Solar Street Light and Municipal Battery Guide

The Harshest Duty Cycle in Small Storage

A solar street light battery works the hardest schedule in small storage: it discharges every night of the year, often deeply, outdoors, at temperatures from summer highs to winter lows, on a pole where a service visit needs a bucket truck. Solar street light projects fail far more often through battery undersizing and charge misconfiguration than through the LED itself. Municipal buyers and luminaire makers who specify the battery as carefully as the lamp avoid the graveyard of dim, dead installations that gave the category a bad name in its early years.

Sizing From the Lighting Load

The arithmetic starts from the luminaire and the lighting profile. An illustrative case: a 40 W LED fixture running an 11-hour night with a dimming profile that averages half power consumes roughly 220 Wh per night. Design practice adds margin for cloudy stretches, commonly enough stored energy for two to three nights without meaningful sun. On the YueQi 12.8V series, a 100 Ah pack holds about 1.28 kWh nominal, which covers the illustrative night several times over and carries the reserve; the 150 Ah and 200 Ah sizes fit brighter fixtures or longer autonomy. The final sizing belongs to the lighting designer, and the pack's tested discharge ratings should be confirmed in writing against the profile.

The Battery Inside the System

• An MPPT controller set to the lithium charge voltage and current of the model harvests the most from a small panel; PWM controllers waste the difference at this scale
• The load output needs a low-voltage disconnect set above the BMS cut-off, so deep protection stays with the BMS and the disconnect is a first line
• A dimming schedule is the cheapest autonomy there is: trimming late-night power extends cloudy-day endurance more effectively than adding battery
• Cable runs on a pole are short, which keeps voltage drop trivial if the cross-section is chosen for the fixture current

Environment and Mounting

The battery box lives with rain, dust, sun and sometimes vandalism. The enclosure needs an ingress protection appropriate to its mounting position, shading from direct sun, and fasteners that resist the tools of thieves as well as the weather. Replaceability matters at the fleet level: a battery that a crew can swap in minutes turns a ten-year service life into a schedule rather than an emergency. Where the luminaire housing integrates the battery, the replacement question should be answered in the design review, not in year six.

What Municipal Tenders Should Ask For

1. A datasheet for the exact battery model, with the test condition behind the cycle-life figure
2. The BMS protection list with threshold values, in writing
3. Certificate copies for the marks claimed, matching the model number
4. The tested charge and discharge temperature ranges for the installation climate
5. A spare parts and replacement plan for the fleet, with pack availability across the project life
6. A pilot installation over one full season before a city-wide roll-out

The pilot is where the specification meets the weather. A season of recorded state-of-charge behavior through winter is worth more than any table in the tender file.

Common Failure Modes and How Design Avoids Them

The recurring failures are an undersized bank that cycles to the BMS floor nightly, a controller profile written for lead-acid that holds the pack too high, water ingress at a cable gland, and theft of accessible hardware. Each has a design answer: sizing with reserve, a lithium profile confirmed with the supplier, glands and strain relief inspected at commissioning, and enclosure hardware chosen for the location. None of them is expensive at design time; all of them are expensive as a service campaign. A commissioning sheet that records the controller settings and the battery serial numbers makes each later service visit a comparison, not an investigation.

Where YueQi Fits

YueQi New Energy, based in Zhongshan, Guangdong, builds 12.8V LiFePO4 packs in 100, 150 and 200 amp-hour ratings, alongside 25.6V classes for larger fixtures and monitoring loads. The catalog lists specifications per model, with CE and UN 38.3 marks shown on the literature and certificate copies available on request. Cycle-life test conditions, temperature ranges for a specific model and commercial terms are to be confirmed in writing, so the tender file rests on documents the supplier stands behind.