Are Renogy 100w panels underrated?

[gkb2016]

I bought a Renogy kit with the hard panels (I.e. not the thin flexible panels) and mounted 3 100w panels on my van, for 300w.

Anyways, in really strong direct sunlight, I have noticed the app says I am getting over 300w of power … is it normal for panels to output over their rated output in direct sunlight with no obstructions? Of course the other possibility is one or a combination the app, bluetooth dongle device or charge controller are inaccurate.

Earlier took a screenshot of the app showing 351w, quite impressive if accurate especially considering there are supposed to be a certain % of losses.

 

[Spaceman Spiff]

Solar panels are rated at 25ºC and an irradiance of 1000W/m2. If your panel is cooler and/or if you are getting more sun your panel will produce more than its rating.

 

[gkb2016]

Solar panels are rated at 25ºC and an irradiance of 1000W/m2. If your panel is cooler and/or if you are getting more sun your panel will produce more than its rating.

Very interesting. Not sure how I haven’t seen anyone mention that before!

 

[frater secessus]

is it normal for panels to output over their rated output in direct sunlight with no obstructions?

It's not common (don't count on such high yields) but it does happen. It makes more sense when we remember Pmax = Vmp x Imp*. Let's consider a 100w Renogy panel with Vmp = 17.8v and Imp = 5.62. Multiplying those two values gives us 100.036w. Anything that increases either value will increase panel output.**

• high altitudes can have higher irradience (less air to filter), increasing Imp
• cloud-edge effect can increase irradience (reflection), increasing Imp
• very low temperatures (typically below freezing, a function of cell temp derating) can increase Vmp
• etc

It's possible the panels are underspec (actual power is higher than rating) due to manufacturing variations.

Not sure how I haven’t seen anyone mention that before!

It's rare and not an issue for most end-users.*** Here's an overview of such factors.

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* Pmax is the maximum power. Vmp is the Voltage at which the panel makes max power. Imp is the current (Intensity, for historical reasons) at which the panel makes maximum power.
** likewise, anything that reduces the values will reduce output
*** with the exception of PWM users designing their own systems, who often size the controller +20% to allow for overcurrent conditions

 

[JDub]

YEAH! That's what I was gonna say but those guys got in ahead of me... Yeah... Really... Not joking...