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solar..parallel Vs series parallel


jenevers

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Parallel - shading only effects one panel (some more expensive panels this isn’t an issue).   Need thicker cables as you have more current and less voltage.

 

Series - Increased voltage so thinner cables and less voltage drop to the controller.  If one panel shaded it will drop the output of all panels.

Edited by Robbo
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Didn't you ask this question last Friday? That topic sort of degenerated in to a discussion of electric shock risk.

 

To answer it, can you tell us how many panels you have and what their open circuit maximum output voltage is? Also, what solar controller you are planning to use. Preferably links to the data sheets. From there we can work out what series/parallel layouts are even possible for your situation, before going in to potential advantages/disadvantages. Short answer is that there isn't a cut and dried answer. Each wiring scheme has advantages and disadvantages, but in the big scheme of things they don't matter much.

 

Jen

 

Edited by Jen-in-Wellies
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I would go two in series, in parallel with the other two in series, that way you get a bit of both. If you have all four in series there is a good chance of some section being in the shade. I think as I've described they can still all go into one controller (subject to the controllers ratings) - it's what I'm doing when I get my second pair anyway.

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6 hours ago, Jen-in-Wellies said:

Didn't you ask this question last Friday? That topic sort of degenerated in to a discussion of electric shock risk.

 

To answer it, can you tell us how many panels you have and what their open circuit maximum output voltage is? Also, what solar controller you are planning to use. Preferably links to the data sheets. From there we can work out what series/parallel layouts are even possible for your situation, before going in to potential advantages/disadvantages. Short answer is that there isn't a cut and dried answer. Each wiring scheme has advantages and disadvantages, but in the big scheme of things they don't matter much.

 

Jen

 

You’re right I did, but didn’t get any diagrams

The set up will be a 40Amp Tracer 4215BN (150 volts max input value)

4 x 110w panels,

open circuit voltage 22v

max power voltage 18.6v

max power current 5.93A

 

Hope someone can suggest a layout.

 

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5 minutes ago, jenevers said:

You’re right I did, but didn’t get any diagrams

The set up will be a 40Amp Tracer 4215BN (150 volts max input value)

4 x 110w panels,

open circuit voltage 22v

max power voltage 18.6v

max power current 5.93A

 

Hope someone can suggest a layout.

 

I'd go for Series as it gives a better voltage output in 'low-light' (Autumn / Winter / Spring)

 

 

Do you need a wiring diagram for series connections ?

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25 minutes ago, jenevers said:

You’re right I did, but didn’t get any diagrams

The set up will be a 40Amp Tracer 4215BN (150 volts max input value)

4 x 110w panels,

open circuit voltage 22v

max power voltage 18.6v

max power current 5.93A

 

Hope someone can suggest a layout.

 

Does your boat spend most of its time at a mooring with no shade and no land line? If so, then series, as @Alan de Enfield suggests. If there is likely to be shading during part of the day, or you move around a lot, then series-parallel as @Loddon says.

 

Jen

 

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1 hour ago, Alan de Enfield said:

I'd go for Series as it gives a better voltage output in 'low-light' (Autumn / Winter / Spring)

 

 

Do you need a wiring diagram for series connections ?

Not for series thanks but, as I cruise mainly in summer, low light isn’t a problem, so I’m going for series/parallel.

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Series-Parallel wiring. How I'd do it.

The isolation switch between the panels and the controller is important on some models to prevent damage to the controller that can be caused if the batteries are disconnected and they are still getting solar in. Not essential, but easier than pulling the correct plugs out of the panels. Fuse between the controller and the batteries to safeguard the wiring if the controller develops a fault. Wire direct to batteries, bypassing main isolator switch.

 

Jenny

series-parallel.png.05d460fe13a6d071c751be03fc4bdf78.png

 

 

Edited by Jen-in-Wellies
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Not trying to be a clever clogs but for the sake of less electrically competent readers - I know that you know and its just a  drawing thing.

 

The diagram gives the impression the fuse should be close to the controller. This is not so, it needs to be close to the batteries because in case of a short a battery can produce thousand(s) of amps so the cable between battery and fuse would catch fire if shorted where as a short on the controller side would have its current limited by the panels' and controller's ability to supply. AS the cable should be selected to minimise volt drop it is likely to be over size so should not catch fire.

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17 hours ago, Jen-in-Wellies said:

Series-Parallel wiring. How I'd do it.

