Over paneling IQ7

[ArthurEld]

I want to connect 4 100W panels to 1 IQ7 micro inverter.
VOC=22.4 ISC=5.92A
IQ7 max V=50 max Amps=10

I think I should connect them 2S2P. Which should give me 44.8V and 11.84A.
From what I have found I should be ok because I can go over on the amps but I can't go over volts.
I know cold weather is also a consideration. I am in FL so I think the minimum temp is 25 degrees.
I assume I can connect 2 of the panels together with the cables on the panels. Then I have to use 2-1 adapters for the parallel connections.

HQST-100P data sheet - https://hqsolarpower.com/content/HQST-100P-Spec.pdf
IQ7 data sheet - https://enphase.com/download/iq7-iq7-microinverter-data-sheet

Branch connectors - https://www.amazon.com/dp/B08T1Q8PF7/ref=sspa_dk_detail_5

Does it sound like I am doing this properly? I don't want to burn up my IQ7 that I just paid $90 for.

 

[n2aws]

NEC 690.7(A) has a temperature correction chart for solar panels.

A quick google search tells me that the record low for palm harbor FL is 28F.

Looking at the chart, that puts you in the 12% bracket.

44.8 * 1.12 = 50.176, which is above the inverters 50V max.


I honestly don't know if exceeding it by .176 volts would let the smoke out, but for me personally, I'd say thats too close for comfort.

In my opinion, you want to design for the extremes. During those extremes is when you'd likely be relying on it the most, and that "safety factor" ensures that during the non-extremes, we aren't overdriving the equipment.

 

[zanydroid]

Enphase micros are dicey to overpanel, they have kind of narrow electrical range?

Why use the NEC table when VOC compensation is in the data sheet? The NEC table is pessimistic

 

[n2aws]

Enphase micros are dicey to overpanel, they have kind of narrow electrical range?

Why use the NEC table when VOC compensation is in the data sheet? The NEC table is pessimistic

When it comes to safety margins, I prefer pessimistic, to be honest.

 

[zanydroid]

When it comes to safety margins, I prefer pessimistic, to be honest.

Fair enough.

Probably with the NEC table it's not as important to stack on extra safety margin on top (I think it's like 20% or 30% higher V/deltaT constant than most panels).

Another thing to consider is bypassing 1/3 of one panel in each parallel branch by removing the bypass diode and replacing it with a wire. That will for sure given enough margin, at the cost of dropping 33W STC in each branch.

 

[Consumerbot3418]

Any reason you don't go 4P? Trying to save on MC4 connectors?

I'm with @n2aws, don't see why you'd ever want to approach vmax. I can tell you that I briefly paralleled an IQ7 (2P 60-cell panels) and it worked fine.

 

[zanydroid]

You can also get a higher voltage IQ7. In Enphase parlance alphabet soup of suffixes corresponds to slightly higher/lower voltage and current limits.

4P ISC is I'm pretty sure above the fuse limit of any IQ7 (short of maybe some commercial chonker)

 

[Consumerbot3418]

Another thing to consider is bypassing 1/3 of one panel in each parallel branch by removing the bypass diode and replacing it with a wire. That will for sure given enough margin, at the cost of dropping 33W STC in each branch.

Interesting solution... I've wondered about this before. Seems like a diode, resistor, or in this case, even an inline fuse might be enough to drop the voltage into tolerance.

 

[zanydroid]

Interesting solution... I've wondered about this before. Seems like a diode, resistor, or in this case, even an inline fuse might be enough to drop the voltage into tolerance.

Sure, you can buy diodes that are rated to work as blocking diodes for this, and it will waste a lot less than bypassing 1/3 of a panel. And it can be done after combining to reduce the parts count.

This will, however, burn all the voltage drop as extra heat that needs to be handled properly.

 

[Hedges]

I wouldn't personally be concerned about 0.2V
I think your Voc and temperature coefficient says you're OK to -13.7 degrees C, 7.3 degrees F. Check the math.

It may clip power occasionally. How about the 2s2p having 2s of two different orientations?

 

[zanydroid]

Branch connectors - https://www.amazon.com/dp/B08T1Q8PF7/ref=sspa_dk_detail_5

Are those official MC4 connectors or listed to be cross compatible with MC4? I'm pretty sure the IQ7 side is real MC4.

(and do you care for something this small, if it melts or burns)

FWIW Staubli makes this exact thing in official MC4.

 

[ArthurEld]

Are those official MC4 connectors or listed to be cross compatible with MC4? I'm pretty sure the IQ7 side is real MC4.

(and do you care for something this small, if it melts or burns)

FWIW Staubli makes this exact thing in official MC4.

I would prefer that nothing burns or melts. But I am willing to experiment since this is a small setup.

 

[zanydroid]

I was looking at those the other day while answering another thread and noticed that Monroe Titan carries the official version of those combiners

 

[ArthurEld]

I wouldn't personally be concerned about 0.2V
I think your Voc and temperature coefficient says you're OK to -13.7 degrees C, 7.3 degrees F. Check the math.

It may clip power occasionally. How about the 2s2p having 2s of two different orientations?

The current plan is to have them all in the same direction. I am just making a simple awning over the door of my shed. I thought going with 2s2p gets me closest to the tolerance of the iq7 but I didn't realize I could violate the voltage tolerance from cold temps.

 

[ArthurEld]

I was looking at those the other day while answering another thread and noticed that Monroe Titan carries the official version of those combiners

Are those official MC4 connectors or listed to be cross compatible with MC4? I'm pretty sure the IQ7 side is real MC4.

(and do you care for something this small, if it melts or burns)

FWIW Staubli makes this exact thing in official MC4.

I will look into these better MC4 connectors. Thanks for the suggestion

 

[zanydroid]

I will look into these better MC4 connectors. Thanks for the suggestion

They’re called branch connectors here:

Connectors | Staubli Multi-Contact | OneMonroe Titan

Staubli Multi-Contact products provided by OneMonroe Titan

titanwnc.com

The matched listed connector thing was added to code a few years back after fires and melted connectors were discovered. I’ve heard of situations on the forum where after 5 years close to 100% of unmatched connectors were melted.