Sizing tool
Solar Street Light Calculator: Battery, Panel & Configuration Sizing
Estimate the LiFePO4 battery capacity, photovoltaic panel power and matching Mast Lighting configuration for a solar street light from four inputs: LED load, nightly runtime, autonomy days and local peak sun hours. The formulas are shown in full below the tool — nothing is hidden behind a lead form.
Inputs
Enter your project parameters
Results assume 85% system efficiency and a 1.25 recharge margin on the photovoltaic module. They are an engineering estimate for shortlisting, not a substitute for the free Dialux lighting design that confirms illuminance and uniformity for your actual road.
Estimated requirement
- Nightly energy demand
- 1,000 Wh
- Battery capacity
- 245 Ah
- Battery energy
- 5,880 Wh
- Solar panel power
- 327 W
- Suggested Mast Lighting configuration
- Split solar street light, 100W LED, 24V LiFePO4, 8m–10m galvanized pole.
Methodology
How solar street light sizing works
Sizing a solar street light comes down to five variables: the nightly load, the autonomy period, local sunlight, the battery chemistry and system losses. Every step below is arithmetic — the reason two suppliers quote very different battery capacities for the same lamp is almost always a different assumption about autonomy or depth of discharge, not a different technology.
| Variable | Formula | Worked example |
|---|---|---|
| Nightly energy demand | LED wattage × operating hours | 100W × 10h = 1,000 Wh per night |
| Energy over the autonomy period | Nightly Wh × autonomy days | 1,000 Wh × 4 days = 4,000 Wh |
| Battery capacity (Wh) | Autonomy Wh ÷ (depth of discharge × system efficiency) | 4,000 ÷ (0.8 × 0.85) ≈ 5,880 Wh |
| Battery capacity (Ah) | Battery Wh ÷ system voltage | 5,880 ÷ 24V ≈ 245 Ah |
| Solar panel power | (Nightly Wh ÷ peak sun hours ÷ charge efficiency) × recharge margin | (1,000 ÷ 4.5 ÷ 0.85) × 1.25 ≈ 327 W |
The worked example describes a 100W luminaire running ten hours a night with four days of rainy-day autonomy at 4.5 peak sun hours — a common configuration for an off-grid road. Change the autonomy to seven days and the battery grows by roughly three quarters, which is why the autonomy assumption deserves more scrutiny than the LED wattage.
Input reference
Understanding each parameter
| LED wattage50W – 300W | Set by road width, mounting height and target lighting class |
|---|---|
| Nightly runtime5–6 h full output, or 6–15 h with dimming | PIR and time-based dimming extend autonomy substantially |
| Autonomy (rainy days)3 – 7 days standard | Higher capacity available for monsoon and long overcast seasons |
| System voltage12V or 24V DC | 24V is usual above roughly 100W of LED load |
| Battery chemistryLiFePO4 | Typical 5–8 year service life, −40°C to 65°C operation |
| Depth of discharge80% assumed | LiFePO4 tolerates deeper discharge than lead-acid |
| System efficiency85% assumed | Controller, wiring and conversion losses |
Regional guidance
Peak sun hours and autonomy by climate
Correct sizing depends on the project's geographic peak sun hours and on how long the wet season keeps the panel in shade. Detailed guidance for each priority destination is on the export markets page.
| Climate zone | Peak sun hours | Suggested autonomy |
|---|---|---|
| Equatorial Africa / South-East Asia (wet season) | 3.5 – 4.5 | 5 – 7 days |
| Sahel, Middle East, arid highlands | 5.5 – 6.5 | 3 – 4 days |
| Coastal South America, temperate zones | 4.0 – 5.0 | 4 – 5 days |
| Monsoon coastal Asia | 3.5 – 4.5 | 5 – 7 days |
Beyond the estimate
The calculator sizes the power system. Dialux proves the light.
A correctly sized battery guarantees the lamp stays on. It does not guarantee the road is lit to the required class. Mast Lighting provides a free professional Dialux simulation based on road width, pole height, installation spacing and the applicable local standard, reporting average illuminance, uniformity and glare for the exact layout you propose. Both services are free, and both come from the same engineering team that builds the product.
Who built this tool
An integrated manufacturer, not a reseller
Mast Lighting manufactures the luminaire, the LiFePO4 battery, the photovoltaic module and the pole in one factory in Yangzhou, Jiangsu, holds independent import and export rights, and is a TÜV Rheinland audited supplier (MIC-ASI264744) operating ISO9001 quality management.
Configurations supported
All-in-one and split solar street lights 50W–300W, LED road lamps 120W–320W, high masts 20m–60m and poles 6m–12m.
Customization
Battery capacity, panel power, LED wattage, runtime profile, pole design and controls — see OEM/ODM customization.
Environment
IP65/IP66 protection, −40°C to 65°C operation, poles engineered to withstand Grade 12 typhoon wind.
Warranty
Three-year warranty on solar street lights, with LiFePO4 cells rated for a typical 5–8 year service life.
Sizing questions
Calculation FAQ
How do I calculate the battery capacity for a solar street light?
How many watts do I need for a solar street light?
How do I size the solar panel for a street light?
How long do solar street light batteries last?
What is the best height for solar street lights?
How many days of autonomy should I specify?
Have an engineer verify your configuration
Send the calculator result together with the road dimensions and we will confirm the sizing, run a Dialux simulation and return factory-direct pricing.