Solved: Limited IQ8+ inverter output - JA Solar panels rated for 395 Watts putting out 250 watts (63% of max rated)

[aviateur17]

Just want to clarify that I'm not looking for the full 395 watt output. I'm wondering why the output doesn't show any peaking but is flat topped all the way from 10AM to 3PM at 250 watts per panel. I would hope that I see 290 watts max due to maxing out the IQ8+ inverter. I can't believe that 250 is the max for these panels. I'm hoping there's something I'm missing.

Hey all, hope you can guide me on how to figure out why I'm being limited on my panel output. I live in Minnesota so the sun angle is low and limited. I have two working ground mounted JA Solar panels rated for max 395 watts each (JA Solar 395w Solar Panel 108 Cell JA-JAM54-S31-395MR). On Full Sun days at Noon I'm only seeing each one put out 250 or 255 watts max for a total of 500 to 510 watts. Each panel has a Enphase IQ8+ inverter with no other Enphase gateway or communication gear. My understanding is that the Enphase IQ8+ should max out at 300 watts or 290 watts continuous. I'm shocked that I'm not seeing that on these 395 max watt rated panels. I'm using an Emporia Vue2 to monitor the power coming into the circuit. It's probably not the most accurate device but should be fairly accurate. I'm monitoring the power output through the day and graphing via Influx DB and I'll paste the graph below. Starting about 9:30AM I get 500Watts and then constant and same all through the day until about 3PM or 4PM and then the panels start to shade. What's odd is that there is no fluctuation in that output. The ambient temp is about 30 degrees F and the panels are warm to the touch but probably not warmer than 80 degrees F with direct sun. I've tried different angles and can't get them to put out much more than 255 watts a piece or 510 watts total. I don't exactly know how to test the panels directly. I've been trying to read about shorting the leads and measuring current and measuring open circuit voltage but that would be with no load and that wouldn't be accurate. You'd need some type of load. I wonder if the Enphase modules are limited unless you buy their Gateway for $4000 or whatever but I'm not too sure on that. I would guess they wouldn't be limited but I wouldn't rule that out. I did previously have a cheap Chinese inverter and was only getting 215 watts continuous when using that inverter. They are probably sitting at a 15 to 20 degree angle. I'll see if I can post pictures but I've tried changing the angle and see no difference. Any help on why I'm not seeing 290 watts/panel would be appreciated. I'll post the spec sheet for the panels and a graph of my output with full sun. The spikes in the graph during the day were me doing some testing of angles and such so don't mind them but you can see the flat top during the day which seems to mean that something is being limited.

Thanks for any suggestions!

 

[Steve_S]

You will NEVER see the exact 395+W unless the panels are at the exact angle & orientation for "Optimal" performance.
Example:
If a Fixed Mount array is set at 45 Degrees, directly Due South, that array will only generate its full potential when the sun angle matches and when the sun is directly due south matching the panels. In this example, Optimal Production woulkd occur twice a year, in March & September
~ Simplified Answer ~
The only way to optmize for monthly optimal production is to use very expensive tracking arrays.

 

[aviateur17]

You will NEVER see the exact 395+W unless the panels are at the exact angle & orientation for "Optimal" performance.
Example:
If a Fixed Mount array is set at 45 Degrees, directly Due South, that array will only generate its full potential when the sun angle matches and when the sun is directly due south matching the panels. In this example, Optimal Production woulkd occur twice a year, in March & September
~ Simplified Answer ~
The only way to optmize for monthly optimal production is to use very expensive tracking arrays.

View attachment 182715

Hi Steve, thanks for the reply. I have manually tried tilting the panels and don't get anything more than 510 watts from both panels combined. They are probably at a 15 to 20 degree angle. Is there a way to figure out if 63% of max rated output is all I'm going to get or if this is being limited to the panels? If the issue were the sun angle wouldn't the output peak around noon and peak sun and be less output before and after peak sun - aka not topping out or limited? Seems the output is constant at 500 watts between 10AM and 3PM with no peaking in between those times.

 

[Daddy Tanuki]

i have 16 JA solar panels that i bought new, and I have 20 sharp panels that i bought used at 5 years old, of which 12 are in one string and the other 8 are in a separate string. . both panels were rated at 200 watts. neither puts out its max power but the 12 Sharp's put out more than the 16 JA solar ones hands down, and they are five years older, i think JA solar is probably overrating their panels output in some fashion.. .so its more of if lightening strikes and the air is filled with fairy dust you might get most of what they are rated at.

thats just my experience with JA Solar. YMMV

 

[Danke]

What kind of load are you demanding of them?

