Adding one more panel

[MrWegas]

W have on the roof 3 RICH SOLAR 170 Watt 12 Volt Moncrystalline Solar Panels connected in SERIES. I want to add one more panel to have total 680W. Probably I'll never hit that maximum Watts. 80% is 544W.

Question is how to connect 4 panels, to charge my 2 Battle Born batteries (12V system.)
a. All in Series
b. 2+2 in series and parallel

I'm asking because I have EPEVER MPPT Solar Charge Controller 40A 150V PV . Specs are:
40A MPPT Charge Controller Nominal System Voltage: 12V, 24V
Rated Charge Current: 40A
Max PV Open Circuit Voltage: 150V / 138V
Max PV Input Power: 520W (12v battery)

Panel specs:

• Maximum Power(Pmax): 170W
• Maximum Power Voltage(Vmp): 18.4V
• Maximum Power Current(Imp): 9.24A
• Open Circuit Voltage(Voc): 22.6V
• Short Circuit Current(Isc): 9.79A

 

[Supervstech]

The decision between all in series or some parallel etc is.., shading. All panels in series will drop output if any panel gets shading. But series keeps the amps low, so smaller conductors can feed the controller.

parallel isolates shaded panels from affecting total output, but raises tha amp load, requiring larger conductors...

 

[MisterSandals]

Yes to what Supervstech said but given the choice, (and minimal or no shading), all 4 in series will make your MPPT much happier. Even at 88Voc, you are on the low side of the voltage it excels at (approaching 100% of max input).
In terms of max input watts, this usually is the amount where watts above this are clipped/discarded. Some implement a panel strategy where they expect some clipping but benefit more during low light conditions (morning/evening/cloudy).

 

[MrWegas]

Im asking is it ok to have 4x170W=680 when charge controler has Max PV Input Power: 520W .

 

[MisterSandals]

Im asking is it ok to have 4x170W=680 when charge controler has Max PV Input Power: 520W .

Because your SCC has that wording, I'll walk back my earlier statements. I think the only answer anybody "should" give you is to ask the manufacturer.

I think this particular question is fairly uncommon because most SCC's (all that i have seen which is less than 10) specify max input volts and max input amps.
And this has been pretty standard advice, "just stay under max volts with Voc and current with Isc".

Sorry, I wish i had a better answer. Maybe someone else heard from the manufacturer and knows the reason for this odd wording (and it could be part of a language translation process). There are a LOT of these in use so maybe you'll get some advice from real world experience.

Good luck, chime back in if you get an answer, especially with the details of this limit.

 

[Bob142]

Im asking is it ok to have 4x170W=680 when charge controler has Max PV Input Power: 520W .

@MrWegas check the manual for your specific Epever SCC. Both the Tracer AN and BN lines assert that you can have a max PV array power much higher than the rated charge power. For example:

Tracer BN:


Tracer AN:

 

[offgriddle]

I also have the Epever Tracer BN 40 amp SCC and have been studying the specifications and reading the very valuable information provided by forum members.

Correct me if i am wrong, but according to the BN's specs., one could wire in series as many panels as they want AS LONG as the open circuit, (aka the unloaded), added voltages of the panel string does not exceed 150 volts, (138 volts at or above 70 degrees Fahrenheit).

I have heard some grumblings from others regarding the Epever's 150 volt maximum specifications not being realistic, so, when I add more panels as my system grows, I am going to keep the open voltage output of my panels to somewhere between 100 and 125 volts AND I am going to employ a series/parallel arrangement to not only control my open circuit voltage output but also assure some production on shady cloudy days.

Photo : "The Beast"

 

[MrWegas]

I thought that OCV is the most importan for calculation, so Open Circuit Voltage(Voc): 22.6V x 4 = 90.4V, ant thats below 150V/138V. I'm still confused how they come up with 520W@12V. The way I see it you can put 6x22.6=138, in this case it would be 6 panels 6x170W=1020W

 

[MrWegas]

Who can explain what is RATED CHARGE POWER and MAX PV ARRAY POWER and how do I use those numbers

 

[MrWegas]

Based on this video:
18.4Vx9.24A=170.016W and thats one panel.

