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?

[brulaz]

mike-s wrote:

BFL13 wrote:
Just a sec! Are you comparing 12v with 24v watts?

Like there's a difference?

Yes, I'm comparing 12V and 24V DC watts.

And since switching to 24V, I'm using Wh a lot more than the Ah standard. So my battery bank went from ~ 430Ah @12V to ~215Ah @24V, but is ~5.16kWh for both.

A problem is that this 5.16kWh is based on the 20hr battery standard, and I see that Trojan only reports kWh (and Ah) for the 100hr rate in their T-105RE brochure.

Things can get confusing fast ...

[wa8yxm]

The max power of the panel. or the rating, is based on how much sun the manufacturer tings will be hitting the panels.. If it is overly sunny, And it is now days on occasion, you will get more power than the rating.

There are ways to make it happen on purpose

Yes, there is danger of "Burning out" the panel but I do not know how great it is.

[mike-s]

BFL13 wrote:
Just a sec! Are you comparing 12v with 24v watts?

Like there's a difference?

[BFL13]

brulaz wrote:
Ah ok. I'll believe the Peak Watts then.

The Rogue mppt will not pump out more than 30-31A.
So when my batts were 12V I never got close to the "nominal" solar rating of 690W. But now that I've reconfigured them to 24V I'm getting these > 690W readings.

.

Just a sec! Are you comparing 12v with 24v watts?

[brulaz]

Ah ok. I'll believe the Peak Watts then.

The Rogue mppt will not pump out more than 30-31A.
So when my batts were 12V I never got close to the "nominal" solar rating of 690W. But now that I've reconfigured them to 24V I'm getting these > 690W readings.

Thanks all.

P.S. Not high altitude, near Montreal, Quebec. Air temp <25C, speed 60-65 mph, major freeway, clear sky, prolly happened around Noon, 27 June.

EDIT: Actually, not clear sky. Wife reminds me that it was "mostly sunny" with occasional cumulus? clouds. So perhaps the cloud effect helped. It was a beautiful summer day anyway ... 🙂

[red31]

spec is based on 20C and 1000 wh/meter squared. this is exceeded often.

[time2roll]

And driving will have a cooling effect to increase output.
Otherwise stand some mirrors up and you will put them in overdrive.

[Lwiddis]

As said in cool temps and bright light, yes. Mine do.

[BFL13]

Of course you can. That is why they warn you about the controller's voltage (Voc) input limit when you are camping in cold temperatures, EG.

Some controllers are self-limiting for power though ( power not voltage) to keep them from exceeding their amps ratings. (Sometimes called, "clipping the amps.")

You forgot to mention STC includes air pressure, which would have been the issue here, since cold wasn't likely it. Were you driving so fast you got some wing lift effect? 🙂

When jimindenver used to camp at the top of Pike's Peak, he got all sorts of unusual readings on his solar set-up. 🙂

EDIT--actually it would be hard to exceed the power rating since the panels if in any sun will be hotter than ambient and their power ratings will be much lower accordingly. You would need some actual measurements of the various factors to know what was happening.

EDIT some more--if there is wing lift effect so air pressure above the panel is reduced, then this will be of concern to everyone who has roof-mounted panels?

[MrWizard]

High altitude and cool weather m might produce higher ratings

Or
Lensing effect