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Hello,
I've have 6 x 110w 20V flexible solar panels connected in series on my narrowboat which are all connected to a Mastervolt SCM60 MPPT-MB. They came from a reputable UK supplier. They're about 5 years old now.
Over the last year and a half, I've had 3 out of the 6 fail at the junction box where it has heated up and deformed the lid and plastic casing. It's always the last panel in line - I bypass it, and then - a few months later, the same thing happens again to the new 'last' panel. As these are all stuck down to the roof of the boat I really want to understand why this might be happening and then - secondarily - if there was anything I can do to repair them or buy replacement junction boxes.
As mentioned, I've disconnected each of the panels each time it's gone into fault. I've also investigated inside one of the junction boxes and the burn marks are not near the diodes (marked SB1-045L but where the circuit is connected to the main outgoing cables. I've had failures at both the +ve and -ve end.
The MPPT is rated at 145V. I believe the max system voltage of the panels was quoted at 600V when I purchased them, so Vmax = 120. As I've had 3 fail, Vmax would have reduced each time, so the last failure was at Vmax = 80.
Many thanks,
Duncan
Junctionboxsmall.jpgSolarpanelssmall.jpg
I've have 6 x 110w 20V flexible solar panels connected in series on my narrowboat which are all connected to a Mastervolt SCM60 MPPT-MB. They came from a reputable UK supplier. They're about 5 years old now.
Over the last year and a half, I've had 3 out of the 6 fail at the junction box where it has heated up and deformed the lid and plastic casing. It's always the last panel in line - I bypass it, and then - a few months later, the same thing happens again to the new 'last' panel. As these are all stuck down to the roof of the boat I really want to understand why this might be happening and then - secondarily - if there was anything I can do to repair them or buy replacement junction boxes.
As mentioned, I've disconnected each of the panels each time it's gone into fault. I've also investigated inside one of the junction boxes and the burn marks are not near the diodes (marked SB1-045L but where the circuit is connected to the main outgoing cables. I've had failures at both the +ve and -ve end.
The MPPT is rated at 145V. I believe the max system voltage of the panels was quoted at 600V when I purchased them, so Vmax = 120. As I've had 3 fail, Vmax would have reduced each time, so the last failure was at Vmax = 80.
Many thanks,
Duncan
Junctionboxsmall.jpgSolarpanelssmall.jpg
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