Short answer: check five numbers against physics. Battery energy is volts × amp-hours, and a LiFePO4 pack weighs roughly 1 kg per 85–120 Wh. A panel cannot deliver more than about 230 W per square metre. LED street lights deliver around 120–180 lumens per watt. The battery must cover a night of the stated LED power. Every claim needs a test report for that exact model.
Inflated specifications are common in solar lighting, and they are the main reason lights bought on price go dark in the first rainy season. You do not need a laboratory to catch most of them.
Key numbers
- In Lighting Global’s 2017 market test of solar products bought in Ethiopia, Kenya, Myanmar, Nigeria and Tanzania, 88 % advertised their performance inaccurately (Quality Matters, 2018).
- The current off-grid standard IEC TS 62257-9-8 allows light output to be at most 15 % below the advertised figure and other numeric ratings at most 10 % below.
- LiFePO4 cells store about 90–120 Wh per kg; finished packs with casing and BMS are lower, around 85 Wh/kg in typical datasheets.
- Most commercial LED street lights deliver about 120–180 lm/W at luminaire level. A claim far above 200 lm/W needs an LM-79 report.
Check 1: battery energy in watt-hours, not “mAh”
Battery energy (Wh) = nominal voltage × capacity (Ah). A LiFePO4 cell is 3.2 V nominal, and a 12.8 V pack has four cells in series. The common trick is to quote capacity at cell voltage: “30,000 mAh” at 3.2 V is only 96 Wh, while 30 Ah at 12.8 V would be 384 Wh. Always ask for the capacity and the voltage it refers to, and convert to Wh.
Weight check: a LiFePO4 pack of 1,000 Wh should weigh roughly 8–12 kg including its case. If the whole all-in-one light weighs less than the battery alone should, the capacity is not real.
Check 2: panel watts against panel area
Panels are rated at 1,000 W/m² of sunlight. Even very good modules convert well under a quarter of that, so a panel cannot be rated much above 230 W per square metre. Measure the cell area (not the frame) and multiply by 0.23 kW/m². A “100 W” panel of 0.3 m² is impossible; it is at most about 70 W.
Check 3: lumens against real LED watts
“300 W solar street light” often means nothing: the LED inside may draw 30 W or less. Ask for the actual LED power and the luminaire lumens from an LM-79 test. At typical efficacies of 120–180 lm/W, 6,000 lumens needs roughly 35–50 W. A light sold as 20,000 lumens with a 40 W LED would need 500 lm/W, which no product achieves. Note that LM-80 reports cover the LED chips, not the finished light.
Check 4: the energy balance
The battery must carry the light through the night at its stated power: LED watts × hours at each dimming level. If the spec sheet says 100 W for 12 hours, that is 1,200 Wh a night, before any rainy-day backup. Compare with the battery from check 1 and the panel from check 2. If the numbers do not balance, the light will either dim heavily without saying so, or go dark. Our sizing guide shows the full method.
Check 5: test reports for that exact model
- Light output: LM-79 report (lumens, watts, efficacy) and an IES file for the same model number.
- Luminaire safety: IEC 60598 test report or CB report.
- Battery: IEC 62133 or IEC 62619 safety report, plus UN38.3 and MSDS, without which the light cannot ship.
- Enclosure: IP and IK test reports.
Check that the model number, the laboratory name and the date on the report match the product you are buying, and that the laboratory is accredited (ISO/IEC 17025).
Worked example: a typical inflated listing
| Claim on the listing | Check | Result |
|---|---|---|
| “300 W” all-in-one light | Ask for actual LED power | LED draws 40 W |
| “30,000 lumens” | 30,000 ÷ 40 W | 750 lm/W: impossible. Realistic: 5,000–7,000 lm |
| “100 W panel”, cells 0.35 m × 0.9 m | 0.315 m² × 230 W/m² | At most about 72 W |
| “50,000 mAh battery” | At 3.2 V cell voltage | 160 Wh |
| “Lights 12 hours, 3 rainy days” | 40 W × 12 h = 480 Wh a night | 160 Wh covers about 4 hours at full power |
This is our own illustration of patterns we see in online listings, not a specific product. The light may still be useful, but only at a fraction of the advertised output, and the tender evaluation should compare it with that.
What to check on delivery
- Weigh a sample battery pack and compare with the stated Wh.
- Measure panel cell area and read the panel label.
- Run a full discharge test on a sample battery at the rated current and record Wh delivered.
- At night, measure illuminance on the road with a lux meter at the installed height and spacing, and compare with the design.
- Keep the samples you approved, so the delivered batch can be compared with them.
FAQ
Why do solar street light listings quote such high wattages?
Because buyers compare by watts. The figure often describes an imagined equivalent or the panel, not the LED. Ask for actual LED power and LM-79 lumens.
How can I tell real battery capacity without a lab?
Convert the claim to watt-hours at the stated voltage, then weigh the pack. LiFePO4 packs store roughly 85–120 Wh per kilogram; far more than that is not credible.
Which test report matters most in a tender?
The ones the tender lists, for the exact model. For performance, LM-79 and the IES file; for safety, IEC 60598 and the battery reports; for shipping, UN38.3.
Is a lower price always a sign of fake specs?
No, but price per real watt-hour of battery and per real lumen is a better comparison than price per light.
How we help
Our spec sheets state actual LED power, battery voltage and watt-hours, panel watts and the dimming profile, so the energy balance can be checked. Send us a competing specification or your tender requirements and we will show you the numbers side by side. See our solar street lights and documents.
Sources: Lighting Global / CLASP, Quality Matters (2018) and summary by the Schatz Energy Research Center; IEC TS 62257-9-8:2025 truth-in-advertising tolerances as described by VeraSol; LiFePO4 energy density from manufacturers’ cell and pack datasheets; LED luminaire efficacy from US DOE SSL program publications and current manufacturers’ data. The worked example is our own illustration. Related: Kenya tender checklist, anti-theft design.