WARNING - These panels are more like nominal 150 watts. From
my testing they are no where near a 250 watt.
Features: 1. Brand products,meeting Australia standards; 2. Certified by TUV,IEC(IEC61730 and IEC61215),CE,ISO9001; 3. Easy to fit via screw(or glue); 4. Bypass diode built in;IP65 Rated Waterproof Junction Box and MC4 Connector; 5. Laminated Tough,durable,not shatter; 6. Waterproof,Weather and Corrosion resistance; 7. High Efficiency Grade A Solar Cells, Over 25 Years Power Output lifetime; 8. 30 days money back guarantee;1 Year Workmanship Warranty; Specification: Max Power: 250W Max Power Voltage: 19.8V Max Power Current: 12.6A Open-Circuit Voltage: 22.8V Short-Circuit Current: 13.2A Power Specification: STC:AM1.5,1000W/m2, 25°C Cell Grade: Grade A Application Class: Class A Temperature Range: -40°C-85°C Thickness:2.5mm Net Weight: 3.5kg/pc Size: 1010x810mm Package Included: 1 X 250W Flexible Solar Panel
The test panel was brand new, straigh out of the box.
The maximum open circuit voltage I could obtain from the panel was just below 19v. The maximum current was 7 amps. Say 19 x 7 = 133 Watts . 133 Watts is a little over half the rated power. I accept that that irradiance levels, thermal coefficients, and accuracy of the test equipment may affect the results. However, 133 Watts falls far short of the advertised 250 Watts. The panel was tested in the full December midday Queensland sun.
I contacted the supplier and they responded:
"Please understand, solar panel output will depend on sunlight and installation condition etc. Manufacturer max power specification is basic on standard test condition(STC):AM1.5,1000W/m2, 25°C ONLY. Any output will be possible if different condition."
I agree the Standard Test Conditions (STC) were not strictly meet, however, full midday sunshine in a Queensland summer must come close. The PV panel were not in the sun for long to avoid heating before the measurements were taken. I could allow 10%, even 20% of loss for less that optimal test conditions, however, 133 Watts out of 250 Watts would easily classify as "not as advertised".