The isolation switch between the panels and the controller is important on some models to prevent damage to the controller that can be caused if the batteries are disconnected and they are still getting solar in. Not essential, but easier than pulling the correct plugs out of the panels. Fuse between the controller and the batteries to safeguard the wiring if the controller develops a fault. Wire direct to batteries, bypassing main isolator switch.

 

Jenny

series-parallel.png.05d460fe13a6d071c751be03fc4bdf78.png

 

 

Thanks for taking the trouble.?

 

1 hour ago, Tony Brooks said:

Not trying to be a clever clogs but for the sake of less electrically competent readers - I know that you know and its just a  drawing thing.

 

The diagram gives the impression the fuse should be close to the controller. This is not so, it needs to be close to the batteries because in case of a short a battery can produce thousand(s) of amps so the cable between battery and fuse would catch fire if shorted where as a short on the controller side would have its current limited by the panels' and controller's ability to supply. AS the cable should be selected to minimise volt drop it is likely to be over size so should not catch fire.

Ditto?

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1 hour ago, Tony Brooks said:

Not trying to be a clever clogs but for the sake of less electrically competent readers - I know that you know and its just a  drawing thing.

 

The diagram gives the impression the fuse should be close to the controller. This is not so, it needs to be close to the batteries because in case of a short a battery can produce thousand(s) of amps so the cable between battery and fuse would catch fire if shorted where as a short on the controller side would have its current limited by the panels' and controller's ability to supply. AS the cable should be selected to minimise volt drop it is likely to be over size so should not catch fire.

Good point Tony.

Yes, to protect against a short across the batts, rather than a duff controller. In my defence, I ran out of space on the diagram and didn't have enough space for the batteries! ?

 

Jen

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5 minutes ago, Jen-in-Wellies said:

Good point Tony.

Yes, to protect against a short across the batts, rather than a duff controller. In my defence, I ran out of space on the diagram and didn't have enough space for the batteries! ?

 

Jen

Plan Ahea-

d

Edited by TheBiscuits
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2 hours ago, Jen-in-Wellies said:

Good point Tony.

Yes, to protect against a short across the batts, rather than a duff controller. In my defence, I ran out of space on the diagram and didn't have enough space for the batteries! ?

 

Jen

 

Yes, I knew it was something like that and it was in no way intended as a criticism.

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B

On 22/01/2019 at 19:28, Jen-in-Wellies said:

Series-Parallel wiring. How I'd do it.

The isolation switch between the panels and the controller is important on some models to prevent damage to the controller that can be caused if the batteries are disconnected and they are still getting solar in. Not essential, but easier than pulling the correct plugs out of the panels. Fuse between the controller and the batteries to safeguard the wiring if the controller develops a fault. Wire direct to batteries, bypassing main isolator switch.

 

Jenny

series-parallel.png.05d460fe13a6d071c751be03fc4bdf78.png

 

 

Blocking diode advisable?

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Where/why? Most modern panels I have seen contain the requisite diodes. The controller should prevent the battery trying to feed into the panels. Electrcity is valuable ona  boat so you don't want to be wasting it through a diode - especially for charging.

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9 minutes ago, Tony Brooks said:

Where/why? Most modern panels I have seen contain the requisite diodes. The controller should prevent the battery trying to feed into the panels. Electrcity is valuable ona  boat so you don't want to be wasting it through a diode - especially for charging.

Between panels and controller. Suits me fine if I don’t need one, just checking before I order MC4 “Y” plugs. ?

 

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Most panels these days will include both blocking and bypass diodes I believe, although as Tony says, blocking diodes should be uneccessary when used with a controller. 

 

They're usually Schottky diodes for low voltage drop. 

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13 minutes ago, Scholar Gypsy said:

Just been amusing myself designing a waterproof switch (double pole two way) to go on the roof somewhere to switch between series and parallel operation. It won't get built...

For the twice a year it would get used, you might as well just replug the MC4 connectors.  I know a few people that do this to get maximum voltage from the panels over winter and more shade tolerance during the rest of the year.

 

I don't bother changing round, but then I only have one solar panel ... :D

 

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8 minutes ago, TheBiscuits said:

For the twice a year it would get used, you might as well just replug the MC4 connectors.  I know a few people that do this to get maximum voltage from the panels over winter and more shade tolerance during the rest of the year.

 

I don't bother changing round, but then I only have one solar panel ... :D

 

And I've only got two. I will probably remove one, and maybe both, for the main summer cruise, to  create more sunbathing space.

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