 

[Pappion]

The sun has to shine through more atmosphere to reach Minnesota in the winter.

 

[400bird]

The bottom of the panels is shaded! That's definitely hurting production.

 

[Daddy Tanuki]

The bottom of the panels is shaded! That's definitely hurting production.

thats true i never even looked at the photos. but those photos might have been taken at the start or the end of the solar day and migh not be representative of actual shading during normal solar hours. only the OP knows this answer.

 

[400bird]

And I didn't look at the graph. The straight line limit at 500 watts is suspicious. There's something odd going on here

 

[aviateur17]

The sun has to shine through more atmosphere to reach Minnesota in the winter.

Pappion, thanks. How can I quantify that as far as panel production? In full sunlight if the panel was square to the sun what would I expect for production?

 

[aviateur17]

The bottom of the panels is shaded! That's definitely hurting production.

@400bird, Thanks! The picture I took isn't great. I took it like at 3:30PM when there was much shading. I'll take a better one in the next day or so when the sun is directly shining on the panels to get a better look at what is happening. In the middle of the day there shouldn't be any shading at the bottom of the panels.

 

[aviateur17]

And I didn't look at the graph. The straight line limit at 500 watts is suspicious. There's something odd going on here

@400bird, exactly, Why exactly 500 watts from 10AM to 3PM with no peaking. I'm starting to feel like the Enphase IQ8+ is limiting the output. I'm thinking maybe angling the panels like at 60 degrees like what they would be in the middle of summer so I can see if there is more of a curved characteristic output between 10AM and 3PM. I wonder if the Enphase IQ8+ without the comm gateway has some limiting by default. Wonder if there is someone who would let me borrow that equipment just to program them or to check the configuration.

 

[aviateur17]

What kind of load are you demanding of them?

@Danke, I have them hooked to my electrical panel in the house. I am charging my EV at 5 Amps during the entire day so that my electrical usage is higher than my solar production.

 

[Hedges]

"Maximum power current 12.81A"

What are the specs of IQ8?

 

[aviateur17]

"Maximum power current 12.81A"

What are the specs of IQ8?

 

[Hedges]

Seems like that should support > 250W/panel
10A would seem to as well, but IQ8-60-M-US says 245 peak, almost exactly what you're getting.
Better double-check label on inverter to be sure you really have the one you think.
The flat line just below 500W is too suspicious.

 

[aviateur17]

Seems like that should support > 250W/panel
10A would seem to as well, but IQ8-60-M-US says 245 peak, almost exactly what you're getting.
Better double-check label on inverter to be sure you really have the one you think.
The flat line just below 500W is too suspicious.

Thanks. Will do this tomorrow

 

[aviateur17]

I double checked the model numbers on the 2 Enphase IQ8 plus inverters and they are, in fact, IQ8+ versions. If the clipping was due to the solar panel I wouldn't expect a flat line at 250 watts between 10AM and 3PM but there to be some fluctuations so therefore I'm now pretty sure this is due to whatever factory configuration is in those Enphase inverters. The communication gateway is $600 and I'm wondering if that would be the next step. I'm also wondering if I can measure the DC current and voltage being put out by the panels using two meters - one inline and one measuring voltage - and if I'd actually measure a higher power or if that would be limited to 250 watts by the inverter as well. If anyone has a link to a guide on how to measure power out of a panel while that panel is under load I'd appreciate it.

 

[Hedges]

With an MC4 Y cable and MC4 to shrouded banana plugs, you can measure voltage while connected to inverter.
You could use two more MC4 to banana you could measure current, or use a DC clamp meter. Better to have 0.010A resolution than 0.100A; Harbor Freight has a clamp meter with such resolution for $100. Fluke, a more expensive model is needed. There are some others.

You can also measure a panel without MPPT by loading it with a resistor. For my particular "24V" 165W panels, I connected two 600/900/1500W heaters in parallel, set to provide 6 ohm load.

 

[Mike 134]

I agree with the others it's the inverters limiting output. As to seeing max output my Jinko panels have done it a few times when conditions were right. I.E. it was late March, (33-degree roof angle) blue bird day 25 degrees outside.