Multiple panels

[Jgoodman]

So. I now have 4 more panels that I am looking to hook up for a total of six panels at 355 watts for a total of 2130. What I am looking to find out is 1. How do I hook up all six to feed my charge controller. 2. Do I need to fuse them. Info plate of the panels attached.

 

[MichaelK]

Before these questions can be intelligently answered, we first need to know what controller you have and what your winter low temperatures are like. Also your battery voltage.

Your panels have an open-circuit voltage (Voc) of 46.8V, so their voltages add as you wire them in series. The more economical controllers have a maximal voltage of only 100V, so even just two panels in series would be 46.8V+46.8V= 93.6V. Winter temperatures not even dropping to freezing would already bump the Voc pass 100V.

Let's say you got a Epever 5415AN controller, with a 150V limit. You could wire two panels in series, but not three. With three parallel strings of 2 panels in series (that's 2S3P) you'd get 2130W of power. Charging a 24V system at 25V, that works out to be 2130W/25V = 85.2A, way over the 50A limit of this controller. But, the same controller charging a 48V system, the math would be 2130W/50V = 42.6A, within the capacity of this controller.

How about instead you have the Epever 8420AN controller with a 200V limit. You could safely wire three panels in series to get two parallel strings at 140.4V. At freezing they'd put out ~157V. Use a string calculator like this one with your winter lows to determine what you can wire together.

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With only two parallel strings, no fusing/breakers are required. With three, they are.

So, details matter greatly here.

 

[Jgoodman]

Ok so details are I have a mpt solar lv2424 80amp (pic of model plate included) average winter temps in my area very rarely dip below 32 more typically the average temp would be 35 or slightly higher. I have a 6-1 connection set on order that I plan on using for this set up if it’s feasible and beneficial to do so and will be putting a 2-1 splitter in that to add a wind turbine. Basically wondering if fuses are necessary. And if I am overdoing it

 

[rmaddy]

You need to worry about the absolute coldest temperature you will encounter while using the solar panels. The average temp is irrelevant. One really cold day could send the panel Voc beyond the max input voltage of your SCC and fry it.

Regardless of that concern, 6 of those panels can result in a max battery current of nearly 96A. Your SCC is limited to 80A. The extra amps will be discarded by the SCC. It's just wasted energy and heat.

Matching Michael's earlier comments, given the Voc of the panels and the 145Voc max of your SCC, you can put your panels in at most 2S. 3S will kill the SCC at any temperature below about 5ºC (41ºF).

If you want to use that SCC you should only use four panels in 2S2P. You could add a second, smaller SCC for the other 2 panels.

 

[Bud Martin]

You can do 2S3P, the SCC is smart buck converter power supply, it will only draw/Pull the power from the panel as needed up to the maximum it can use to charge the battery, nothing is wasted. Think of it this way, your AC outlet in your US home can provide power up to 1800W of power, so if you connect 100W bulb into the socket, will you be wasting 1700W of power?
BTW, I have PIP-LV1012-MK 80A SCC and I also over panel my setup by 25% sicne you will never really get the published power spec in real use situation.

 

[rmaddy]

I should clarify my statement that the extra amps will be discarded. That was a poor description. I should have said that 6 of those panels have the potential to produce enough amps that a big enough SCC could generate up to 96A to the battery. With your SCC you are giving up some of that potential.

 

[Jgoodman]

With a 2s3p setup I don’t need fuses? Or is that still a good idea

 

[fazeshift]

With a 2s3p setup I don’t need fuses? Or is that still a good idea

Fuses are always a good idea.

 

[MichaelK]

With a 2s3p setup I don’t need fuses? Or is that still a good idea

It's not just a good idea, it's a code requirement. With three parallel strings, you MUST have each string fused/breakered.

You are right up there at the amp limit of your controller with 6 panels, but you have two options that might let you use them. With three strings of two panels in series, you could mount string 1 facing SE, string 2 facing S, and string 3 facing SW. This will tend to dampen the height of the noon amperage peak, but tend to broaden amperage curve over the course of the day.

