While troubleshooting a commercial system i found 2 out of 14 PV string fuses blown.
The fuses are 12 A/600VDC.
1. Funny thing is 156% times PV Isc is covered by above 12 Amp fuse rating. ( PV Isc = 7.38 A. Multiply by 156% = 11.51 A. < 12 A fuse)
Shouldn't the 12A fuse be just adequate?
2. Funny thing #2, I seem to recall Wiles mentioning that fuses only need the 125% times Isc rating........
That could - in THEORY - mean even LOWER Amp fuses, no??
3. Funny thing #3, this is happening on both systems 7 years after install.
a. Do fuses get tired?:?
b. Did we just have some freak solar storm?
c. Should i be happy and think these panels reached their peak burst of power (momentarily) 7 years in???
OK, I realize original designer was a bit over-zealous in choosing the minimum 12 A size that was calculated as possible. The panel could use 15A fuses based on their series fuse rating.
Here, the problem is solved ( I BELIEVE).
I am getting all 15 Amp fuses for all strings.
I hate the thought of one fuse causing 2KW to shut down for who knows how long.....
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
However, it makes me think: i don't want these problems on my systems in the coming years! :rant::rant::rant:
I kinda like the type of work....that pays.:thumbsup:
For example, i am installing SUNIVA 260's. Isc = 9.01 A. at 156% = 14.06 A.
The wholesaler says series fuse rating is 15A. YET, 15 A fuse relative to the 156% of Isc is really just as much as the problems above.
I'm gonna do 20A fuses.
(Especially as my DC CB is on roof, as always, in the HEAT.)
Your thoughts, as always, appreciated!
The fuses are 12 A/600VDC.
1. Funny thing is 156% times PV Isc is covered by above 12 Amp fuse rating. ( PV Isc = 7.38 A. Multiply by 156% = 11.51 A. < 12 A fuse)
Shouldn't the 12A fuse be just adequate?
2. Funny thing #2, I seem to recall Wiles mentioning that fuses only need the 125% times Isc rating........
That could - in THEORY - mean even LOWER Amp fuses, no??
3. Funny thing #3, this is happening on both systems 7 years after install.
a. Do fuses get tired?:?
b. Did we just have some freak solar storm?
c. Should i be happy and think these panels reached their peak burst of power (momentarily) 7 years in???
OK, I realize original designer was a bit over-zealous in choosing the minimum 12 A size that was calculated as possible. The panel could use 15A fuses based on their series fuse rating.
Here, the problem is solved ( I BELIEVE).
I am getting all 15 Amp fuses for all strings.
I hate the thought of one fuse causing 2KW to shut down for who knows how long.....
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
However, it makes me think: i don't want these problems on my systems in the coming years! :rant::rant::rant:
I kinda like the type of work....that pays.:thumbsup:
For example, i am installing SUNIVA 260's. Isc = 9.01 A. at 156% = 14.06 A.
The wholesaler says series fuse rating is 15A. YET, 15 A fuse relative to the 156% of Isc is really just as much as the problems above.
I'm gonna do 20A fuses.
(Especially as my DC CB is on roof, as always, in the HEAT.)
Your thoughts, as always, appreciated!