Solar Confusion

Nodak7

Nodak7

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Sep 28, 2008
1,256
Hunter 41DS Punta Gorda, FL
OK I need to help! I have a pair of LG395 Fixed Panels connected to a single Victron MPPT Smart 150/60 Controller. From there I have a 60A Breaker to my battery bank of 6 Trojan T105's 6v 3 sets of 2 in parallel. The system worked fine for awhile then started tripping the 60A Breaker when the sun was brightest. I changed the breaker but is continued to do that. I thought maybe the two panels might be to much for the battery bank so I installed a switch to isolate one panel. That worked fine for awhile but then the breaker started tripping again. Now even when the breaker is set it is not charging the battery bank. Question! Is it the panels or Mppt or breaker that is bad. I checked the batteries and they seem good. The MPPT shows a solar panel voltage but no amperage (see picture). I thought it might be a bad breaker so I have one on order. I am leaning towards a bad Controller but wonder about the panels since they got shaken up pretty badly during Ian but the system did work for awhile after but now nothing. I checked the panels for damage they look good but i have no clue how to check the panels for voltage other than thru the controller. Any suggestions?
 

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Hollyberry

Hollyberry

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Sep 24, 2021
386
Beneteau 35s5 Telegraph hrbr Thetis Island
40V at panel looks like an open circuit situation...
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,086
Catalina 34 224 Maple Bay, BC, Canada
Have you measured voltage(s) at all the points along the way during operation?
Are your batteries full?
Have you read the troubleshooting guide for your controller? Many controllers require disconnecting the panels before the batteries, so why a breaker, not a fuse? Could be that breaker has snafued your controller.
What is the 60A breaker protecting? It should be sized for the wire not the load. What size is the wire between the battery bank and the controller where the fuse is located? If, indeed, you installed it to protect the wiring from a battery short it should be a fuse, not a breaker.
Have you checked each and every one of the multiple connections, not only visually but physically?
 
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heritage

heritage

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Apr 22, 2011
949
Hunter 27 Pecan Grove, Oriental, NC
Your LG 395s can put out nearly 400 watts. That is about 30 amps at 13 volts. Both panels connected in parallel would be 60 amps. Wouldn't hurt to try an 80 amp breaker if your cable to the batteries can handle it.
 
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mermike

mermike

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Nov 21, 2012
765
Yamaha 33 Port Ludlow, WA
Have you measured the current from the controller to the battery with a clamp meter?
 
J

JBP-PA

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Apr 29, 2022
641
Jeanneau Tonic 23 Erie, PA
A victron 150/60 should have been precinfigured to limit the output current at 60 A. You could try setting the controller to limit at a smaller current.
 
Johann

Johann

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Jun 3, 2004
522
Leopard 39 Pensacola
The Victron manual for the 150/60 calls for a minimum circuit breaker rating of 70A and a maximum of 80A. This is likely the cause of your breaker tripping. As far as the MPPT not charging the batteries, what are the indications of that? The screenshot shows the MPPT in float with a battery voltage of 13.93v. This is above the specified float voltage for the Trojans of 13.5v, so you wouldn’t expect any current to be flowing into the battery.
 
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Hello Below

Hello Below

.
May 7, 2012
1,567
Hunter e33 Maple Bay, BC
Johann said:
The Victron manual for the 150/60 calls for a minimum circuit breaker rating of 70A and a maximum of 80A.
Click to expand
So in other words RTFM. Good researching. That should be worth a couple of libations of your choice.

Johann said:
The screenshot shows the MPPT in float with a battery voltage of 13.93v.
Click to expand
Probably on its way down from the Bulk/Absorption stage.
 
Nodak7

Nodak7

.
Sep 28, 2008
1,256
Hunter 41DS Punta Gorda, FL
Nodak7 said:
OK I need to help! I have a pair of LG395 Fixed Panels connected to a single Victron MPPT Smart 150/60 Controller. From there I have a 60A Breaker to my battery bank of 6 Trojan T105's 6v 3 sets of 2 in parallel. The system worked fine for awhile then started tripping the 60A Breaker when the sun was brightest. I changed the breaker but is continued to do that. I thought maybe the two panels might be to much for the battery bank so I installed a switch to isolate one panel. That worked fine for awhile but then the breaker started tripping again. Now even when the breaker is set it is not charging the battery bank. Question! Is it the panels or Mppt or breaker that is bad. I checked the batteries and they seem good. The MPPT shows a solar panel voltage but no amperage (see picture). I thought it might be a bad breaker so I have one on order. I am leaning towards a bad Controller but wonder about the panels since they got shaken up pretty badly during Ian but the system did work for awhile after but now nothing. I checked the panels for damage they look good but i have no clue how to check the panels for voltage other than thru the controller. Any suggestions?
Click to expand
Thanks all for your help on this! Indeed the problem was a bad breaker. The panels were a total of 790w and when the sun got high and bright they were generating 65.8 amps thus tripping the breaker which eventually gave up the ghost and failed after a number of resets. I have changed it to an 80A breaker and everything seems to be working properly. Thanks again!
 
