Enphase M215 max power 225w ugh?

[cebury]

Panels don't max out. Give them 1200 W/m2 of irradiance, and all else being equal, they would output 120% of nameplate rating.

Thank you for speaking to that. I didn't think panels "clipped" like that either in real world installs at least.

[cebury]

I think we are talking about real world application - how many days within a calander year have your panels seen over 80% of nameplate?

I think that disproves your supposition.

[sensij]

I think we are talking about real world application - how many days within a calander year have your panels seen over 80% of nameplate?

My PVOutput.org data is available online for anyone to see, link in my signature.

My system went fully online April 10, 2015. I'll assume you are looking for days in which the power over 80% is sustained for at least 1 hour, not instantaneous readings from cloud effect bursts of irradiance, which can actually result in output that exceeds 100% of STC. My inverter clips at 3000 W, and I have 3120 W of panels, so I can't provide evidence of that in my own data, except to say there were a few times last year that the clipping limit was hit.

80% of 3120 = 2496... so we are looking for days in which power was sustained at that level or higher... just scanning through visually, I see the following:

Apr 2015 - 16 days
May 2015 - 17 days
June 2015 - 19 days
July 2015 - 23 days
Aug 2015 - 19 days
Sept 2015 - 8 days
Jan 2016 - 1 day (really, this was sustained cloud effect on a very cold day, Jan 8th)

83 days by my count, probably around 100 over a full year. My system is just starting to touch 2500 W now, so I'd expect early in March that sustained power above 80% will be typical for clear days again.

Please don't take my posts in this thread the wrong way... I support the idea that a 280 W panel is OK to pair with an M215... in fact, even if my system clipped at 2500 W (about the same DC to AC ratio), the actual energy lost would not be a huge number, and there are definitely situations in which the most cost effective choice is to just accept some clipping than to try to design a system that produces the maximum possible energy.

[cebury]

Another member, about a year ago, posted his output where it looked like the M215's were clipping with 275 watt panels - I'm now convinced that the panels themselves were

maxed out for the sun & temp they were seeing.

Maybe I'm struggling with Mikes definition of clipping, because I'd call the last line normal operating behavior, not clipping. Assuming those panels were hot, on a roof etc, and a cold breeze came by they would produce tiny bit more. Clipping is the true bottleneck caused by some internal component, usually an electrical one.

My question is how many places in the US, with a typical residential or commercial install, would provide the optimum conditions where a panel could start clipping? Probably some high elevation with clean air, in the north for a short period of the year?

http://www2.enphase.com/global/files/Enphase_White_Paper_Module_Rightsizing.pdf

Enphase gathered actual data from 260w modules paired with m215 in 2012 they observed clipping within Enlighten "at its max output power 225w". Fwiw

[sensij]

My question is how many places in the US, with a typical residential or commercial install, would provide the optimum conditions where a panel could start clipping? Probably some high elevation with clean air, in the north for a short period of the year?

Again, a panel can't clip. The inverter clips. 3000 W of panels on a 6000 W inverter would never "clip", anywhere in the world, because no set of environmental conditions (irradiance + cooling) will occur that would cause those panels to be capable of generating 60000 W.

Conversely, a 6000 W array on a 3000 W inverter would "clip" almost every day in most installations.

[cebury]

Again, a panel can't clip. The inverter clips. 3000 W of panels on a 6000 W inverter would never "clip", anywhere in the world, because no set of environmental conditions (irradiance + cooling) will occur that would cause those panels to be capable of generating 60000 W.

Conversely, a 6000 W array on a 3000 W inverter would "clip" almost every day in most installations.

I understand. My sentence above was supposed to include double quotes around clip, for the panel, based on Mikes definition. It was a lead-in question.

Leaving the AC conversion out of the equation, Whatever output appears to be the max for a panel, if you add more irradiance (and lower temp, within a certain range) it will always produce more DC watts. Period. That's how my lay understanding of panels work.

My question is better stated, where are the installs that panels would consistently produce greater than their nameplate rating, such to confuse someone to believe the panel itself is "clipping", despite the inverter not being saturated. The question is irrelevant now.

[MikeInRialto]

Ok - I shouldn't have used "clipping" for panels - Instead, I should've as cebury wrote "maxed out" under current conditions.

So to rephrase with 275 watt panels - we more often see the panel maxing out and not the M215 micros clipping. And the question... How many times in a calendar year has anyone seen their panels producing 85% or better of the nameplate rating? And for how long? 85% of a 275 watt panel is 233.75 - right around were a M215 MIGHT begin to clip.

[sensij]

If panels aren't being clipped by the inverter, and the mppt is achieving its objective, then the panels are *always* maxing out for the current conditions.

Again, the basic premise is fine... 275 W usually pairs well with M215. In some cases, going to m250's can be cost effective, other times, not.

[bvmm]

Ok -And the question... How many times in a calendar year has anyone seen their panels producing 85% or better of the nameplate rating? And for how long?

85% of a 250W panel is about 212W. The attached figure shows the number of hours that my best panel has produced more than a given power level. It produces above the 85% level about 2% of the time.

[MikeInRialto]

My point exactly! Panels are ALMOST ALWAYS, specifically in your case 98%, below 85% of nameplate. In my area it looks like the norm is that they are mostly 70-78% of nameplate