A second option is to empirically determine the efficiency of your particular panels. Just because the label states 355Watts, that doesn't mean your panels in the real-world will actually produce 355W. You determine this with a volt/clamp meter that can measure DC current. You point the test panel exactly at the sun at noon, and measure the volts/amps you can get out of it while under load. Let's say you measure 8.42A at 39.2V. That works out to be 330W, which is 338W/355W =93% efficient. You use that 0.93 as a fudgefactor to determine what you can actually produce in the real-world.

So, assuming you have (2130W/25V charging) X 0.93 = 79.2 real-world Amps. It would work.

Here's are fudgefactor values I have measured before for panels that I own. I usually use about 0.87X as an overall generic fudgefactor for any panel.
Renogy 300W, 0.85ff
YingLi 245W, 0.87ff
Astronergy 240W, 0.94ff

 

[Bud Martin]

I should clarify my statement that the extra amps will be discarded. That was a poor description. I should have said that 6 of those panels have the potential to produce enough amps that a big enough SCC could generate up to 96A to the battery. With your SCC you are giving up some of that potential.

I think in the real use with his 6 panels, he will be getting close to 80A due to conversion and system loss.
I think OP should wire up and with proper protection, I.E. fuses, and track the result.
The reason I over panel my system is so I can get enough power during winter time or when I have cloudy days.

 

[Jgoodman]

Okay so out of curiosity, not saying I’m gonna do this just collecting info. What would happen if I just plugged six panels into a 6-1 y connection. Then went to the controller

 

[Jgoodman]

And just so I fully understand, you are saying hook the positive of on panel to the negative of another, then hook the positive and negative that are still unhooked into the y connection that goes to the scc, then repeat with the remaining panels. So I have three positive and three negative wires from the panels to the y connection then the scc, fusing where applicable correct, Bud Martin?

 

[Jgoodman]

And would it be 30amp fused or sixty amp fused

 

[time2roll]

Okay so out of curiosity, not saying I’m gonna do this just collecting info. What would happen if I just plugged six panels into a 6-1 y connection. Then went to the controller

Each panel is 9 amps. That would be 54 amps through the 6-1 adapter rated for 30 amps.

 

[MichaelK]

Okay so out of curiosity, not saying I’m gonna do this just collecting info. What would happen if I just plugged six panels into a 6-1 y connection. Then went to the controller

Ummm, fire?

 

[Jgoodman]

Ummm, fire?

Lol I appreciate the honesty

 

[Bud Martin]

And just so I fully understand, you are saying hook the positive of on panel to the negative of another, then hook the positive and negative that are still unhooked into the y connection that goes to the scc, then repeat with the remaining panels. So I have three positive and three negative wires from the panels to the y connection then the scc, fusing where applicable correct, Bud Martin?

I do not quite understand what you are saying.
What you will do is to create 3 strings of panels, each string will have two panels in series and with a fuse in series (I use MC4 fuse holder) of the string, then you will put the 3 strings in parallel using 3 to 1 Y adapter or combiner box that can handle at least 30A to feed the LV2424 using 8AWG PV wires.
The 30A fuse rating is the max rating you can use, you can use 15 ~20A fuse for each string also which will in sure that it will blow if you have shorted panel.

 

[Jgoodman]

I do not quite understand what you are saying.
What you will do is to create 3 strings of panels, each string will have two panels in series and with a fuse in series (I use MC4 fuse holder) of the string, then you will put the 3 strings in parallel using 3 to 1 Y adapter or combiner box that can handle at least 30A to feed the LV2424 using 8AWG PV wires.
The 30A fuse rating is the max rating you can use, you can use 15 ~20A fuse for each string also which will in sure that it will blow if you have shorted panel.

That’s the info I was looking for, appreciate the advice

 

[Bud Martin]

That’s the info I was looking for, appreciate the advice

Make sure to check the Voltage and polarity of each string, then check again when you add another string in parallel, then recheck them again when you parallel the third string before connecting the whole thing to the SCC.