2600 Watts Seems Wrong – Expert Help Sought

[LLLL]

My system is up and running for a few days and at mid-day, with full sun, and a clear sky, I’m seeing the inverter reading of about 2600 watts input from 4000 watts of solar panels. Below are more details. Your thoughts would be greatly appreciated.



Growatt SPF 3000TL LVM-ES-48 Inverter
Max. PV Array Power 4000W
Max. PV Input Current 18A
PV Array MPPT Voltage Range 120Vdc~250Vdc



10 Panels, 400 Watts, 7.59 amps, 48 volts each.
(Used – Solaria, PowerXT-400R-PM)

5 panels in Series – Then 2 strings in Parallel =
15.18 amps, 250 Volts, 4000 watts each


(2)EG4 48volt Batteries

South Facing – no obstructions
Panels are clean
The tilt angle of the panels is 21 degrees
10 gauge wires from Signature Solar

At the time of reading, Inverter says batteries are 70% full

The outside temperature is about 100 degrees Fahrenheit (panels must be at least 180 degrees since my building siding is nearly 150 degrees)

I tested each string of panels with my multi-meter both are producing power equally.

 

[justinjja]

I might have missed it, where are you in the world?

 

[rmaddy]

180ºF means the Voc will only be 83% of what it would be at STC (77ºF). That alone knocks your panels down from 4kW to 3.3kW. The panels are used. Who knows what they would produce in ideal conditions. If the used panels are only giving 80% then that gets you down to about 2.6kW. You also lose a little from panel tilt being a bit off, time of day, and weather. You said clear blue skies but it could be a little hazy or humid and that will reduce insolation a little.

A word of warning. You have a Voc of 240.5V on an SCC that has a max of 250V. Your panels will reach 250V at only 53ºF. I know that's far from the raging 100ºF you have at the moment but if it can ever get down to the low 50s at night where you live then you run the risk of frying your Growatts.

 

[LLLL]

I'm in Northern California, Justinjja.

rmaddy, super the details help. okay so it's looking like with the heat of 100F and used panels the 2600 watts is understandable.
In researching the tilt for summer at my exact location this came up as ideal (they will go up to 31 degrees on October first.
I'm trying to understand the warning ' You have a Voc of 240.5V on an SCC that has a max of 250V. Your panels will reach 250V at only 53ºF.'
I'm not getting the relationship between voltage and temperature. To make it short perhaps; wouldn't the inverter be able to handle the 250v as rated, and perhaps a bit more. Thanks so much!

 

[justinjja]

I can tell you my used 295w panels only do about 2000W out of 3540W rated
My new solarever 445W panels can do 2190W out of 2670W rated
at the same (not ideal) angle and same (Very hot) ambient temperature
In Texas.

 

[LLLL]

Good to know this data, justinjja. Thank you

 

[rmaddy]

I'm trying to understand the warning ' You have a Voc of 240.5V on an SCC that has a max of 250V. Your panels will reach 250V at only 53ºF.'
I'm not getting the relationship between voltage and temperature. To make it short perhaps; wouldn't the inverter be able to handle the 250v as rated, and perhaps a bit more.

The max PV input voltage is the absolute max. Do not exceed, ever. 250V or less. Any more and you risk letting out the magic smoke.

Voc decreases as the temperature goes up (hence your lower performance with a 180ºF panel temperature). Conversely, Voc increases as the temperature goes down. The panel specs are given for STC (standard test conditions). Those include being at 25ºC/77ºF. So the 48.1Voc is only true at 77ºF (and a few other "only seen in the test lab" conditions).

Based on the specs of your panels the Voc of your array will creep up to 250V at about 53ºF. This is because you are now 24ºF below the STC conditions the 48.1V applies to. At 53ºF the Voc will be 50.0V (x 5 = 250.0V).

 

[syclonedriver]

Anytime my panels are producing more than half their rating I'm happy. I expect a normal maximum output of about 75% of the panel rating, I have seen this with many different panels.

I currently have two Growatts and 12 * 365 watt panels. I currently have 22 AGM batteries, used take outs free to me. I used to have a much smaller system on an RV, anything over 50% production was great.

 

[LLLL]

The max PV input voltage is the absolute max. Do not exceed, ever. 250V or less. Any more and you risk letting out the magic smoke.

Voc decreases as the temperature goes up (hence your lower performance with a 180ºF panel temperature). Conversely, Voc increases as the temperature goes down. The panel specs are given for STC (standard test conditions). Those include being at 25ºC/77ºF. So the 48.1Voc is only true at 77ºF (and a few other "only seen in the test lab" conditions).

Based on the specs of your panels the Voc of your array will creep up to 250V at about 53ºF. This is because you are now 24ºF below the STC conditions the 48.1V applies to. At 53ºF the Voc will be 50.0V (x 5 = 250.0V).

Interesting... Got it, thanks!

 

[Token Civilian]

This thread is a perfect segue into a question I have.

