Solar panel output

[bikerider4818]

I have 10 X 400w (front side only) Jinko bifacial solar panels from Santan Solar. I tested each panel when I received them and they seemed okay. I'm assuming they should have a potential of 4000-5000 watts in perfect conditions, but I've never seen them produce more than about 2500w at anyone time during last summer. I have them set facing mostly south at about 29 degrees which is the optimal year round angle for my area. Today is a very gray cloudy day and they are only producing 500-700w total at noon time. Is this normal? My readings are from my 6000xp inverter.
Second question... Is there a more optimal wiring configuration I should be using? I have them setup in series with two separate arrays (5 panels each) with two seperate lines going to my inverter since it has two mppt inputs. Would it make any difference to have the two arrays joined in parallel with only one line going to the inverter (assuming the amps and volts don't exceed the mppt specs)?
Just trying to figure out why they don't seem to produce as much power as I thought they would.

 

[Andrewr05]

It depends on how you have it setup.

In order for us to help you, you would need to tell us all of the information on the back of your solar panels as well as what the input specifications are on your inverter.

Vmp, Isc, Voc etc for solar panels and voltage range and amperage limit of the inverter.

 

[bikerider4818]

 

[Andrewr05]

It looks like according to calculations each string of 5 should be making at least 2200W on average.

 

[pollenface]

12-17% on a cloudy day is typical.

I get about 4% on a rainy day.

Maybe 75-95% on a clear sunny day with panels positioned optimally, although only for short periods during bulk phase.

I never ever get 100% or more than 100% output

 

[GXMnow]

The front side of the panels are doing most of the work. The 400 watt rating is at STC (Standard Test Conditions are 1,000 watts of light on every square meter of the panel while the panel is at 25 degrees C (78 F)

In the real world, we rarely will ever see that. Today, we had some clouds moving by, so my maximum power only hit about 68% of rated power. On very good days, I will get to about 80%. And on rare very sunny but col days, with some light wind to cool the panels, they get near 90% of STC rated power. My 300 watt panels never topped 205 watts today.

On a cloudy day, they will do much worse still. Just a few days ago, I saw the output drop under 10% of STC power just after noon as clouds rolled in.

And don't forget, the panels only make ther maximum power when the sun is directly over them. The power output goes in a "Bell Curve" as it ramps up n the morning, rounds over the top as it passes solar noon, and then ramps back down to zero again.

As for the "Bifacial gain"... You will only really get over the front panel rating if there is a surface the can reflect a lot of light onto the back side of the panels. One place they work is on an elevated ground mount where the sun can reflect off the ground and hit the back side. Snow on the ground can really make that work. My main panels are just mounted 8 inches above my dark shingled roof. There is no light reflect up under the panels.

 

[kmin]

Would it make any difference to have the two arrays joined in parallel with only one line going to the inverter (assuming the amps and volts don't exceed the mppt specs)?

You would go over max usable current 20A vs 17A.
Anyway, max 2500W looks too low to me, I would expect 3000+ consistently.

 

[pollenface]

I never ever get 100% or more than 100% output

I stand corrected. I once got 396w from an old crusty 380w array

 

[shadowmaker]

My bifacials produce only 75-80% of their nominal power (front side rated 700W) with nice sunny summer day and +25C. In spring with fresh snow and -30C they make ~130%. My panels are vertically installed so they suffer when sun is high in the sky (though optimal tilt for summer up here is ~55-60 degrees).

I think ~2500W out of 4kWp is little low, but it depends how hot environment and if there's dust, bird droppings, shadows, etc. over panels.

I have them set facing mostly south

Is your array curved or something or do you mean that both straight line arrays are facing south(ish)?

 

[kmin]

My bifacials produce only 75-80% of their nominal power (front side rated 700W) with nice sunny summer day and +25C. In spring with fresh snow and -30C they make ~130%. My panels are vertically installed so they suffer when sun is high in the sky (though optimal tilt for summer up here is ~55-60 degrees).

I think ~2500W out of 4kWp is little low, but it depends how hot environment and if there's dust, bird droppings, shadows, etc. over panels.


Is your array curved or something or do you mean that both straight line arrays are facing south(ish)?

For curiosity, how many hours of production you get per day in the middle of summer, around juhannus?

 

[shadowmaker]

For curiosity, how many hours of production you get per day in the middle of summer, around juhannus?

I get more than 10% nominal (>4kW) from 5.30-22.20 so almost 17 hours (usually getting around 270-300kWh on a good day). The field around my array is fairly big, but there are distant trees killing my production too early in the evening and too late in the morning. I designed my setup for the winter and snow, but there can be weeks without sun then. Worst production day was around Xmas with only 2kWh. That's just sad...

 

[kmin]

I get more than 10% nominal (>4kW) from 5.30-22.20 so almost 17 hours (usually getting around 270-300kWh on a good day). The field around my array is fairly big, but there are distant trees killing my production too early in the evening and too late in the morning. I designed my setup for the winter and snow, but there can be weeks without sun then. Worst production day was around Xmas with only 2kWh. That's just sad...

What a delusion! Damn trees. I was hoping some ridiculous 20+ hours per day..

 

[GXMnow]

I have a 4,800 watt array with Enphase micro inverters in Southern California. These are 5 year old single sided panels. In early May, on a clear day, I start to get usable power at 6:15 am. It tops 500 watts before 7:45 am. Due to my panels being turned 20 degree west, my "Solar Noon" comes at about 1:00 PM where I do clip my inverters at 3,900 watts. After that, the power starts rolling back down and falls under 500 watts again around 6:45 pm. That puts me over 500 watts for 11 hours a day. It's over 3,000 watts from 10:45 to 3:45 or 5 hours. The time will still get a little longer later in summer, but as the panels get hot, my total daily production is actually a little less. On a good spring day, I can produce over 30 KWHs in a day. In th summer, it falls to 27 KWHS, and in winter, the average is probably just 13 KWHs. Of course, a few cloudy days have knocked it down to just 1 KWH a few times.