Most bad solar lighting purchases are not caused by dishonest suppliers. They are caused by reasonable assumptions that happen to be wrong. These five appear in almost every project review.
Myth 1: A Bigger Panel Always Means More Power
Panel wattage is a peak figure measured under standard test conditions. A large panel mounted flat, partly shaded or permanently dusty may harvest less than a smaller, well-angled one. Orientation, tilt and cleaning matter as much as size.
Check instead: the mounting angle relative to latitude, and the realistic harvest after dust and heat derating.
Myth 2: A Higher IP Number Means It Will Not Leak
IP ratings describe a test, not a service life. Water usually enters through cable glands and battery covers, not the lens. A single gasket around a complex housing can pass a laboratory test and still leak in the field.
Check instead: the number of gaskets, the gland type and whether condensate has a path away from the PCB.
Myth 3: More Wattage Means a Brighter Road
Illuminance on the road depends on distribution, pole height and spacing as much as power. Doubling wattage on the same spacing creates bright pools and dark gaps. Tightening spacing usually produces more even light for less money.
Check instead: a layout drawing with spacing and beam type, not a wattage claim.
Myth 4: Battery Capacity Tells You the Runtime
Amp-hours at 25°C do not describe a cold night or a hot summer. Usable capacity depends on chemistry, temperature, depth of discharge and controller behaviour.
Check instead: runtime at realistic temperature, with the dimming profile stated.
| Myth |
Better question |
| Bigger panel is better |
What is the harvest after tilt and dust? |
| Higher IP means no leaks |
How many gaskets, and how are cables sealed? |
| More watts is brighter |
What spacing and beam does the layout use? |
| Ah equals runtime |
What runtime at 45°C with dimming? |
| Warranty means covered |
Which parts, and who pays freight? |
Myth 5: A Long Warranty Means Low Risk
A warranty that excludes batteries, labour and freight is a marketing document. The useful question is which modules are covered, for how long, and how a claim is handled in practice.
Check instead: the spare-parts list and the response process, not the headline duration.
Why These Myths Persist
Because they are easy to print and hard to disprove at the quotation stage. They only become visible in year two, when the maintenance budget meets the installed hardware.
“Every myth survives until the first rainy season." — Project buyer, Ghana
The antidote is not scepticism. It is asking for the evidence behind each claim, and being willing to accept a smaller number that holds up.
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