Can you exceed Solar Panels Nominal Max Power?

[brulaz]

My Rogue mppt records the daily peak Watts harvested from the solar panels. The other day it recorded a peak of 740W from a nominal 690W solar system (3 panels) while driving down the road.

Is this even possible?

The "nominal" power rating is based on Standard Test Conditions of irradiance and cell temps. Perhaps my real world conditions were more optimal? Or perhaps the Rogue is wrong?

[road-runner]

The most common situation for panels to exceed their rating is when cloud edges are present.

[ktmrfs]

just remember. the output spec's for a solar panel are not a maximum. they are a set of spec's for the output of the panel at a given temperature, air density, and luminous intensity of sunlight and light wavelengths. Once can check output against these spec's.

also the cells degrade over time as they get continued UV and IR exposure. Often the spec's are after a certain number of hours exposure.

And the spec is such that any panel pulled from the production line will meet the spec. They don't want to reject panels. so some or maybe most will exceed the spec to a noticeable degree.

In many cases panel temperature is higher than the test spec, and intensity is lower so output is less than the spec. but in some cases it certainly could be higher. driving down the road on a cool day with airflow will help keep the panel temperature near or below the spec'd temperature, get good sunlight and you could exceed the spec'd output for the test conditions.

and to complicate, many of the spec's I've seen are poorly stated. Imp, Isc should have a greater than or equal sign rather than just a number. Voc and Vmp should have a tolerance on the voltage.

[brulaz]

pianotuna wrote:
brulaz,

My panels came with a warning that in the first month they often would exceed their rated output. I normally see a peak of 17 amps--but in that first month I did see 21 amps.

Interesting, I was not aware of that issue.
2 of these panels are three years old and the third is two years old.

Have considered a 4th (now that 960W is the limit) but I've used most of the room on the roof. Any new panels will prolly be portable with their own controller.

Also, the Rogue does not report peak daily amps pumped into the batteries, just peak daily watts on the solar side. And that's only the peak watts that it used. More might have been available. It does report daily Ah on the battery side and daily Wh on solar side.

[pianotuna]

brulaz,

My panels came with a warning that in the first month they often would exceed their rated output. I normally see a peak of 17 amps--but in that first month I did see 21 amps.

[brulaz]

2oldman wrote:
My panels have never exceeded their ratings.

😞

[brulaz]

BFL13 wrote:
So the "peak watts" reading on the meter doesn't relate to how the controller can do twice as many watts at 24 than at 12 because the amps rating stays the same?

Was it the panels going above spec or just the watts being at 24 that did it? Is there a meter setting that didn't get swapped over with the change?

I know you can't get more just by changing from 12 to 24. I am wondering if it was a meter thing somehow. I know I am more than a little confused (again)

In fact I do get more watts out of my 690W of panels because of the switch to 24V. That's because the Rogue 30A mppt controller has a max limit of ~480W for a 12V system and twice that for a 24V system. So the gain only occurs when the solar Watts exceed the 480W. Under 480W, there's no difference.

And from what I'm reading here, panels can exceed their nominal rating, and my observed 10% over the rating may be real.

Rogue Manual wrote:
The maximum usable PV array power when taking into consideration system losses may be approximately calculated using the following formula, where Vb is the battery voltage: PV(watts) = (30 x Vb) / 0.90 (this assumes overall system efficiency of 90%).

Rogue uses 14.4V and 28.8V to get max 480W and 960W respectively.

[MEXICOWANDERER]

People don't like to read anymore so see spot run...
🙂 🙂 🙂



https://www.youtube.com/watch?v=i5fM8TE1INQ

[John___Angela]

Park against a snowy mountain side on a sunny day and watch the output climb. Neat

[2oldman]

My panels have never exceeded their ratings.

[Chum_lee]

Yes, solar panels can exceed their rated wattage. Think about their environment. Have you ever been driving and experienced temporarily blindness by a reflection from a highly polished surface like an oncoming windshield or a stainless steel trailer panel? The same thing happens to a solar panel. Hopefully your charge controller acts quickly enough to prevent electrical system damage.

Parking near a high rise building clad in reflective glass positioned . . . . just right . . . . can be brutal.

Chum lee

[MrWizard]

28v 30 amp charge is 840w that the controller can handle
28v 640w is 22.5x amps which is under the 30 amp rating, no problem

14v charge at 640 Watts would be 45 amps, so that is not going to happen the amps get limited, you would need a 60 amp controller

Im guessing everything is ok, and accurate,
The cooling effect of the air on the panels while driving, along with the cloud edge lensing effect, gave you your Higher than normal peak reading
Unless you had a huge increase in total accumulated watt hours , i would say that peak only lasted for a few seconds

[BFL13]

So the "peak watts" reading on the meter doesn't relate to how the controller can do twice as many watts at 24 than at 12 because the amps rating stays the same?

Was it the panels going above spec or just the watts being at 24 that did it? Is there a meter setting that didn't get swapped over with the change?

I know you can't get more just by changing from 12 to 24. I am wondering if it was a meter thing somehow. I know I am more than a little confused (again)

[valhalla360]

Yes, it is theoretically possible but I'll give you 2-1 odds, your meter is off.

The standard test for rating panels is near ideal conditions as they want to put the highest number they can on the panel.

[pianotuna]

BFL13,

That's the nice part about watts-hours, they don't change with the voltage.