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jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,392
CAL 35 Cruiser #21 moored EVERETT WA
Nodak7 said:
I have changed it to an 80A breaker
Click to expand
Sounds like a good resolution. I trust you checked the wires to and from the breaker... They can safely handle 80 amps?
 
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mermike

mermike

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Nov 21, 2012
765
Yamaha 33 Port Ludlow, WA
jssailem said:
They can safely handle 80 amps?
Click to expand
Try the Circuit Wizard at http://circuitwizard.bluesea.com/. (Note: it is offline at the moment) Enter the system voltage (12VDC), Current (80A), Voltage drop (3%), and round-trip length of wire to and from the battery. The recommended cable size should be smaller than or match the cable you're using. If it is not, you need to match the breaker to the cable or increase the cable size.
 
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Nodak7

Nodak7

.
Sep 28, 2008
1,256
Hunter 41DS Punta Gorda, FL
jssailem said:
Sounds like a good resolution. I trust you checked the wires to and from the breaker... They can safely handle 80 amps?
Click to expand
Yup #6 wire (3' run) should be more than sufficient.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,392
CAL 35 Cruiser #21 moored EVERETT WA
That is an easy tool to use. Both amp capacity and wire size tools.

EC50355F-67B8-4B74-AA59-945E544576A9.png

The design conditions influence the recommended wire sizes to meet ABYC Standards.
 
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Johann

Johann

.
Jun 3, 2004
522
Leopard 39 Pensacola
jssailem said:
That is an easy tool to use. Both amp capacity and wire size tools.

The design conditions influence the recommended wire sizes to meet ABYC Standards.
Click to expand
Yep, just gotta be sure to select the proper insulation rating. I wish it defaulted to 105C which is what most are using I believe.
 
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Nodak7

Nodak7

.
Sep 28, 2008
1,256
Hunter 41DS Punta Gorda, FL
Thanks again all! I did go back and rechecked my wire size using the ABYC Wire Size Calculator and it confirmed that 6 Ga wire was sufficient for a 6' run at 80amps, 12v. In actuality the amps would be max approximately 70 since there is a max 10% variation in the output for the Victron (60amp +6amp). I think I am good to go!
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
23,086
Catalina 34 224 Maple Bay, BC, Canada
Johann said:
Yep, just gotta be sure to select the proper insulation rating. I wish it defaulted to 105C which is what most are using I believe.
Click to expand
As an engineer (HVAC, electrical plumbing and fire protection for buildings) I am both amazed and discouraged by these "handy dandy" online calculators.
They have advantages in user simplicity and rapid answers.
Compared to written/printed/online TABLES,, I think they have possibly severe shortcomings:
1. The old adage GIGO holds true. Many folks who use them may include input errors, as well as NOT being aware of DEFAULT values in the "programs" themselves as Johann quite correctly notes. The casual user never knows if they've made an error.
2. Compared to charts and tables, the user of these "programs" never allows you to clearly see the RELATIONSHIPS between length, voltage drop and wire size (to say nothing of insulation types and ambient temperature) [without doing multiple inputs, that is]. The superb BlueSeas tables for wire sizing and fuse sizes clearly show how just a small change in any of the variables can impact the choices you make in wire and fuse sizes. You can easily see, right in front of you, for example how a just a four or five foot difference in length may or may NOT change the wire size. I believe it gives you a greater sense of security in your planning. For example, when sizing alternator output wire, you can easily see how the differences in amperage output affect wire sizes for any given length and how important or maybe not the length of cables can and do.

Here is the BlueSeas table link:

The Correct Size Wire And Fuse - Wire Size Chart table:
https://d2pyqm2yd3fw2i.cloudfront.net/files/resources/reference/20010.pdf

One way to deal with possible cognitive disconnect is to simply check BOTH. I think Nodak may be surprised that I see the BlueSeas table says 6 feet 80A as 4awg, but maybe it's my failing eyesight. ;) There's nothing in the 3% table that uses 6awg under the 80A column, only the 70A column.
 
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Johann

Johann

.
Jun 3, 2004
522
Leopard 39 Pensacola
Stu Jackson said:
I think Nodak may be surprised that I see the BlueSeas table says 6 feet 80A as 4awg, but maybe it's my failing eyesight. ;) There's nothing in the 3% table that uses 6awg under the 80A column, only the 70A column.
Click to expand
Indeed. I am surprised also. But I notice the circuit length is 0-20‘. If you input 20’ into the BoatHowTo calculator you get 3AWG with the note that it is based on the 3% voltage drop requirement, which exceeds the ampacity requirement. If you input 6’ you get 8AWG with a note that it is based on ampacity.

I always like to use this chart for ampacity and calculate voltage drop separately so I know how close I am to each limit.

 
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