Series parallel help

[OMG]

Thank you to everyone who replied to my last question! In Wills book for the 400 watt 12 volt system he has 2 100 watt panels in series and then he parallels 2 of them together. How is this better than 4 100 watt 12 volt panels in parallel? I am learnin!

 

[cs1234]

Thank you to everyone who replied to my last question! In Wills book for the 400 watt 12 volt system he has 2 100 watt panels in series and then he parallels 2 of them together. How is this better than 4 100 watt 12 volt panels in parallel? I am learnin!

It's not necessarily better, it depends on what the charge controller supports.

Charge controllers have input voltage limitations and maximum amounts of amperage they will willingly pull down. There are also cabling concerns, higher voltage strings in series have lower losses and can use less cable thickness, but the controller has to support those higher voltages or it goes bye bye when it sees the higher voltage.

 

[OMG]

It's not necessarily better, it depends on what the charge controller supports.

Charge controllers have input voltage limitations and maximum amounts of amperage they will willingly pull down. There are also cabling concerns, higher voltage strings in series have lower losses and can use less cable thickness, but the controller has to support those higher voltages or it goes bye bye when it sees the higher voltage.

I have a 40 mppt that will accept 100 volts and 550 watts at 12 volts. And I’m using 4 100 watt 12volt panels in parallel so I really can’t get too much more from it. Thank you

 

[cs1234]

I have a 40 mppt that will accept 100 volts and 550 watts at 12 volts. And I’m using 4 100 watt 12volt panels in parallel so I really can’t get too much more from it. Thank you

If you are really running the panels in parallel, you might actually be able to get slightly more out of your panels by being in serial instead.. due to lower voltage drop across the lines from a higher starting voltage and lower amperage. You also wouldn't need the four fuses / combiner box you should be running if you have four panels in parallel.

What is the VOC on your solar panels? It's on the sticker on the back of them.

 

[time2roll]

I have a 40 mppt that will accept 100 volts and 550 watts at 12 volts. And I’m using 4 100 watt 12volt panels in parallel so I really can’t get too much more from it. Thank you

I would go series for simplicity. Careful of the higher voltage.

Generally MPPT can be overdriven some as they will self limit amps at the rating if by some miracle the panels actually all produce the max. Say 6x 100 watt panels with 3 series 2 strings parallel.

 

[OMG]

If you are really running the panels in parallel, you might actually be able to get slightly more out of your panels by being in serial instead.. due to lower voltage drop across the lines from a higher starting voltage and lower amperage. You also wouldn't need the four fuses / combiner box you should be running if you have four panels in parallel.

What is the VOC on your solar panels? It's on the sticker on the back of them.

I’m showing open circuit voltage of 24.3 On the sticker. I opted for a 4 to 1 adapter instead of a combiner box. I do have a 6 string combiner but not using it currently. My plan is to ad a parallel array facing east to my array facing south. But I’m still figuring things out..

 

[OMG]

I would go series for simplicity. Careful of the higher voltage.

Generally MPPT can be overdriven some as they will self limit amps at the rating if by some miracle the panels actually all produce the max. Say 6x 100 watt panels with 3 series 2 strings parallel.

Thank you for replying. What would the output for something like that look like? This is where I really have trouble.

 

[cs1234]

I’m showing open circuit voltage of 24.3 On the sticker. I opted for a 4 to 1 adapter instead of a combiner box. I do have a 6 string combiner but not using it currently. My plan is to ad a parallel array facing east to my array facing south. But I’m still figuring things out..

Ok, you can't run them in a 4s configuration, because you would end up burning out your inverter by exceeding it's maximum VOC input. But, you would still probably have slightly less loss by running in a 2s2p configuration, and then you wouldn't need fuses or a combiner box for right now.

This would also give you some more leeway for adding another 2 of the panels down the road for a 2s3p configuration, and you could face those panels in some other direction to capture sun at a different time/angle. You would need fuses or a combiner box with fuses once you go back to a 3p or higher parallel array.

 

[time2roll]

Yes appears to be 3 max in series. So with 4 it will be 4p or 2p2s.

 

[time2roll]

Thank you for replying. What would the output for something like that look like? This is where I really have trouble.

Output will be the programmed voltage at 40 amps max. 40 amps at 14 volts is 560 watts needed input. If the battery is low like 12.8, that 400w might yield 31.25 amps tapering to 28amps as the battery voltage rises.

 

[OMG]

Output will be the programmed voltage at 40 amps max. 40 amps at 14 volts is 560 watts needed input. If the battery is low like 12.8, that 400w might yield 31.25 amps tapering to 28amps as the battery voltage rises.

