Here's a REAL beginner question

[eddie1261]

I am about ready to mount the panel on my trailer and connect everything. I have read the answer to this question on other forums many times and if I ask 10 people, 5 say one way and 5 say the opposite.

What order do I connect things?

The way I THINK I am supposed to do it is battery first, MC4s into the panel with the CC side not connected, then panel NEGATIVE, then panel POSITIVE. No matter how I do it, half of the people say I am wrong. (Kind of like trying to explain something to a wife.)

In any case, the panel will have the packaging cardboard taped to it and during the whole install process it will NOT be harvesting sunlight. i may even pull it into the garage to do this, but that may be overkill if I keep it covered.

Do I have it right? Start at the battery and work up. and connect the positive to the charge controller last? Then take the cardboard off the panel?

 

[Rider]

If you were connecting a battery in a car, you always connect the positive battery leg first. That way if you accidentally strike the car frame with the wrench while attaching the postive lug, there is no path to the frame and no welding. If you attach the negative first, then the positive and strike the frame with the wrench, big sparks.

In the case of the solar panels, it's usually such low current it really makes no difference which one you tie first, but I always follow my car battery example.

 

[eddie1261]

2 things at play with the battery. 1 is, as you said, it's very low voltage. 2, there are no wrenches involved with the Ruixu battery. It's hand screwed lugs. 3, and here's where the rub comes in, in Will's video showing the MPP 12V all in one (which I have) he shows connecting the battery negative to the controller first.

See why I get confused? Here are 2 people who have knowledge at a level that I trust, telling me opposite things.

I have gone so far on this thing that I took an old truck inner tube and created covers for the battery terminals. I got it to use as vibration/chafing absorbing material for something else and I have a bunch of the rubber left. Even though there won't be tools or metal anywhere near the battery, I am anal that way.

 

[Rider]

I am anal that way.

Yeah. Way too. No need to get spooled up over it. The only thing you really want to do is make sure the battery is connected and the SCC is on before connecting the panels.

To confuse you even more.... I read many times where you shouldn't connect/disconnect panels wires when volts/amps are present. So I installed a switch. Throw the switch, quick connect/disconnect, no arcing, no issues. BUT, I wired the switch on the positive panel leg.

 

[eddie1261]

Just thinking about the MPP and it has an on/off switch on it. I can just leave it off when I connect the panel. This is where I say

 

[MrNatural22]

Just thinking about the MPP and it has an on/off switch on it. I can just leave it off when I connect the panel. This is where I say

View attachment 725

The switch on the MPP only turns the inverter portion off and on. The MPPT CC still operates with the switch off. ?

 

[eddie1261]

The switch on the MPP only turns the inverter portion off and on. The MPPT CC still operates with the switch off. ?

Interesting.


This page of the manual would indicate that the entire unit is switchable.

 

[MrNatural22]

Interesting.

View attachment 731
This page of the manual would indicate that the entire unit is switchable.

Not sure which model your using. I have the pip 812-12v 800w model on that one the switch is only for inverter on/off. Different models may use the switch for entire unit.

 

[Will Prowse]

Most things are negative ground, so positive first is smart. I love negative first to bypass ocpd to charge the capacitors. For this small of a unit and at that low of a voltage, it probably doesnt matter. But positive first is what most go with due to automotive battery protocol.

And as always, battery connection first, SCC second. But I have actually tested connecting 8 different SCC's to a 60 voc array and none of them were destroyed. I made a video about it but it was boring, so never posted it.

And yes, the SCC is still active when mpp inverter switch is "off".

I am installing 2 of these this morning for my shed system. I love them. 2x 48v units hehe :D

 

[eddie1261]

And yes, the SCC is still active when mpp inverter switch is "off".

Not that I don't trust or believe you, but I have to test that once I get things installed. The language in the manual is confusing. It says "Simply press on/off switch to turn on the unit." So if the charge controller is active all the time, what does that on/off switch actually turn on and off? Someone said "the inverter". I have installed the Ac in and out wiring, but I will have nothing running 110v in my trailer and I just put that wire in because it's there..

