Writing Winning Solar Street Light Tender Specifications: A Contractor's Guide

Every contractor who has bid on a municipal solar street light project has seen the same pattern. The lowest bidder wins the contract, installs the lights, and within 18 to 24 months a third of the units are dark. The battery has degraded, the panel has delaminated, or the ABS housing has cracked under UV exposure. The municipality then faces a costly replacement cycle, and the contractor's reputation suffers alongside the failed product. The root cause is almost always a tender document that specified wattage instead of lumens, said nothing about battery cycle life, and allowed ABS housing when aluminum was required. This guide explains how to write a solar street light tender specification that attracts qualified products and disqualifies the low-quality bids that fail within two years.

Specify Lumens, Not Watts

The single most important change a tender writer can make is to replace wattage requirements with minimum luminous output in lumens. A 200W label tells the buyer nothing about delivered light because LED efficiency varies from 100 to 180 lumens per watt depending on chip quality and driver design. A lumens requirement forces bidders to prove actual performance. The CMJ Solar MJ-SSO100 produces 4500 lumens from 45 pieces of 5050 LED chips. The MJ-SSO200 produces 6500 lumens from 90 pieces. The MJ-SSO300 reaches 8500 lumens from 135 pieces, and the flagship MJ-SSO400 delivers 12000 lumens from 180 pieces. For the split-type Interstellar II series, the MJ-XJ902 200W delivers 1800 lumens, the MJ-XJ903 300W delivers 2650 lumens, and the MJ-XJ904 400W delivers 3358 lumens. These measured outputs allow a municipality to verify compliance against the tender data sheet.

Set IP65 Minimum and Require LiFePO4 with Stated Cycle Life

Every outdoor solar street light must carry at minimum an IP65 rating. The first digit, 6, means complete protection against dust, and the second digit, 5, means protection against water jets from any direction, covering rain, wind-driven spray, and pressure washing. IP65 is not a premium feature; it is the baseline for any fixture installed outdoors. Both the SSO and Interstellar II series carry IP65 ratings. Tender documents should state IP65 as a non-negotiable requirement and require the bidder to submit test reports from an accredited laboratory.

Battery chemistry is the second most critical specification. Tender documents should require lithium iron phosphate (LiFePO4) batteries and state a minimum cycle life at 80 percent depth of discharge. The SSO200, SSO300, and SSO400 use Grade A LiFePO4 cells rated for <strong>4000 cycles</strong>. The SSO100 is rated for 2000 cycles, and the Interstellar II XJ902 through XJ904 use Grade A LiFePO4 cells rated for 2000 cycles. A 4000-cycle battery, at one cycle per day, lasts nearly 11 years before reaching 80 percent capacity. A 2000-cycle battery lasts roughly 5.5 years. Tender writers should match the cycle life requirement to the expected service life of the project and weight the scoring accordingly.

Require Grade A Monocrystalline Panels and Define Battery Capacity

Solar panel quality varies dramatically. Tender documents should require Grade A monocrystalline silicon panels and state the panel wattage. Polycrystalline panels or Grade B monocrystalline cells degrade faster, produce less power per square meter, and are more prone to hot spots and delamination. The SSO series uses Grade A monocrystalline panels from 4V/60W on the SSO100 up to 4V/110W on the SSO400, with panel dimensions from 860 by 350mm to 1600 by 350mm. The Interstellar II uses 5V panels from 30W to 45W. The tender should state that panel wattage must be sufficient to recharge the battery within the stated charge time and should require the bidder to provide panel efficiency data.

Battery capacity must also be specified because it directly determines autonomy. The SSO100 uses a 60Ah pack, the SSO200 uses 85Ah, the SSO300 uses 105Ah, and the SSO400 uses 170Ah. These capacities support the 4 to 5 rainy day autonomy that the SSO series delivers. The XJ902 uses a 20Ah prismatic pack for 18 hours of discharge, the XJ903 uses 30Ah for 18 hours, and the XJ904 uses 36Ah for 2 rainy days. A bidder who claims 5 rainy days of autonomy with a 20Ah battery should be disqualified on the arithmetic alone.

Define Pole Diameter, Installation Height, and Radar Sensing

An all-in-one solar street light must fit the pole it is mounted on. The SSO series is designed for a <strong>76mm pole diameter</strong>, which is an international standard for street light poles. Tender documents should state the pole diameter and require the light housing to include an adapter that fits without modification. The Interstellar II XJ series ships with an arm bracket for wall or pole mounting, giving contractors more flexibility on pole types. Installation height should be specified based on road width and required illuminance. The SSO100 is rated for 6m, the SSO200 for 6 to 8m, the SSO300 for 8 to 10m, and the SSO400 for 10 to 12m. These heights correspond to the lumen output and beam angle of each model, and specifying the correct height prevents the common error of mounting a low-output light too high.

