Can I distinguish a LiFePO4 from a lead-acid battery without opening the solar light?

Weight is the clearest indicator. A LiFePO4 battery with 300 Wh capacity weighs ~1.8 kg. An equivalent lead-acid battery weighs 5–7 kg. If the complete solar street light unit weighs only 2–3 kg total, the battery is NOT lead-acid (too heavy) and is likely LiFePO4. If the unit is suspiciously heavy (5+ kg for a 30W all-in-one), it may contain a lead-acid battery.

I received the lights but they look different from the samples - what should I do?

Reject the lot immediately if the delivered products do not match the approved sample and purchase order specifications. Document differences with photographs. Issue a non-conformance report (NCR) to the supplier. Withhold payment for the non-conforming lot. For government projects: report to the implementing authority. This is why getting specifications in the purchase order and approving a physical sample before mass delivery is critical.

Is it safe to buy solar street lights from exhibitions and trade shows?

Trade show samples are often premium units specifically prepared for display - the mass production may differ. Always request a production sample (not the exhibition unit) for functional testing, and get all technical documentation before placing an order. A factory visit after the exhibition is the best next step for large orders.

How to Check Solar Street Light Quality Before Buying - Buyer's Guide

Physical Inspection Checklist

Housing material: knock on the fixture body. Aluminium makes a clear ring; plastic makes a dull thud. Weight: a 30W quality solar street light complete unit weighs 3.5–5 kg. Under 2 kg for the same size = plastic or thin sheet metal housing. Gasket: look for a continuous silicone or EPDM rubber gasket between cover and body - this is what creates the IP65 seal. If you see foam, thin rubber tape, or no gasket at all: reject. LED chip appearance: open the fixture if possible. Quality chips (Cree, Osram, Bridgelux) are uniform white in colour, evenly spaced, with no visible yellowing. Panel glass: should be clear, smooth, and rigid - not yellowed or flexible. Tapping the glass: tempered glass sounds solid; thin plastic 'glass' sounds hollow.

Battery Verification

Demand a battery specification sheet - not the full system datasheet, specifically the battery cell specification. The sheet must state: cell chemistry (LiFePO4 - reject if it says Li-ion, NCM, or does not specify). Capacity in Wh (watt-hours) - not just Ah. Minimum acceptable: 30W system = 300 Wh battery, 40W system = 400 Wh battery. Cell brand or origin. Operating temperature range: must include +55°C minimum for Indian summer. BMS (Battery Management System): ask specifically - 'Does this battery have an integrated BMS?' The answer must be yes. If the supplier cannot or will not provide this sheet, the battery specification is being concealed - almost always because it is substandard.

Functional Testing Before Bulk Purchase

For any order above 20 units: request 2–3 sample units for functional testing before placing the full order. Test procedure: fully charge the battery (leave in direct sunlight for 3–4 sunny days). Bring indoors at night. Cover the panel with black cloth - the light should turn on automatically within 30 seconds. Measure lux output with a lux meter at 2m distance. Should match the manufacturer's claimed lux output. Run for one full night - verify it stays on at stated brightness until automatic shutdown at dawn. Repeat the next night. After 2 nights without recharging: verify the light still turns on (tests battery backup). A light that fails any of these tests is not worth buying at any price.

Documentation to Demand

Before placing any order: BIS licence certificate for the specific model (verify on manakonline.in). ISO 9001:2015 certificate (verify issuing body is NABCB accredited). NABL or ERDA photometric test report for the model in your order (not a different model). Battery specification sheet (see above). Warranty letter on manufacturer's letterhead, in your name, specifying 2 years comprehensive coverage. For government orders: also demand ERDA test report, state PWD approval letter, and GeM seller registration proof. Missing any of these is a major red flag - a legitimate quality manufacturer has all of these ready.