Solar Panel Wiring and Connectors

[DuneElliot]

I have just finished installing 4 100W Renogy Eclipse solar panels on the roof. They are about 6ft above my battery compartment. (See photo)

I do not want to wire them in series.

I also have a Renogy 40A MPPT charge controller, and the wires to run from the roof to the battery compartment.

With the above information in mind, would it be better to do a parallel or a series/parallel set-up?

I understand the concept of how to hook the panels in parallel but not sure what connectors I need although GotSmart did send a link a LONG time ago (can't find the PM now).

I have zero comprehension on how I should hook them all together, or what connectors I need, if I choose to go with series/parallel.

Can someone walk me through step-by-step on how to achieve both of these set-ups with a link or two to exactly what I need to order for connections. This is all new to me although I understand basic electrical systems.

(If anyone who knows how to do this happens to be in Wyoming over the next month and would want to come guide me through this let me know).

 

[John61CT]

What oc voltage are the panels, and what is the max voltage the SC will accept?

 

[tx2sturgis]

(If anyone who knows how to do this happens to be in Wyoming over the next month and would want to come guide me through this let me know).

I will be in central Wyoming for the solar eclipse around the 19th to the 22nd and sure,  I'll have 12 beers and a couple shots of Fireball Whisky and then climb up there and see what I can mess up...

 

[DuneElliot]

I called Renogy and they are sending me some connectors for S/P set-up. From there it'll be one wiring step at a time. It seems overwhelming when looking at the whole thing but tackling one thing at a time, one step every few days it doesn't seem so bad.

 

[Optimistic Paranoid]

OK, so I looked at Renogy's site and pulled the specs on one of their 100 watt panels.  Open circuit voltage is 22.5 volts and short circuit current is 5.75 amps.

So if you wire them in parallel, the solar controller will see 22.5 volts, and (4x5.75=) 22 amps.

If you wire them in series, the solar controller will see (4x22.5=) 90 volts and 5.75 amps.

If you wire them in series parallel, the solar controller will see (2x22.5=) 45 volts and (2x5.75=) 11 amps.

Bottom line is, what exactly can your controller handle by way of volts and amps?

You COULD wire them in parallel without any special connectors, you would either have eight wires (4 positive and 4 negative) going into a combiner box on the roof, or eight wires going through the roof to positive and negative buss bars inside that would then feed the controller.

Or you could use a pair of these to combine 4 wires into one:

https://www.amazon.com/Agile-shop-E...41&sr=8-2-spons&keywords=mc4+connectors&psc=1

 

[DuneElliot]

Okay, this is a lot less complicated than I thought...but that also has to do with the fact that I didn't have to move inverters and battery monitor systems like I thought I was going to have to do. Charge controller is mounted and the controller to battery wiring has been run...just need to connect the two but it's getting too hot out there to be enjoyable and work.

Now I'm waiting on connectors from Renogy and can then finish hooking up the system. And yes, I know to attach the batteries first!

 

[regis101]

So what wiring method did you decide upon and why. With the three given scenarios, I suppose it all depends on how fast you need to replenish the batteries with daily Ah load taken into account.
My newbie solar ways with a smaller 100-200 watt system and an MPPT has me doing the series thing.

 

[DuneElliot]

400W system and went with the Series/Parallel route and once I figured out how it was done it was very simple. I think it is a good compromise especially as I will likely add a couple more panels in the near future.

 

[regis101]

Sounds like you're all over it. Kudos

 

[John61CT]

If you wire them in series parallel, the solar controller will see (2x22.5=) 45 volts and (2x5.75=) 11 amps

Yes, what you want if MPPT, needs to be well above nominal (16-18V) for efficiency.

If PWM then parallel.

Test output watts total before installing and you'll see the difference.

Report back please.

 

[GotSmart]

Seriously.  Unless you are using a extremely large amount of power.... Series or parallel does not matter.  With that system series is best. 

 The controllers can handle it no problems.  Those panels can take partial shading without shutting down everything. The second dawn starts to break you will see power coming into the batteries.  

 The Commander and MT-50 readout will help you decide if you are unsure.  I printed off the MT-50 manual so I could read it.  (getting hard to read 1 point type.)  So simple anyone could set it up.  Plug and play.  

 

[regis101]

Not to drift off topic.  Not to beat a dead horse.  It just seems that the common theme, as I interpret it with my novice level of edumacation,  is that if one has a PMW then you will be in parallel and if using MPPT it works more efficiently ( key word) in series but can be parallel or series-parallel.  

 I will soon be doing my own experimentation with up to 320 Watts of panels and using an MPPT.  I am leaning , with my application, toward series due to placement, size, and distance of the panel(s) from the vehicle.  Some vehicle mounted, some portable.
I'm sure that If I was none the wiser I wouldn't know the difference as long as the batteries get what they want and need.  
Am I close?

 

[GotSmart]

I just use the KISS method.

The modern panels can pass power through even if partially shaded.  

Call the panel tech line, and ask questions.  

That is why I have used Renogy, exclusively.  Once set up, all you need to do is keep the panels clean.

Just remember. 

Panels are ALWAYS connected last and disconnected first. 

Others here claim it makes no difference.  Fry components in the boondocks and you will be slightly .... Pissed off.

As well as SOL.   :dodgy:

 

[regis101]

I'm using Renogy components

 

[GotSmart]

Then you have it made.