Fast and Fast Fast Acting Fuses

[Arrowshot]

To all,
Building a new array using 10 100 watt panels with a 6 string combiner box putting five pairs of panels into five strings. Was looking at using fast (link) and (link) acting fuses for the combiner box in the event of a solar event. Would these fuses trip off quicker preventing damage to the panels?

 

[hwy17]

What kind of solar event?

 

[yodamota]

lots of people use circuit breakers for under 150vdc. Some combiner boxes come with circuit breakers for this exact purpose. Why not use a circuit breaker?

I also wonder why you want 5 strings of 2 panels? Are you using PWM chargers?

 

[robbob2112]

I would be looking at the 'time current curves' for "Fast acting" fuses. Goodle and look that up for any fuse you pick.

For larger currents many people use the MRBF and Class T fuses, but they both respond in 0.01 to 0.1 seconds but only to a current 6x the rated capacity. For currents of only 2x the rated amps they will hang in there several minutes. These both have high interupt DC current ratings.

Ceramic fuses give you higher interupt current rating than just glass with a filament typically but at the low current you will get out of panels that isn't typically a problem. And typically a glass with fillament type will have a faster curve than the ceramic fuse of the same size. We are talking micro/pico second differences.

 

[time2roll]

I venture to guess a solar event that opened those fuses could still damage the panels.
However if the fuses do open due to a fault it will prevent the power from the other four strings from escalating the damage or issues with the faulted string.

 

[MattiFin]

To all,
Building a new array using 10 100 watt panels with a 6 string combiner box putting five pairs of panels into five strings. Was looking at using fast (link) and (link) acting fuses for the combiner box in the event of a solar event. Would these fuses trip off quicker preventing damage to the panels?

Event?
In solar flare or CME: no
Sun turning to red giant in the future: no

 

[time2roll]

Honestly with pairs of 100w panels the voltage is low enough I would skip fuses even if technically required.

 

[robbob2112]

I would just string all 10 panles together if the MPPT or PWM allows it, or get another. Simpler and easier. Why run all the wires for 5 separate strings? That way you need 1 breaker/SPD back where the wire terminates.


AND whatever you do, don't forget the extra ground conductor (EGC) to the mount location to attach to the panel frames to. Keep them all at the same potential as the MPPT/PWM/etc.


Maybe the OP should post a generic plan of what he is doing at this point.

 

[Arrowshot]

Thanks for the answers!!!