Solar panel fuse

Shamu341

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Hi, I'm in the process of installing a new solar pane as the previous one give up the ghost.
The charge controller I'm using is a Solar SR135TL, the in-line fuse is missing but I think it was 7.5amp although not sure.

Would a 7.5 fuse be ok for this controller the rating of which is 8 amp?. The panel is a Wattstunde 65w
 

rogerthebodger

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Are you talking about a fuse between the panel and controller or between the controller and the battery/

The fues between the controller and the battery is requird close to the battery less so between the panel and the controller
 

KompetentKrew

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I can't see how you could blow a 7.5A fuse on the 12V side of the controller with a 65W panel.

I'd expect to get about 4.5A - 5.5A at 12V - 14V to get your 65W.

But I know nothing about solar, so no doubt someone will be along shortly to tell me that I'm wrong because I haven't accounted for…
 

Pete7

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The SR135TL is quite a good PWM solar controller, but I don't remember a fuse so if its a separate in line wasn't part of the original controller. Could be the wiring from the controller to the battery is too small. I would put a 10A fuse in line with new wiring and carry on.
 

PaulRainbow

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Hi, I'm in the process of installing a new solar pane as the previous one give up the ghost.
The charge controller I'm using is a Solar SR135TL, the in-line fuse is missing but I think it was 7.5amp although not sure.

Would a 7.5 fuse be ok for this controller the rating of which is 8 amp?. The panel is a Wattstunde 65w
The controller rating is the max permissible current, the 65w panel will be less. A 5a fuse will be adequate.
 

Shamu341

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The wiring to the battery is fairly chunky.
The controller rating is the max permissible current, the 65w panel will be less. A 5a fuse will be adequate.
So nor harm then if I use a 7.5a?
 

VicS

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I can't see how you could blow a 7.5A fuse on the 12V side of the controller with a 65W panel.

I'd expect to get about 4.5A - 5.5A at 12V - 14V to get your 65W.

But I know nothing about solar, so no doubt someone will be along shortly to tell me that I'm wrong because I haven't accounted for…
Any connection to the battery should be fused to protect the wiring from the high current the battery could deliver in the event of a short circuit, The installation instructions recommend 20 amps ( to protect 4mm2 wiring)

The SR135TL is quite a good PWM solar controller, but I don't remember a fuse so if its a separate in line wasn't part of the original controller. Could be the wiring from the controller to the battery is too small. I would put a 10A fuse in line with new wiring and carry on.
I would go along with your suggestion of a 10 amp fuse for the installation in question

The wiring to the battery is fairly chunky.
The controller rating is the max permissible current, the 65w panel will be less. A 5a fuse will be adequate.
So nor harm then if I use a 7.5a?
I'd expect 7.5 amps to be OK
 

thinwater

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In the UK you will probably never see more than 50-65% of the rated wattage, due to low sun angle and partially charged batteries. 65 W is theoretically impossible away from the tropics; even if you adjust to a 90 degree sun angle, there is still increase atmospheric absorption. This is why you UV index is typically a paltry 7-8 vs. 9-11 in Florida. So more like 3 amps max. on the best day, and 2-2.5 most of the time.
 
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