Enphase Microinverter Selection

[troxel]

Hello

I am putting together a single array solar system using Q-cells 400-watt panel. This panel has a NMOT of 299.6 Watts therefore ~1.25 amps @ 240 volts.

I am looking at using Enphase IQ8 micro inverters but wonder which to pair with these panels.

	IQ8Plus	IQ8M
Max Amps	1.21	1.35
Max Inverters per 20 Amp Circuit	13	11

I am in Southern California at Lat 34 degrees and installing on a 2/12 roof with angle ~10 degrees so at summer solstice I would be close to optimal incident angle.

Question to maximize yearly Kwh output should I go with IQ8Plus with 12 Panels/inverters or IQ8M with11 Panels/inverters?

Seems that in ideal condition I will get some clipping with the IQ8Plus but overall, I would produce more energy with the 12 panels/IQ8Plus than with the 11 panel/IQ8M.

Is there any sort of online app to help analyze this? Or from the experts here which approach is advised.

 

[svetz]

I am in Southern California at Lat 34 degrees and installing on a 2/12 roof with angle ~10 degrees so at summer solstice I would be close to optimal incident angle.

It's more than latitude, the best optimum also has to do with the weather. For example, with my 25° latitude to optimize for summer, you might think just a few degrees of tilt. But, we get tons of rain during the summer so I'd be better off with a higher angle (which I can't do because of hurricane-force winds ; -).

But in general, folks either optimize for when they need the most power or to optimize for year-round if they've a good net-metering agreement. A program like SAM can help you figure out the best tilt.

Question to maximize yearly Kwh output should I go with IQ8Plus with 12 Panels/inverters or IQ8M with11 Panels/inverters?

Your panels will rarely produce the full-rated wattage. SAM can calculate the clipping throughout the year for each microinverter. You'll have less clipping with the M's obviously, but you might be surprised at how little. Not so obvious is the IQ8+ kicks in at a lower voltage... so you might end up making more power from low-light conditions (although current generally varies a lot more than voltage). There's some low-light data on LGs in #53.

Is there any sort of online app to help analyze this?

This link will tell which microinverters are compatible with any given solar panel.

 

[troxel]

It's more than latitude, the best optimum also has to do with the weather. For example, with my 25° latitude to optimize for summer, you might think just a few degrees of tilt. But, we get tons of rain during the summer so I'd be better off with a higher angle (which I can't do because of hurricane-force winds ; -).

But in general, folks either optimize for when they need the most power or to optimize for year-round if they've a good net-metering agreement. A program like SAM can help you figure out the best tilt.


Your panels will rarely produce the full-rated wattage. SAM can calculate the clipping throughout the year for each microinverter. You'll have less clipping with the M's obviously, but you might be surprised at how little. Not so obvious is the IQ8+ kicks in at a lower voltage... so you might end up making more power from low-light conditions (although current generally varies a lot more than voltage). There's some low-light data on LGs in #53.


This link will tell which microinverters are compatible with any given solar panel.

Thanks for the links and the response. I suspect you right the inverters will rarely clip and I am leaning towards the plus.

 

[flyer5]

It's more than latitude, the best optimum also has to do with the weather. For example, with my 25° latitude to optimize for summer, you might think just a few degrees of tilt. But, we get tons of rain during the summer so I'd be better off with a higher angle (which I can't do because of hurricane-force winds ; -).

But in general, folks either optimize for when they need the most power or to optimize for year-round if they've a good net-metering agreement. A program like SAM can help you figure out the best tilt.


Your panels will rarely produce the full-rated wattage. SAM can calculate the clipping throughout the year for each microinverter. You'll have less clipping with the M's obviously, but you might be surprised at how little. Not so obvious is the IQ8+ kicks in at a lower voltage... so you might end up making more power from low-light conditions (although current generally varies a lot more than voltage). There's some low-light data on LGs in #53.


This link will tell which microinverters are compatible with any given solar panel.

I trying to decide myself on which to use. Your post has me questioning what I want to use. I was planning to go with the IQ8H . But now with clipping being thrown into this and start voltages ( I am a newbie ) I am not sure. From what I can see all the IQ8s have a start voltage of 30 so that should not be a factor, no? Am I looking at this correctly? Thank you

 

[svetz]

... now with clipping being thrown into this and start voltages ( I am a newbie ) I am not sure. From what I can see all the IQ8s have a start voltage of 30 so that should not be a factor, no?

You can use a program like SAM to calculate the amount of clipping you're likely to see for different inverters at different orientations. Watch the video tutorials, they'll get you jumpstarted.

 

[flyer5]

You can use a program like SAM to calculate the amount of clipping you're likely to see for different inverters at different orientations. Watch the video tutorials, they'll get you jumpstarted.

Thank You

 

[atom88]

I have an IQ8+ based system with the Enphase product and 13x QCell 400 W panels. I was seeing clipping during the first 7 days of my system. I live just south of Salt Lake City, UT with a 180 degree azimuth tilt. I was told I was the FIRST PERSON in the state of UTAH to receive the IQ 8 based system.