I didn’t think I could get any more than 20 amps total out of my array. The panels are rated at 5 amp.

 

[OMG]

Ok, you can't run them in a 4s configuration, because you would end up burning out your inverter by exceeding it's maximum VOC input. But, you would still probably have slightly less loss by running in a 2s2p configuration, and then you wouldn't need fuses or a combiner box for right now.

This would also give you some more leeway for adding another 2 of the panels down the road for a 2s3p configuration, and you could face those panels in some other direction to capture sun at a different time/angle. You would need fuses or a combiner box with fuses once you go back to a 3p or higher parallel array.

2 series is say 40 volts 5 amps parallel them 40 volts 10 amps add a third 40 volts 15 amps. 4 in parallel is say 20 volts 20 amp. This is what I’m coming up with in a perfect world. And then I was going to duplicate that facing in another direction to add sun hours to the system. I currently have 4 12v 115ah deep cycle lead batteries and will add 2 more for a total of 690ah 8280wh or 4kWh usable. Am I close?

 

[OMG]

2 series is say 40 volts 5 amps parallel them 40 volts 10 amps add a third 40 volts 15 amps. 4 in parallel is say 20 volts 20 amp. This is what I’m coming up with in a perfect world. And then I was going to duplicate that facing in another direction to add sun hours to the system. I currently have 4 12v 115ah deep cycle lead batteries and will add 2 more for a total of 690ah 8280wh or 4kWh usable. Am I close?

Well I hope no reply means I’m getting a grip on things! If not please chime in I’ve been studying hard !

 

[cs1234]

2 series is say 40 volts 5 amps parallel them 40 volts 10 amps add a third 40 volts 15 amps. 4 in parallel is say 20 volts 20 amp. This is what I’m coming up with in a perfect world. And then I was going to duplicate that facing in another direction to add sun hours to the system. I currently have 4 12v 115ah deep cycle lead batteries and will add 2 more for a total of 690ah 8280wh or 4kWh usable. Am I close?

Your numbers are correct. 40 volts at 10 amps is better than 20 volts at 20 amps because of voltage loss over distance.

Your battery numbers are correct, although I've seen things around here about adding additional lead acid batteries into an existing array. Maybe somebody else can chime in about that.

 

[OMG]

Your numbers are correct. 40 volts at 10 amps is better than 20 volts at 20 amps because of voltage loss over distance.

Your battery numbers are correct, although I've seen things around here about adding additional lead acid batteries into an existing array. Maybe somebody else can chime in about that.

I get the higher voltage better now, it helps insure my amps get there. I appreciate your help. Got a lot to learn still but that’s what keeps me going!

 

[cs1234]

I get the higher voltage better now, it helps insure my amps get there. I appreciate your help. Got a lot to learn still but that’s what keeps me going!

Amps are what determine cable thickness requirement. Generally speaking, 10 amps is 10 amps, whether it's at 1 volt or 100 volts. The more voltage at a given amperage, the more watts to run your stuff / charge your batteries.

If you have 1000 watts to get across a cable, you could send it at 100volts at 10 amps and need a tiny cable, or 10volts at 100amps and need a much thicker cable.

 

[OMG]

Amps are what determine cable thickness requirement. Generally speaking, 10 amps is 10 amps, whether it's at 1 volt or 100 volts. The more voltage at a given amperage, the more watts to run your stuff / charge your batteries.

If you have 1000 watts to get across a cable, you could send it at 100volts at 10 amps and need a tiny cable, or 10volts at 100amps and need a much thicker cable.

Yes I understand that. But I don’t get what happens at the charge control because if it drops my voltage what happens to my amps then? I am going to change my array to 2s2p so I can see what the difference is.

 

[oneshotjon]

I'm interested to know what you discovered. I have a similar system on my RV ...that never goes anywhere.

 

[OMG]

I'm interested to know what you discovered. I have a similar system on my RV ...that never goes anywhere.

Hello, Sorry for the delay! With 2S2P Aside from the obvious double volts and half the amps. I don’t believe my batteries are charging as fast as a 4P array and I feel as though I’m not able to keep things running as well as with the 4P array. I am a novice so any comments are welcome.

 

[OMG]

Hello, Sorry for the delay! With 2S2P Aside from the obvious double volts and half the amps. I don’t believe my batteries are charging as fast as a 4P array and I feel as though I’m not able to keep things running as well as with the 4P array. I am a novice so any comments are welcome.

So what are you using ? 4P or 2S2P