I just got a new solar generator set up. I had the 400 watts of new "briefcase" type panels set up out in the full summer sun, clear skies, faced near perfect to the 1 pm daylight savings sun (so about as good as it gets). It was about 80-85F ambient. The best output I was getting was right at 300 watts. The panels aluminum frames were quite warm to the touch, not enough to burn the hands, but still very warm.

Is this "less than full rated" output to be expected in summer, warm ambient, conditions due to the temperature effects noted above?

From the above discussion of "STC" it would seem that I'd only get maximum output when ambient temperature was quite a bit less, so that the panels were quite a bit cooler. I'm wanting to max out my input, given expected "knockdowns" in performance, but don't want to go over the top in buying more panels that necessary. Thanks in advance for your insights.
ETA: I'm new to the whole solar thing, so trying to get a feel for what is normal and what is abnormal.

 

[justinjja]

I'm pretty sure STC temp is actually the Cell temperature not ambient temp,
So in the real world it basically never happens.

It may be cooler outside of summer, but it's cooler because you are getting less sunlight, so still not going to hit stc.

 

[justinjja]

Some panels give you NOCT which is a more realistic rating.

 

[rmaddy]

It may be cooler outside of summer, but it's cooler because you are getting less sunlight, so still not going to hit stc.

You can still achieve high wattage in the winter if the panel angle is adjusted as needed. You just get that for a shorter period of time each day.

 

[Lt.Dan]

Plain and simple, dont EVER expect to get the panels rated output. They test these panels under extremely specific circumstances that you will almost NEVER see in the real world. 75-80% is very typical of what you will actually see of even a brand new panel, in perfect conditions, at the perfect angle relative to the sun, etc etc etc...

There are people I see all the time claiming they are getting 100% or more, and I find it really hard to believe, but I'm a skeptic.

 

[tomy2]

Plain and simple, dont EVER expect to get the panels rated output. They test these panels under extremely specific circumstances that you will almost NEVER see in the real world. 75-80% is very typical of what you will actually see of even a brand new panel, in perfect conditions, at the perfect angle relative to the sun, etc etc etc...

There are people I see all the time claiming they are getting 100% or more, and I find it really hard to believe, but I'm a skeptic.

I hear ya, have new Solarever panels that put out 80% max of the rated wattage and more like 70% most the day. At first I thought that I got ripped, then read some posts like this. I'll be curious to see what they do in winter, when it is a lot colder and the angle will be closer to right.

 

[Xhumeka]

There are people I see all the time claiming they are getting 100% or more, and I find it really hard to believe, but I'm a skeptic.

I wonder how much smog/smoke/haze/pollution factors into the equation... I'm on the other side of the fence than you, because I have personally seen dozens of 10 year old panels produce 95-100 percent of their ratings on clear sunny days with the right angling.

 

[tomy2]

I might have missed it, where are you in the world?

My system is very similiar, same inverter, same batteries and 10 panels {370watt

My system is up and running for a few days and at mid-day, with full sun, and a clear sky, I’m seeing the inverter reading of about 2600 watts input from 4000 watts of solar panels. Below are more details. Your thoughts would be greatly appreciated.



Growatt SPF 3000TL LVM-ES-48 Inverter
Max. PV Array Power 4000W
Max. PV Input Current 18A
PV Array MPPT Voltage Range 120Vdc~250Vdc



10 Panels, 400 Watts, 7.59 amps, 48 volts each.
(Used – Solaria, PowerXT-400R-PM)

5 panels in Series – Then 2 strings in Parallel =
15.18 amps, 250 Volts, 4000 watts each


(2)EG4 48volt Batteries

South Facing – no obstructions
Panels are clean
The tilt angle of the panels is 21 degrees
10 gauge wires from Signature Solar

At the time of reading, Inverter says batteries are 70% full

The outside temperature is about 100 degrees Fahrenheit (panels must be at least 180 degrees since my building siding is nearly 150 degrees)

I tested each string of panels with my multi-meter both are producing power equally.

View attachment 104109View attachment 104110

My setup is almost identical, except I use the new EG4 3000 AIO. what is that top picture? Also why do you not run all your panels in series? Like your hippie looking homestead.

 

[tomy2]

I wonder how much smog/smoke/haze/pollution factors into the equation... I'm on the other side of the fence than you, because I have personally seen dozens of 10 year old panels produce 95-100 percent of their ratings on clear sunny days with the right angling.

maybe it's because yyou are in Canada where it is colder and the air is cleaner!

 

[12VoltInstalls]

You can still achieve high wattage in the winter if the panel angle is adjusted as needed. You just get that for a shorter period of time each day.

Plain and simple, dont EVER expect to get the panels rated output. They test these panels under extremely specific circumstances that you will almost NEVER see in the real world

Well I got some pretty stinkin’ awesome numbers last winter with my measly 800W with the SCC putting out 42+ amps at 14.4V eith 400W SE and 400W SW which I thought was fantabulous. 300W in hot conditions seems decent to me?‍from 400W

 

[Standahl]

I've got 10 panels on my garage roof, and I believe the system is supposed to be 2kw (they've been up there for 14 years and I don't remember the details). I remember getting about 1600w on a good summer day, then turning the hose on them and watching the output go up to 2100w or more as they cooled.