I have the IQ8PLUS-72-2-US micro-inverters, rated up to 300 VA.

My solar installer company didn't discuss the design with me when selecting the inverters and now I'm asking them if they can upgrade the inverters so I don't get clipping and loose out on missed opportunity to generate power.
I didn't even know anything about "solar clipping" until after the system was installed and working and I saw it in the enphase / enlighten app.
I have a 2nd home with an IQ7 based system with a nice curve (no clipping), so I had something to compare it against and knew something wasn't right.

 

[flahdaguy]

I too have that same question. I'm planning on Qcell G10 400's with Enphase M.I.'s. Operationally speaking, what have you seen? Did you go with a "iq8+, M, or A" ?? Would you change that choice? Thank you!

 

[foggysail]

Below shows how I made my inverter choice. One thing for sure.............I DID NOT WANT POWER CLIPPING!

PLUS = 290W continuous maximum output power
M = 325
A = 349
H = 380

EDITED TEXT BELOW:

I am waiting activation of my newly installed 28 each 400W Canadian panels. I changed my choice of inverters at the last minute from the plus to the A's, about 2 days prior to the installation. Sure NMOT represents expected but I theorized there will be times that I just might get 350 or so watts out of my panels. If that turns out to be a good assumption, I will lose about 60W/panel. Even if I am lucky to enjoy 350W for only an hour a day the losses with an PLUS (note, I mistakenly posted an A instead of a plus in my post before this correction) inverter are significant.

The difference is 349 - 290 = 59W/panel resulting in a system loss is 28 X 59 = 1.652 KWH. If this occurs for 300 days/year or so, my yearly loss would be 495.6 KWH!!! Heck, that is almost a full month's current electric usage.

The cost difference was small, I am happy I demanded better inverters before it was too late. There is no reason for me to have gone with an H inverter because I think I am pushing my expectations with my sometimes 350 or so watts/panel.

 

[jshinn]

Yesterday was my first day running my system.

System:
24 REC 405 Alpha Pure's with iQ8M's
Northern California, Panel Pitch 19 deg facing 230 deg SW

The most a single panel was producing was around 280w. Hopefully I get closer to 330w in the summer.

Still trying to understand the data. 34% energy independence, seems off. I feel like my system produces more than I used. I have it set to "Load and Solar" in the Config.

Also, do my settings look correct? Production Meter L1 + L2, and Consumption Meter L1 + L2? I currently only run the L1's through the production meter ring. I can post pics, just trying to make sure my monitoring is set up correct.

 

[foggysail]

Yesterday was my first day running my system.

System:
24 REC 405 Alpha Pure's with iQ8M's
Northern California, Panel Pitch 19 deg facing 230 deg SW

The most a single panel was producing was around 280w. Hopefully I get closer to 330w in the summer.

Still trying to understand the data. 34% energy independence, seems off. I feel like my system produces more than I used. I have it set to "Load and Solar" in the Config.

Also, do my settings look correct? Production Meter L1 + L2, and Consumption Meter L1 + L2? I currently only run the L1's through the production meter ring. I can post pics, just trying to make sure my monitoring is set up correct.


View attachment 115222

Beautiful attachment! My system has the last inspection (electrical) schedule for Tuesday next week and then I wait for grid tie.

I tried to use your graph to get numbers but something in my calculations does not make sense. For example, the peak power shown is about 1.7KWH being produced with 24 panels or only 75W peak/panel. YEAH......not at all challenging your numbers because I expect about the same panel power from my 400W Canadian panels as you calculated for yours. And I am also thinking I might get close to 330W or so for some periods during the summer.

And I almost got stuck with the IQ8plus inverters with clipping above 290W. I made last minute changes to my installation by add another 2 panels and went with the IQ8A inverters. If I get clipping it will not be much.

 

[jshinn]

Thats around 1.7KWH (1.7ish x 24) per panel produced for that day. I also figured out the energy independence data, see attachment. I'm adding 4 more iQ8m's because I got a great deal on them, combined with 4 LG NeON 2 370's on a more south facing roof section. I will post my data. I'm curious if they will produce close to the 405's. I will probably have to go through the PG&E process again since I'm changing my system. I just got their approval on Oct. 7th.

 

[jshinn]

Beautiful attachment! My system has the last inspection (electrical) schedule for Tuesday next week and then I wait for grid tie.

I tried to use your graph to get numbers but something in my calculations does not make sense. For example, the peak power shown is about 1.7KWH being produced with 24 panels or only 75W peak/panel. YEAH......not at all challenging your numbers because I expect about the same panel power from my 400W Canadian panels as you calculated for yours. And I am also thinking I might get close to 330W or so for some periods during the summer.

And I almost got stuck with the IQ8plus inverters with clipping above 290W. I made last minute changes to my installation by add another 2 panels and went with the IQ8A inverters. If I get clipping it will not be much.

Did your designer list what gauge wire they are running from your rooftop junction box to your combiner box? I went with 12 AWG, but I’m thinking I should have went with 10 AWG.

