blowing fuse on external panels

Trailpixie

i am using a victron MPPT 75|15 and. keep blowing it's 30 amp fuse. I'm not sure what to look at. I have a 30 foot 10 gauge cable, but the fuse is blowing before I even connect to the solar panels. As soon as I plug it into the connector, the fuse blows.

AnOldUR

Polarity? SAE ports can be tricky.

MuttonChops

Trailpixie said:
. . . have a 30 foot 10 gauge cable,

. . .  the fuse is blowing before I even connect to the solar panels.
       As soon as I plug it into the connector, the fuse blows.

You are saying you have the SAE Port <> a 30-foot extension cable <> a solar panel.
And the Controller fuse is blowing when the 30-foot extension cable ONLY is plugged in, Yes?

That sounds like a 30-foot extension cable short.  Even if your SAE Port and solar panel polarity are wrong the Controller fuse would not fail when a fully open extension cable was attached.

Marceline

Trailpixie said:

i am using a victron MPPT 75|15 and. keep blowing it's 30 amp fuse. I'm not sure what to look at. I have a 30 foot 10 gauge cable, but the fuse is blowing before I even connect to the solar panels. As soon as I plug it into the connector, the fuse blows.

I'm not sure if it will make a difference but when I plug my portable panel into my Victron controller I keep the panel face down or folded when I plug it in, then turn it to the sun afterwards.

Trailpixie

It was reversed polarity. 

  [embarassed] 

Now I have spent two days trying to get their performance up to par. At first I was getting 50 or 60 watts, so I made sure to set the controller with all the key settings from the Battleborn site that match those on the camper's onboard controller. After doing that, my performance went down to 30 watts. I returned the panels to default and they spiked back up to 135 watts. I used the LifePO preset which are nearly the same as Battleborn and the performance went back down to 100 watts. 

Inconceivable!

200 watt panels. Clear blue sky. full southern sun exposure. Battery at 73%. That's further off theoretical 200 watt spec than I would have expected. settings in the controller seem impenetrably complex, fussy, and difficult to find. Battleborn site is simplistic and vague. every time I try to manually configure settings, performance drops to 30 watts and stays there. (full sunny day at 2:00 in the afternoon.)

Any suggestions?

Bayliss

@Trailpixie, what brand/design panels are you using?  Have you tried adjusting the angle of the panels in relation to the sun.  Often, when I do that, it increases/decreases the wattage being sent to the solar controller.

Grumpy_G

The ratings for solar panels are done with very favorable parameters that are kinda unrealistic. I recently came across a data sheet that listed STC (standard test conditions) and NOC (nominal operating conditions). Differences: 25C vs 46C temperature, 1000W/m2 vs 800 W/m2 solar irradiance resulting in 128W vs 100W output. Solar cells are semiconductors and as all semiconductors perform worse as they get hotter. I've never seen more ~130W from my 200W rated panel either. 

donmontalvo

It gets stranger with curved solar panels, like those mounted on T@B rooftops.

AnOldUR

The most our 310W panel will get us is into the mid to low two hundreds with good sun. But it was still worth the upgrade. The most I saw from the factory panel was maybe 80W. An upcoming project is to move the controller from the factory wheel well position to the front box close to the batteries. I'm hoping that will improve performance.  

donmontalvo

A buddy told me to Google "Lambert's Cosine Law and solar panels":

elbolillo

Please post the settings you are using. I have a 220w suitcase panel that I use with a 30' cable and have always had very good charging numbers.