Solar panel ratings

About ten or so years ago my 22a, 400w MPPT controller was for a short period of time was holding at just over 27a…But strangely, this was on the Northern Calif coast, immersed in a low beach fog on what was otherwise a cloudless summertime day - this, with an ‘aura’ of bright but highly diffused sunshine penetrating through…I’ve often since wondered about this curiosity, but can only surmise that the grains of moisture in the air in concert with the sunlight sorta acted like a parabolic mirror - just speculating…

3 tons

It happens quite often in Colorado. The cooler temperatures, higher elevations with less atmospheric diffusion and clear skies are big factors. My controller summarizes the day's output/input with one item being Peak Watts. It is not unusual to see a peak of over 400 watts on a system rated at 370 watts. I don't have the ability to see a graphical presentation of the day's production, so I have no idea of the duration or timing of the peak events, but they do occur. I usually tilt my panels to an "optimum" angle. The panels are now 12 years old.

Two of the standard testing conditions for solar panels are sea level at 25C (77F). Both of these conditions are easily exceeded in Colorado. At 10,000 feet, you are above more than 25 percent of the atmosphere. 7800 feet elevation in Arizona will give you about the same result.

It's a standardized rating based on a specific set of test conditions. Exceed those conditions and it can put out more power.

Of course, those test conditions are near (but not at) perfect conditions. On rare occasions, you may exceed those conditions.

And as someone said, exceeding the rating by 0.3% is likely within the margin for error on the rating.

I've never seen that with my system, but congratulations!

Cptnvideo wrote:
I noticed the Victron 150/100 MPPT controller app showed a max power of 1204 watts.

A difference of 4 watts is probably within the measurement margin of error of your controller - not to mention the tolerance of your solar panels' specification.

'one sun' is 1000 W/m2
this 2013 graph of a seemingly clear blue sky day, may 31, from milford utah, note the peak is over 1000.



Solar irradiance - wiki - Irradiance on Earth's surface
"Average annual solar radiation arriving at the top of the Earth's atmosphere is roughly 1361 W/m2.[30] The Sun's rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W/m2 at sea level on a clear day. When 1361 W/m2 is arriving above the atmosphere (when the sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m2, and global radiation on a horizontal surface at ground level is about 1120 W/m2.[31] The latter figure includes radiation scattered or reemitted by the atmosphere and surroundings. The actual figure varies with the Sun's angle and atmospheric circumstances. Ignoring clouds, the daily average insolation for the Earth is approximately 6 kWh/m2 = 21.6 MJ/m2."

You lose about 10% watts from panel heating. To go over you need to be high elevation in ambient cold to make up the heat loss and then some compared with "standard" conditions.

Cptnvideo,

Look up cloud lensing and solar panels.

It is entirely possible to exceed the rated output, especially in the first few months of panel operation.

Panel ratings are under PERFECT solar conditions of "one sun".

Yes. Once. Under close to perfect solar charging conditions, clean panels and with wet batteries at a SOC of 45%…305 watts. Never again.