Separate panel 80 ft away from others

[Julian-Indaiatuba]

I have ten 330W panels in series about 100ft from my inverter on a 48V system. There’s another 330W panel I used to use for another smaller 24V system, which now is no longer in use. This panel is about 20ft from my inverter.
My inverter supports up to 500V VDC, so I was thinking adding the other panel. Could I just connect it in series with the others, even if it’s about 80ft away, or do I need to place it as close to the others as possible?
I would be so much easier if I could leave the single panel in place, as it is fixed to te roof, and I don´t really have any extra space where the other 10 panels are mounted.

Specs of all panels:

Nominal Max. Power (Pmax) 330 W

Opt. Operating Voltage (Vmp) 32.2 V

Opt. Operating Current (Imp) 10.24 A

Open Circuit Voltage (Voc) 39.2 V

Short Circuit Current (Isc) 10.82 A


Thanks in advance for any suggestions.

 

[sunshine_eggo]

11*39.2 = 431.2V

At -15°C, you'll hit 500V.

If you're just talking about diverting one of the cables to capture that panel in the string, I think that's fine. It sounds like you're just adding about 20' to the string wiring. You're just adding resistance, but at 400V+, it's probably going to be difficult to measure the additional losses.

 

[Julian-Indaiatuba]

Thank you for replying so quickly. I don´t think I´m too worried about those small losses if I can add about 10% to my array with a panel that is otherwise being useless.
I will connect the panel tomorrow then, and see if my production improves a little.
The temperature shouldn´t be a problem as I live in the tropics, and we seldomly go below 12C in the winter.
Thanks again.

 

[SamDeleted]

Does the single panel get shade at a different time of the day to the main array

Is it on a different angle or orientation?

If so, if placed in series it could effect the production of the whole array

You could actually loose more than you gain

 

[sunshine_eggo]

Does the single panel get shade at a different time of the day to the main array

Is it on a different angle or orientation?

If so, if placed in series it could effect the production of the whole array

You could actually loose more than you gain

This is an excellent point.

 

[OffGridInTheCity]

I have a 'split 3s' string in my system. 2 panels on the ground array and 1 panel over on a gazebo

This adds an extra 60ft on one of the strings compared to the others combined at the Charge controller - and honestly I don't notice any issues other than the gazebo panel (and thus that 3s string) is shaded more than the other strings on the ground array.

 

[Julian-Indaiatuba]

This is an excellent point.

Does the single panel get shade at a different time of the day to the main array

Is it on a different angle or orientation?

If so, if placed in series it could effect the production of the whole array

You could actually loose more than you gain

Does the single panel get shade at a different time of the day to the main array

Is it on a different angle or orientation?

If so, if placed in series it could effect the production of the whole array

You could actually loose more than you gain

Thank you for your input.
Yes, the lone panel is at a slightly different angle, but receives sun from the same time as the other panels and is never shaded.
Our house is exactly on the tropic of Capricorn, so especially in the summer, the sun is straight above us.
Could I really loose more than I gain in this situation?

 

[Julian-Indaiatuba]

I have a 'split 3s' string in my system. 2 panels on the ground array and 1 panel over on a gazebo
View attachment 152691
This adds an extra 60ft on one of the strings compared to the others combined at the Charge controller - and honestly I don't notice any issues other than the gazebo panel (and thus that 3s string) is shaded more than the other strings on the ground array.

Thank you! This too is very useful information.
I think I will give it a try.

 

[sunshine_eggo]

Thank you for your input.
Yes, the lone panel is at a slightly different angle, but receives sun from the same time as the other panels and is never shaded.
Our house is exactly on the tropic of Capricorn, so especially in the summer, the sun is straight above us.
Could I really loose more than I gain in this situation?

How much is "slightly"?

"slightly" may not have much effect, but when it's added to the string, if it's the lowest current panel, it will force all other panels down to its current. If it's current is 10% lower, it will force the rest of the array to produce 10% less - that would negate any gains of the 11th panel.

 

[Julian-Indaiatuba]

How much is "slightly"?

"slightly" may not have much effect, but when it's added to the string, if it's the lowest current panel, it will force all other panels down to its current. If it's current is 10% lower, it will force the rest of the array to produce 10% less - that would negate any gains of the 11th panel.

Thank you again for your input.
All 10 panels are mounted at a 23°, as is the lone panel. The 10 panels are facing north, whereas the other panel is facing a bit more north-west.
Do you feel this really could be an issue?

 

[SamDeleted]

Our house is exactly on the tropic of Capricorn, so especially in the summer, the sun is straight above us.
Could I really loose more than I gain in this situation?

I think being so close to the equator it should be no probs at all , bet you get great solar production!

 

[Julian-Indaiatuba]

I think being so close to the equator it should be no probs at all , bet you get great solar production!

I don´t think I can complain. My ten 330W panels generate about 15 or 16 kW on a good summer´s day, and around 12kW during the winter.

 

[sunshine_eggo]

Thank you again for your input.
All 10 panels are mounted at a 23°, as is the lone panel. The 10 panels are facing north, whereas the other panel is facing a bit more north-west.
Do you feel this really could be an issue?

You can try it and see.

 

[ksmithaz1]

10*330 = 3300W. If you are talking on a given say 10 hour day 10*3300 = 33000wh/day (33KWH). So I'm curious as to what your 14K number is trying to convey?

 

[sunshine_eggo]

10*330 = 3300W. If you are talking on a given say 10 hour day 10*3300 = 33000wh/day (33KWH). So I'm curious as to what your 14K number is trying to convey?

I hope you know it works nothing like this at all. 3300W will do well to produce 16.5kWh/day on average.