Modern solar street lights should include a radar sensor that dims the light when no movement is detected and brightens to full output when a pedestrian or vehicle approaches. This extends battery life and reduces light pollution. The SSO series offers smart light control, remote control, and radar sensor as standard. The Navigator II series offers three selectable modes: steady-on, 2 or 3 hours steady then radar mode, and full radar mode. Tender documents should require at minimum a radar-based motion sensor with adjustable detection distance, typically 6 to 8 meters. Passive infrared sensors are less reliable outdoors because they are affected by ambient temperature and should not be accepted as an equivalent.

Specify Housing Material: AL6063 vs ABS

Housing material determines both heat dissipation and structural longevity. The SSO premium series uses <strong>AL6063 aluminum alloy with Teijin PC</strong> lens covers. AL6063 is a structural aluminum grade with excellent thermal conductivity, corrosion resistance, and mechanical strength. It acts as a heat sink for the LED array, keeping junction temperatures low and extending LED life. Teijin PC is a high-impact, UV-resistant polycarbonate that resists yellowing and cracking. The Interstellar II XJ series uses die-cast aluminum housing, which also provides good heat dissipation and durability. ABS plastic housings, common on the cheapest imported units, become brittle after 12 to 18 months of UV exposure and do not dissipate heat effectively, leading to accelerated LED and driver failure. Tender documents for main roads should require aluminum housing with PC lens. ABS may be acceptable for low-traffic residential pathways where replacement is easy, but it should never be specified for arterial roads or extreme climates.

Set Rainy Day Autonomy and Score Beyond Price

Rainy day autonomy is the number of consecutive days the light can operate at its programmed output without a full solar recharge. The SSO series is rated for 4 to 5 rainy days, the Navigator II for 3 rainy days, and the XJ904 for 2 rainy days, while the XJ902 and XJ903 offer 18 hours of continuous discharge. The correct requirement depends on local climate. In regions with a defined monsoon season, specify 4 to 5 rainy days and select the SSO series. In regions with consistent year-round sun, 2 to 3 rainy days may be sufficient, making the XJ or Navigator II a more cost-effective choice. Tender writers should obtain local meteorological data rather than using a generic figure.

A tender that awards 100 percent of the score to price will always attract the lowest-quality product. Instead, structure the evaluation with technical criteria carrying 60 to 70 percent and price carrying 30 to 40 percent. Technical criteria should include verified lumen output, battery cycle life, panel grade and wattage, housing material, IP rating, and warranty terms. Require bidders to submit independent test reports for the LED, battery, and panel. Require a minimum warranty of 2 to 3 years for the complete fixture and a separate warranty for the battery. CMJ Solar, manufactured by Guangdong Youzhuo Lighting Photoelectric Technology Co., Ltd., supports its SSO and Interstellar II products with documented specifications and factory-backed warranty terms.

Why the Cheapest Bid Fails and How to Write the Clause

The failure pattern of low-cost solar street lights is predictable. The battery is undersized and uses unbranded cells rated for fewer than 1000 cycles, degrading to 50 percent capacity within 18 months. The panel uses Grade B or C cells with hidden cracks. The ABS housing cracks under UV and thermal cycling, allowing water into the compartment. The LED driver runs hot because there is no aluminum heat sink, accelerating lumen depreciation. Within two years, 20 to 40 percent of the units are dark. A well-written tender prevents this by specifying the components that determine longevity. A strong clause reads as follows: the fixture shall produce a minimum of X lumens verified by independent test report; the battery shall be Grade A LiFePO4 with a minimum of 2000 or 4000 cycles; the panel shall be Grade A monocrystalline at X watts minimum; the housing shall be AL6063 or die-cast aluminum with UV-stabilized PC lens; the fixture shall carry IP65 minimum; autonomy shall be X rainy days minimum; a radar sensor with remote control and multiple modes shall be integrated; the pole adapter shall fit 76mm; and the fixture shall carry a minimum 2-year warranty.

For arterial roads and high-priority municipal projects, specify the SSO premium series with its 4000-cycle batteries, AL6063 housing, and 4500 to 12000 lumen output. For collector roads and industrial park streets, the Interstellar II XJ series with die-cast aluminum housing and 1800 to 3358 lumens provides strong value. For residential streets and pathways, the Navigator II series offers a balance of performance and affordability. Browse the full solar street light range to build a tender specification that matches the project's road classification, climate, and budget.