Panel specs:

• Maximum Power(Pmax): 170W
• Maximum Power Voltage(Vmp): 18.4V
• Maximum Power Current(Imp): 9.24A
• Open Circuit Voltage(Voc): 22.6V
• Short Circuit Current(Isc): 9.79A

 

[MisterSandals]

confused how they come up with 520W@12V.

Agreed. The math with the volt and amp limits does not match.

Unless you are willing to roll the dice, or get definitive answers from someone in the know, you really gotta contact the manufacturer.

 

[MrWegas]

Agreed. The math with the volt and amp limits does not match.

Unless you are willing to roll the dice, or get definitive answers from someone in the know, you really gotta contact the manufacturer.

It's Chinese product. That's not easy to contact.

 

[MisterSandals]

It's Chinese product. That's not easy to contact.

Maybe that's a clue as to what SCC you should buy... just sayin'.

 

[Supervstech]

I thought that OCV is the most importan for calculation, so Open Circuit Voltage(Voc): 22.6V x 4 = 90.4V, ant thats below 150V/138V. I'm still confused how they come up with 520W@12V. The way I see it you can put 6x22.6=138, in this case it would be 6 panels 6x170W=1020W
View attachment 10822

Agreed. The math with the volt and amp limits does not match.

Unless you are willing to roll the dice, or get definitive answers from someone in the know, you really gotta contact the manufacturer.

I don’t understand what everyone is confused on...

520W is 43A... so... a 40A charge controller cannot put out more amps at 12V(14.4)

 

[MisterSandals]

I don’t understand what everyone is confused on...

520W is 43A... so... a 40A charge controller cannot put out more amps at 12V(14.4)

Nobody is suggesting it will put out more than 40A.

The question is what happens if his panels produce 4x170W=680W (@ 9.79A)?

 

[Supervstech]

Yeah, that is a manufacturer question. Some controllers will handle the high input, and just keep outputting rated current, clipping the input... some will just fail.

 

[Bob142]

Nobody is suggesting it will put out more than 40A.

The question is what happens if his panels produce 4x170W=680W (@ 9.79A)?

Please see my post above. The OP needs to read the manual. It describes the difference between rated charge power and max PV power, how the unit manages the overage, and what all the applicable limits are.

 

[ghostwriter66]

You need to go back and read @Bob142 post .. he is 100% right ... The TRACER 4315BN is my go-top SCC .....Too many ppl are confusing input and output .. these things are forgiving when pushing too many amps in -- BUT will NOT FORGIVE tooooo much voltage at all ...

ALSO -- the higher VOLTAGE you put in -- the sooner in the monring and later in the day your solar panel will kick in and start making power ...

But the EPSOLAR manual is well written and they have a GREAT Help desk that speaks GOOD ENGLISH ...

 

[ghostwriter66]

I also have the Epever Tracer BN 40 amp SCC and have been studying the specifications and reading the very valuable information provided by forum members.

Correct me if i am wrong, but according to the BN's specs., one could wire in series as many panels as they want AS LONG as the open circuit, (aka the unloaded), added voltages of the panel string does not exceed 150 volts, (138 volts at or above 70 degrees Fahrenheit).

I have heard some grumblings from others regarding the Epever's 150 volt maximum specifications not being realistic, so, when I add more panels as my system grows, I am going to keep the open voltage output of my panels to somewhere between 100 and 125 volts AND I am going to employ a series/parallel arrangement to not only control my open circuit voltage output but also assure some production on shady cloudy days.

Photo : "The Beast"

View attachment 10813

I push the BN right up to 130V with NO issues ... the only concern is that at 149 it will work all day -- and at 151 it lets out the "Factory Smoke" .. i kid you not ... NOW I will never exceed the voltage --BUT the suggested watt/amp is something i play wiht all the time -- usually pushing the 130% level ... Still pisses me off though that they do not make their lugs big enough to fit REAL cables ...

 

[MisterSandals]

BUT the suggested watt/amp is something i play wiht all the time -- usually pushing the 130% level

Max PV Input Power: 520W (12v battery)

Okay, good to have some real world experience with this. Granted it is probably a LOT easier to push the company's SCC to 130% than pushing your own personal SCC.
So you recommend 520W x 1.3 = 676W as "safe"? Asking for a friend.