Question 3S 2P and pictures of crates

[joeExotic]

Question: I was told it would be better to point the solar panels in different directions. For example, point one to catch the morning sun and point the other facing the other way.

My question is: Can I NOT point one to catch the morning sun and point both of them to catch the afternoon sun?

Which one would generate more energy?

My setup is 3S 2P. All 100w panels. 40A charge controller Li. 1,000W psw inverter. 360AH LFP 12V Battery.

 

[Bud Martin]

Question: I was told it would be better to point the solar panels in different directions. For example, point one to catch the morning sun and point the other facing the other way.

My question is: Can I NOT point one to catch the morning sun and point both of them to catch the afternoon sun?

Which one would generate more energy?

My setup is 3S 2P. All 100w panels. 40A charge controller Li. 1,000W pew inverter. 360AH LFP 12V Battery.

You can easily do the experiment and find out and record the result, that will be real test for your setup at your location.

 

[joeExotic]

You can easily do the experiment and find out and record the result, that will be real test for your setup at your location.

I guess I am just concerned by pointing them both this way to watch the afternoon sun that it will be damaging to my set up?

 

[Bud Martin]

I guess I am just concerned by pointing them both this way to watch the afternoon sun that it will be damaging to my set up?

Damaged as in how?

 

[joeExotic]

I guess my charge controller is 40 A so if all 6 panels are getting direct sun in the afternoon will the charge controller be able to handle it?

 

[Bud Martin]

The load pulls current from the source, the PV Panels do not push current through the load, the load will pull current as needed up to the charger maximum current. I.E. you have 600A cranking amp car battery in your car, when you turn on your car radio, is the battery going to force 600A into your your car radio?
The parameter that you need to watch out for is the max PV Voltage, if you exceed that, it will damage the charger controller. So what is the spec of the panel and the SCC?

 

[joeExotic]

I think the max v this set up of 3S2P will be 60v. So I think I will be fine?

 

[Bud Martin]

I think the max v this set up of 3S2P will be 60v. So I think I will be fine?

It will be higher in cold temperature, I usually factor in 15 ~ 20% higher.
What is the max PV input of the SCC, 100V or more?

 

[joeExotic]

Just took a picture. The v on the CC showed 50 earlier just after setting it up to 3S2P. It was a little cloudy out today. Just a little cloudy

 

[Bud Martin]

100V max PV so you are OK.

 

[joeExotic]

I will do what you suggested and monitor it for the next few days. Thank you

 

[Bud Martin]

I will do what you suggested and monitor it for the next few days. Thank you

Great! please provide the result so will have real world data.

 

[joeExotic]

Did not get much around 8 -9 AM it was floating around 2 amps.

At around 10AM was getting around 10amp

Now at noon 12PM getting around 25amps.

I think this will work best for me because I'm not using much early in the morning but by 10AM I have the laptop, monitor, and other small electronics charging.

I didn't like the idea of facing one of them to catch the morning sun because by mid afternoon it would not be getting direct sunlight. I hope I am making the right decision and pointing these panels to catch the afternoon sun.

 

[chrisski]

I have a 3S3P setup with 100 watt panels. One string to the morning sun; one to the noon sun; one to the setting sun. This keeps a constant charge on the system so the battery does not die during the day When I leave it on for 10 hours unattended. The max the SCC can charge is 420 watts. So, in my case with the VIctron SCC 75/15, overpaneling and pointing in different directions has been fine.

 

[joeExotic]

I have a 3S3P setup with 100 watt panels. One string to the morning sun; one to the noon sun; one to the setting sun. This keeps a constant charge on the system so the battery does not die during the day When I leave it on for 10 hours unattended. The max the SCC can charge is 420 watts. So, in my case with the VIctron SCC 75/15, overpaneling and pointing in different directions has been fine.

Do you have to use a fuse for the panels?
I'm hitting 51 v. Not sure if my CC can handle another three 100w panels.

 

[chrisski]

With 3s3p, I have each string with a circuit breaker. I think 10 amps. When I was 3s2p I did not have a breaker.

I am always tweaking the portable panels so the breaker comes in handy to see what string is bad. Usually ends up being user error, like a cable not plugged in, but other times it’s something like a screw has backed off.

 

[sunshine]

My setup is 3S 2P.

Why not 2S 3P ....if that is the correct designation?? in E, N, W position ( N because Australia).
Q (not for the OP)- What is best for the MPP algorithym?

 

[MisterSandals]

What is best for the MPP algorithym?

I'd first look at the MPPT range of any SCC as that is the sweet spot for input voltage. It used to be folks recommended about 80% of max input voltage but now i think the consensus is that closer to battery voltage is better (but well within the MPPT range).
Putting 3 strings in parallel will spread the charging over a larger portion of the day with lower working volts and amps. Lower amps is easier to wire and easier on equipment. Voltage is a little different in that a 2S string will have a lower voltage than a 3S string and on cloudy days or low light hours, its likely that they won't produce a high enough voltage for an MPPT to start charging (usually battery voltage and about 5V).
Having 3 strings in parallel requires that each string be fused.

So which is best? It depends. I tend to like more in series because it means lower amps.
But i also really like spreading charging over a longer period as you mentioned so maybe i'd favor that over 3S.

 

[joeExotic]

Got a total of 135ah today. Is that normal? Good?

 

[MisterSandals]

Got a total of 135ah today. Is that normal? Good?

100W x 6 = 600W (at 100% efficiency)
600W / 12.8V battery = 46.9A
135Ah / 46.9A = 2.9h of quality sun

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Or considering you got 5h of quality sun
135Ah / 5h = 27A charging (57% of maximum under ideal conditions)

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600W x .57 efficiency = 342W (still assuming this is spread over 5h)

Seems more than reasonable for mid to high latitudes for this time of year.