And as to the sparking when the unit's capacitors get charged, if I connect battery positive to MPP rather than negative first does that sparking not happen?

This whole conversation started because I didn't know what state everything needs to be in when I connect the panel to the MPP. In your video on the 12V MPP you connected battery negative first. Then when you connected the PV you connected negative first. I don't know the physics behind why connecting the PV in the right or wrong order matters. Please elaborate. This seems to be one of those questions that if I ask 10 people, 5 will say positive first and 5 will save negative first.

Thanks.

 

[eddie1261]

So I installed a switch. Throw the switch, quick connect/disconnect, no arcing, no issues. BUT, I wired the switch on the positive panel leg.

So PV negative to CC, PV positive to a switch, switch to CC positive. That allows me to connect the PV to a dead connection point and then kick it over to live.

 

[Will Prowse]

Oh I know this because I use them everyday. Scc is active all the time whether on/off switch is active or not. The switch is only for the inverter like another member said earlier.

 

[Will Prowse]

Not that I don't trust or believe you, but I have to test that once I get things installed. The language in the manual is confusing. It says "Simply press on/off switch to turn on the unit." So if the charge controller is active all the time, what does that on/off switch actually turn on and off? Someone said "the inverter". I have installed the Ac in and out wiring, but I will have nothing running 110v in my trailer and I just put that wire in because it's there..

And as to the sparking when the unit's capacitors get charged, if I connect battery positive to MPP rather than negative first does that sparking not happen?

This whole conversation started because I didn't know what state everything needs to be in when I connect the panel to the MPP. In your video on the 12V MPP you connected battery negative first. Then when you connected the PV you connected negative first. I don't know the physics behind why connecting the PV in the right or wrong order matters. Please elaborate. This seems to be one of those questions that if I ask 10 people, 5 will say positive first and 5 will save negative first.

Thanks.

Sparking will always happen regardless of completing circuit on positive or negative side. Electricity doesn't care where you connect it in the circuit. You can get rid of spark by running resistor in series. I do this with my large systems, and did it this morning. No spark. Easy peasy haha

 

[Will Prowse]

Not that I don't trust or believe you, but I have to test that once I get things installed. The language in the manual is confusing. It says "Simply press on/off switch to turn on the unit." So if the charge controller is active all the time, what does that on/off switch actually turn on and off? Someone said "the inverter". I have installed the Ac in and out wiring, but I will have nothing running 110v in my trailer and I just put that wire in because it's there..

And as to the sparking when the unit's capacitors get charged, if I connect battery positive to MPP rather than negative first does that sparking not happen?

This whole conversation started because I didn't know what state everything needs to be in when I connect the panel to the MPP. In your video on the 12V MPP you connected battery negative first. Then when you connected the PV you connected negative first. I don't know the physics behind why connecting the PV in the right or wrong order matters. Please elaborate. This seems to be one of those questions that if I ask 10 people, 5 will say positive first and 5 will save negative first.

Thanks.

And for the last bit, there is no need for opinions. I can present an argument why I need to connect negative or positive depending on application. That's all. Everyone can find a way to do it so that either method is smart or safe. There is no opinions on this topic. It has to do with what is logical for the specified application and that's it.

Maybe you're not understanding how these circuits work. I would suggest getting a circuit design book and research the fundamentals. Because either method works depending on what you are doing. There were even some positive ground car systems decades ago that would need negative wire first. Like I said earlier, depends on application. I said my reasoning for bypassing ocpd because it can be triggered or damaged. That's just me. Positive first works well if negative ground stuff is everywhere. I don't ground much to chassis for low volt mobile systems, so it doesn't matter. Really depends on what you are doing

 

[Ulmo]

Is it effective or worthwhile to wire in a switch? That would add to the expense, complication, etc. But it would supposedly be designed to handle the spark. I guess it doesn't matter which side it's on if you're not grounding a leg, and if you are grounding a leg, then I suppose you put it on the other leg.