height and spacing.
Four Layout Mistakes to Avoid
- Sizing for sunny days only. In the Philippines, Nigeria and other tropical markets, weeks of overcast weather are normal. Specify battery autonomy for the rainy season, or the layout fails exactly when residents judge the project.
- Stretching spacing to cut the pole count. Fewer poles means more lumens per lamp, a bigger panel and battery – and dark patches between fixtures. Total cost often does not drop; it just moves into bigger hardware.
- Ignoring uniformity. A road can average the target lux and still look bad if light pools under each pole. Keep spacing within the recommended multiple of pole height and prefer staggered layouts on wider roads.
- Quoting by wattage alone. Two 60W fixtures can differ enormously in delivered lumens. Specify delivered lumens, battery chemistry and autonomy in writing when comparing quotations – see our all-in-one vs split comparison for the format dimension.
Frequently Asked Questions
Q: How far apart should 6 meter solar street light poles be?
A: For a single-side layout, 18-24 m is the typical starting range (3-4 times the mounting height); a staggered layout can stretch to 24-30 m. The spacing must be paired with enough lumens per lamp – run the calculator above with your road width and target lux to confirm.
Q: How many solar street lights do I need for 1 km of road?
A: Divide the road length by the design spacing and add one pole: at 20 m spacing, a 1,000 m single-side layout needs about 51 poles; at 25 m spacing, about 41. A staggered layout halves the per-side spacing but adds poles on both sides. The calculator gives the count once you enter the road length.
Q: What lux level should I use for a parking lot?
A: Around 5-10 lux average illuminance is a common planning target for open parking areas, with higher values at entrances and payment points. Confirm the requirement with the site owner or local standard before finalizing the layout.
Conclusion: Calculate First, Buy Second
A solar street light layout is three numbers working together: pole height, spacing and lumens per lamp. Start from the road width, keep the spacing within 3-5 times the pole height depending on the arrangement, and size each fixture for the area it must actually cover – then verify the hardware against delivered lumens, not nameplate wattage.
Want the layout checked before you order? Qichenshop manufactures all-in-one and split solar street lights from 20W to 200W+ for global distributors, contractors and EPC buyers, with an MOQ from 50 units, typical lead time of 15 days and T/T 30% deposit / 70% balance terms. Send your road width, pole height and nightly operating hours via our contact page and our engineers will run a free layout check – or browse the full range in our shop.