Generally speaking, a 3300W array only produces 3300W array in perfect conditions at high noon when the panel is perfectly parallel to the sun. It will produce less at all other times. There are outlier cases where panels can produce MORE than rated, but that's not part of this discussion.

While Phoenix sun is great, the heat is so brutal, the panels won't actually achieve rated power in most cases as the hot cells output lower voltage. Ratings are for when the CELLS are at 25°C (77°F). In Phoenix sun, they're likely to be 50-60°C, which is going to knock 10-15% off their rating due to lower operating voltage.

Here's typical numbers for Phoenix:



The above numbers mean that you will get the equivalent of 6.74 hours of full power output with constant exposure from sunrise to sunset, so that 3300W array on your roof tilted 33° from horizonal facing due South will produce (approximately):

3.3kW * 6.74h = 22.2kWh - nowhere near 33kWh

 

[ksmithaz1]

I was just locking for clarity on the number as it was simply not clear, but in a sunny area I would hope to get closer 20 or so kw.er.hours/day. But hours were not mentioned, and I would not expect to see 14kw of output from a 3kw array, so for daily kwH total output that seemed a little lower than I would expect in a sunny climate. Of course panels lose a few percent every year, so 3.3kw slips to 3kw after a year or so, . . .

 

[Julian-Indaiatuba]

I hope you know it works nothing like this at all. 3300W will do well to produce 16.5kWh/day on average.

Generally speaking, a 3300W array only produces 3300W array in perfect conditions at high noon when the panel is perfectly parallel to the sun. It will produce less at all other times. There are outlier cases where panels can produce MORE than rated, but that's not part of this discussion.

While Phoenix sun is great, the heat is so brutal, the panels won't actually achieve rated power in most cases as the hot cells output lower voltage. Ratings are for when the CELLS are at 25°C (77°F). In Phoenix sun, they're likely to be 50-60°C, which is going to knock 10-15% off their rating due to lower operating voltage.

Here's typical numbers for Phoenix:

View attachment 152931

The above numbers mean that you will get the equivalent of 6.74 hours of full power output with constant exposure from sunrise to sunset, so that 3300W array on your roof tilted 33° from horizonal facing due South will produce (approximately):

3.3kW * 6.74h = 22.2kWh - nowhere near 33kWh

I was just locking for clarity on the number as it was simply not clear, but in a sunny area I would hope to get closer 20 or so kw.er.hours/day. But hours were not mentioned, and I would not expect to see 14kw of output from a 3kw array, so for daily kwH total output that seemed a little lower than I would expect in a sunny climate. Of course panels lose a few percent every year, so 3.3kw slips to 3kw after a year or so, . . .

Thanks again fo all your replies.
To me the 16 kW a day my 10 panels produce in the summer seems perfectly normal.
Like mentioned above, the conditions have to be perfect to achieve 330W per panel per hour, and this is theorectically only possible 5 to 6 hours a day, often more like 3 or 4 hours.
Allthough where I live, Indaiatuba-Brazil, we have scorching sun, the daily tempertures often around 35°C, the panels get too hot to perform as well as it´s label specifications.

 

[RCinFLA]

The current from the string of panels will be near what the Imp current is from the lowest current output panel is. Current from a panel is primarily its illumination level.

If the added panel is off angle from others, it will have periods of day where it produces less current and reduce the output of the other panels.

To achieve the same series string current, the off angle panel will run slightly below Vmp yielding a slight increase in Imp. The other ten panels will run slightly higher Vmp to reduce their current output to match the current output of the lower current output single panel.

Compromising ten panels' output for one panel is usually a losing proposition.

 

[sunshine_eggo]

I was just locking for clarity on the number as it was simply not clear, but in a sunny area I would hope to get closer 20 or so kw.er.hours/day.
But hours were not mentioned, and I would not expect to see 14kw of output from a 3kw array, so for daily kwH total output that seemed a little lower than I would expect in a sunny climate.

On average considering all factors, 5 solar hours per day is a good estimate for rough calculations for spring through fall. As I already demonstrated above 3.3kWh * 5h = 16.5kWh - pretty close to 14kWh and dramatically different than your 33kWh/day number.

It's evident you don't have a grasp on the concept as there isn't a location on Earth that would yield 33kWh from a 3.3kW fixed array.

Furthermore, I have given you numbers that show even at your location a 3.3kW array will only yield 3.3kW * 4.75h = 15.7kWh in December.

Please use this as a learning experience.

Of course panels lose a few percent every year, so 3.3kw slips to 3kw after a year or so, . . .

No. This is completely wrong. Most panels deteriorate 10-20% over 20-30 years. 10% in a year is absurd.

You indicate 3%/year but then knock 10% off for the first year?

My array is 4 years old, and I have seen no signs of deterioration. In spring and fall where tilt is optimal and temperatures are favorable, my array regularly exceeds rated due to "perfect" conditions including getting more than 1000W/m^2 due to elevation.

 

[ksmithaz1]

I love being completely wrong... when making off the cuff remarks. Makes me go try things... The panels I have say they lose 1% a year. Percentage losses could be compounded, or maybe not, it doesn't really say, but back to the 3300W panels. My 455Wx32 panels can technically produce 14560 watts. So using the sunshine charts that would net me at best 87360 (14560*6). If my inverters are to be believed, I'm pulling in around 98KWH/day, but I've never seen output significantly above 12KW. So in a sunny area I would hope 3300 watts of panels would get me closer to 18KWH than 14KWH/day, but I am in Arizona where we get ridiculous sun. I wonder how much actual loss is there as you move north, or things like humidity and such. Living in a wooded area for example is going to kill your morning and afternoon output unless you have the panels above the treeline.