distance between panels in a series array

[Scraggs]

Hi all
I am starting to get everything setup for my off grid setup, but would just like some help if possible.
I will be having 2 arrays with 12 x 390w panels connected to a Fronius 8.2 primo. these will be wired in series but due to some shade issues that have come into play since the setups inception on the site some of the panels that make up the array will now have to be spread out.
The panels will be on frames that hold 3 panels, some are right next to each other but some will be 5-6 metres away from the next in the array. is this likely to cause problems ? I know if they were in parallel the wires between panels should ideally be the same length but not sure it is so critical in series.
Any advice greatly appreciated.

 

[sunshine_eggo]

Hi all
I am starting to get everything setup for my off grid setup, but would just like some help if possible.
I will be having 2 arrays with 12 x 390w panels connected to a Fronius 8.2 primo. these will be wired in series but due to some shade issues that have come into play since the setups inception on the site some of the panels that make up the array will now have to be spread out.
The panels will be on frames that hold 3 panels, some are right next to each other but some will be 5-6 metres away from the next in the array. is this likely to cause problems ? I know if they were in parallel the wires between panels should ideally be the same length but not sure it is so critical in series.
Any advice greatly appreciated.

No.

 

[Symbioquine]

A little more verbosely stated; "it's not likely to cause significant problems."

With batteries, you want the length of the cables to be similar because imbalances can persist in the long term state of charge for the batteries/cells - which can cause undue wear on some of the batteries/cells and eventually an early death for the batteries.

On the other hand, with solar panels the worst case is that the solar panels will produce less power than they optimally could.

If you're worried, you can reason through what's going to happen with longer than necessary or mismatched connections to solar panels (or strings of solar panels) by extrapolating from what happens if you attach mismatched solar panels together. To do this, you can add in the voltage drop from the wire associated with each panel or string of panels and see how that affects your maximum power point numbers from your panels. (This won't be perfect, but I think it's a pretty good starting point for checking whether a configuration has a chance of working reasonably.)

For example, if you were attaching two nominal 100 watt panels (Vmp=17.9v, Imp=5.72A) in parallel with one panel 10 feet away and another panel 100 feet away using 12 guage wire, we could guess that the voltage of the 100 foot away panel would drag the parallel voltage at the charge controller down to about 15.6 volts. So instead of getting around 200 watts for the panels in parallel, you'd get only about 89% of that in the best case;

15.6v * (2 * 5.72A) = ~178.5 watts

 

[Scraggs]

No.

Thank you

 

[Scraggs]

A little more verbosely stated; "it's not likely to cause significant problems."

With batteries, you want the length of the cables to be similar because imbalances can persist in the long term state of charge for the batteries/cells - which can cause undue wear on some of the batteries/cells and eventually an early death for the batteries.

On the other hand, with solar panels the worst case is that the solar panels will produce less power than they optimally could.

If you're worried, you can reason through what's going to happen with longer than necessary or mismatched connections to solar panels (or strings of solar panels) by extrapolating from what happens if you attach mismatched solar panels together. To do this, you can add in the voltage drop from the wire associated with each panel or string of panels and see how that affects your maximum power point numbers from your panels. (This won't be perfect, but I think it's a pretty good starting point for checking whether a configuration has a chance of working reasonably.)

For example, if you were attaching two nominal 100 watt panels (Vmp=17.9v, Imp=5.72A) in parallel with one panel 10 feet away and another panel 100 feet away using 12 guage wire, we could guess that the voltage of the 100 foot away panel would drag the parallel voltage at the charge controller down to about 15.6 volts. So instead of getting around 200 watts for the panels in parallel, you'd get only about 89% of that in the best case;

15.6v * (2 * 5.72A) = ~178.5 watts

View attachment 82508

Thank you.
Some very useful information.