Forum Discussion

EMD360's avatar
EMD360
Explorer
May 11, 2022

Tripping solar panel breaker

Last fall I installed two Solarland 180w PERC panels. I had ordered three 100 watt but changed my mind and bought the two 180’s. Unfortunately I didn’t resize my order for the panel breaker which is 15 amps. The 100 watt panels were rated for five amps each but these are at 9.42 each. So now that we are getting really sunny days my panel breaker is tripping. I thought ok I’ll have to replace it with a 20. But I was watching the power when I was trouble shooting and thought I might have briefly seen more than 20 amps. Would a 30 amp fuse of these two panels be too high? The MPPT controlller is Victron. The system side breaker is 40 amps.
  • StirCrazy's avatar
    StirCrazy
    Moderator
    May 12, 2022
    EMD360 wrote:
    Last fall I installed two Solarland 180w PERC panels. I had ordered three 100 watt but changed my mind and bought the two 180’s. Unfortunately I didn’t resize my order for the panel breaker which is 15 amps. The 100 watt panels were rated for five amps each but these are at 9.42 each. So now that we are getting really sunny days my panel breaker is tripping. I thought ok I’ll have to replace it with a 20. But I was watching the power when I was trouble shooting and thought I might have briefly seen more than 20 amps. Would a 30 amp fuse of these two panels be too high? The MPPT controlller is Victron. The system side breaker is 40 amps.


    can you change the wiring to a series setup instead? this will keep your incoming amprage low but raise the voltage, so you'll be able to get a bit better efficency out of that MPPT controler. I have a old PWM controler on my three 180 watt panels on my 5th wheel and I see 22amps quite often, I am looking at changing the controler to a MPPT so I can put them in series. in parralel with a 8 ga wire you are looking at losing up to 0.38V over 10 feet, in series that would be a voltage drop of 0.19. doesnt sound like much but it adds up..

    Steve
  • EMD360's avatar
    EMD360
    Explorer
    May 12, 2022
    As I understand it series wiring means the panels have to both be working at the same efficiency to get maximum power from them. So partial shading impacts the total power available more. Most campsites have at least partial shade. So I opted for parallel wiring. Am I wrong about that? I believe I read that was the case.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    May 12, 2022
    StirCrazy wrote:
    I am looking at changing the controler to a MPPT so I can put them in series. in parralel with a 8 ga wire you are looking at losing up to 0.38V over 10 feet, in series that would be a voltage drop of 0.19. doesnt sound like much but it adds up..
    Series also has greater shade tolerance/power with panels that have bypass diodes (most have them).

    My 3 series 30V panels have 3 bypass diodes, so 10V per panel section. I've seen charging at 20V increasing in 10V increments to 90V due to a leafy shade tree. ie The 20V can be from 2 different panels. Parallel would require sun on the entire panel and hence charging would occur with 1, 2 or 3 panels with sun.
  • 2oldman's avatar
    2oldman
    Explorer II
    May 12, 2022
    EMD360 wrote:
    So partial shading impacts the total power available more... So I opted for parallel wiring. Am I wrong about that?.
    Depends on the panel. Bypass diodes allow for shading by shutting down that part of the panel. If no diodes are in the panel, then yes, a series setup will shut it all down.

    I have 6 panels in series and I don't really notice that much of a degradation of power with partial shade. YMMV
  • EMD360's avatar
    EMD360
    Explorer
    May 12, 2022
    2oldman wrote:
    I don't know why you have to fuse panels.


    Apparently you don’t if wired in series. The amps are not high enough to damage the wires if there is a short circuit.
    That’s what the windynation site that was shared explained.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    May 13, 2022
    2oldman wrote:
    I don't know why you have to fuse panels.
    Serial and 2 parallel panels don't need a fuse. 3 or more panels can cause a fire in a shorted panel and hence each panel should be fused at the combiner box to prevent excessive amps to the defective panel.
  • LittleBill's avatar
    LittleBill
    Explorer
    May 13, 2022
    how do u find out how many bypass diodes are in a panel? I don't think I have ever seen that listed?
  • EMD360's avatar
    EMD360
    Explorer
    May 13, 2022
    I could not find any reference to bypass diodes in the specs for my panels but in a general explanation of bypass diodes I read that most panels have three. They are located in the junction box on the panel. Here is the diagram of the Solarland box. I’m assuming the three sections are bypass diodes.

  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    May 13, 2022
    LittleBill wrote:
    how do u find out how many bypass diodes are in a panel? I don't think I have ever seen that listed?
    It should be in the specs or panel information. Opening the junction box will reveal the diodes.

    It's common for 1 diode per 2 rows. So a 60 cell panel is 10x6 cells with a diode for every 10x2 section, so 3 diodes.
  • StirCrazy's avatar
    StirCrazy
    Moderator
    May 13, 2022
    CA Traveler wrote:
    StirCrazy wrote:
    I am looking at changing the controler to a MPPT so I can put them in series. in parralel with a 8 ga wire you are looking at losing up to 0.38V over 10 feet, in series that would be a voltage drop of 0.19. doesnt sound like much but it adds up..
    Series also has greater shade tolerance/power with panels that have bypass diodes (most have them).

    My 3 series 30V panels have 3 bypass diodes, so 10V per panel section. I've seen charging at 20V increasing in 10V increments to 90V due to a leafy shade tree. ie The 20V can be from 2 different panels. Parallel would require sun on the entire panel and hence charging would occur with 1, 2 or 3 panels with sun.


    yup, I know that also, was just looking at the efficiency of voltage drop in this senario. also lowering the amps on his line.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,187 PostsLatest Activity: Jan 14, 2025