My distances are 54 ft from the junction to the combiner, with 3 branches of 72 cell landscape length q-cables. Branches are 2x 11 iq8m’s and 1 x 2 iq8m’s. I need to recalculate my voltage rise, and I’m not sure if 10 AWG will give me a little more wattage. I designed my system for easy upgrade, so I was debating swapping to 10 AWG eventually.

 

[Bob in Tucson]

In case you have not seen it, Enphase has a technical document for calculating voltage rise. It's a pdf and it's here.

 

[jshinn]

In case you have not seen it, Enphase has a technical document for calculating voltage rise. It's a pdf and it's here.

The design software I used listed 12 AWG, but after using the calculations from that pdf, I should have went with 10 AWG for my home run. It’s close, so it probably won’t make a difference, but I might make the change just because. My system seems fine, but in the mornings before the sun comes up I get an “AC voltage out of range” entry in my event logs.

 

[Bob in Tucson]

Funny, I used 10 AWG for mine and probably should have used 8.

 

[foggysail]

Did your designer list what gauge wire they are running from your rooftop junction box to your combiner box? I went with 12 AWG, but I’m thinking I should have went with 10 AWG.

My distances are 54 ft from the junction to the combiner, with 3 branches of 72 cell landscape length q-cables. Branches are 2x 11 iq8m’s and 1 x 2 iq8m’s. I need to recalculate my voltage rise, and I’m not sure if 10 AWG will give me a little more wattage. I designed my system for easy upgrade, so I was debating swapping to 10 AWG eventually.

General comment: IMPRESSIVE!!

I have about the same distance (3 circuits) without actually measuring. I have not run the numbers needed to calculate my voltage drop between the panels and the distribution box which I believe is OK. For your installation with 24 panels at the highest output of 350W/panel (wishful thinking). Total current from 24 microinverters, 350W/inverter @240V is 35a or 11.6a/string. #12 wire has a DC resistance of 1.6 X 10^-3 ohms/ft. For 100 feet your drop is just under 2V and that is a rare occasion when you get 350W/panel.

One small note, the above is using a DC resistance. With AC there is a skin effect that will slightly increase the resistance

 

[foggysail]

MORE---

I did not interfere with my installation's design and after reading and responding above to JSHINN's posts I thought it important to check MY wiring between the inverters and the Enphase distribution box. So I pulled the cover and found..................#10 wire for each solar inverter to the distribution box's three circuits.

 

[foggysail]

Funny, I used 10 AWG for mine and probably should have used 8.

8 AWG is not fun to work with. Run the numbers to get a better understanding of what your voltage drop might be under worse case circumstances.

 

[jshinn]

MORE---

I did not interfere with my installation's design and after reading and responding above to JSHINN's posts I thought it important to check MY wiring between the inverters and the Enphase distribution box. So I pulled the cover and found..................#10 wire for each solar inverter to the distribution box's three circuits.

That's good that you have #10, no need to worry. I will upgrade my #12's eventually if needed.

Today I got my 4 LG (NeON 2 370) panels that I bought on clearance, and should have those up tonight. My 24 REC 405AA's are still getting right around 280w, not near the listed 309w NMOT (Probably October Sun, looking forward to the summer) and nowhere near to my iQ8m's 325w limit. I hope the LG's produce near the 280w of the more expensive 405's. They do have a small advantage of facing more south.

Wiring Question:

My system:

1x IQ Combiner 4 with 3 circuits running #12 54 feet to the junction box (QM-JBX-RL01-B1).

From the junction box:
Circuit #1: 1 x 11 connecter Q Cable (Landscape, 72 cell) connected to 11 iQ8m's with 11 REC405aa's
Circuit #2: 1 x 11 connecter Q Cable (Landscape, 72 cell) connected to 11 iQ8m's with 11 REC405aa's
Circuit #3: 1 x 2 connecter Q Cable (Landscape, 72 cell) connected to 2 iQ8m's with 2 REC405aa's

I've done some research, but I would like some other opinions.

My plan for adding the 4 LG's:

At the end of Circuit #3, I plan on adding a small junction box with conduit running 1 ground for the racking, and pair of black and red #10 wires 25 feet to another roof section into junction box. Exiting this junction box will be the ground wire connecting the small array to the main array racking, and a 4 connecter Q Cable (Portrait mode) connecting to the 4 new iQ8m's.

Circuit #3 will end having 6 total inverter/panels.

Everything seems to code, including the new 50amp Breaker and Fuse I will have to upgrade to. My question is regarding the #10 (30amp) wire sitting between the 2 #12 (20amp) Q Cable sections. I have the required length in #10 sitting around not used, so I plan on using it. I'm not an electrician, but my thought is that since the 4 iQ8m's can only push at max 5.4 amps (1.35a x 4), never coming close to a #12 limit, it should not be a problem. Any thoughts?

Basically not needing to protect he number #12 Q cable following a #10, since the other #12 Q cable will be supplying the #10.