Confused

[Damon]

Hello all,
Been lurking on this forum for about a month after learning about it, and learning a great deal.
I am putting together a system for my RV (motorhome). I thought I had it all figured out and ordered most of the parts. I will not be getting my panels for a few more weeks, but have ordered the parts to get the install started. I will be getting 2 x 340w panels (Sunpower P17). The info on them is: VOC=51.3v, VMP=42.5v, ISC=8.00a, max pwr current=8.52a, max system volt=1500. I plan to parallel them.
My question is on the MPPT I ordered. I ordered a Tracer 3210AN (30amp), in it's specs., it states: Max PV Open Circuit Volts= 100v, Max PV Input Power=390w/12v.
The Max PV Opern Circuit Volts should not be a problem for this MPPT. I do not understand the Max PV Input Power (390w/12v).
Have I picked the right MPPT for this set up?
I will be charging a battery bank of 6 x 6v FLA GCs, in series/parallel for 12 volts at a total of 696ah.

 

[A J]

Hello Damon;
Just so i am right?
2X 340W in parallel would be 680W your controller is 360W @ 12V with a max of 390W!
With my controller the extra Watts is what they call hyperVOC, they claim this is for extra cold conditions where the ice snow on the panel with a blast of sun forces the voltage to go hyper this is temporary not for prolonged use.
Parallel is doubling the AMPS not the volts eg The MAX AMPS of 8.52a X 2 = 17.04a, VOC 51.3 and VMP 42.5
Sires is doubling VOLTS not amps eg MAX AMPS 8.52a, VOC 51.3 X 2 = 102.6V

Some one will correct me if I am WRONG.

The underline is a key to me that something is a miss.

 

[Damon]

Hey AJ,
You may have answered my question. What was confusing me was the (390w/12v). So the "/" means "@". I was dividing and getting and getting 32.5a lol
So, since I am building a 12 volt system, the MPPT I ordered will not handle the panels in parallel.
Which means I need a second MPPT. Right?

 

[A J]

Well Damon; up to you mate...
1, you could hook up both panels and the overload will kick in or fry the controller.
2 , get two controllers.
3, size the panels to the controller, seeming you have't got them yet 360 / 2 is 180.

Drum roll what will you pick door 1, 2 or 3 or take the fourth?

I my self have had problems with many of the aspects of this and doing it my self with no help apart from the internet was and is frustrating, confusing until Will made this forum so people can ask the question and get a idea of what is what.
Happy to provide the answer that may be. Enjoy your new solar investment and the joy of doing it your self.

 

[Damon]

Thanks for the help AJ,
Yes, this forum is a great place to get info on solar. I'm just not used to some of the terminology.
I am going to take the fourth for now and just get 1 panel. My original plan was 400w anyway. If it turns out I need MORE POWER then I can always add to it later.

 

[A J]

Very wise choice.
The terminology can be a head spin, with lots of reading to the point of a head ache, asking questions on forums like this HELPS.
One thing I will say is I learnt to size your max load + some extra then plan how to match it with "lots of room to spare".
Top of the day to you .

 

[SolarRat]

That controller will handle both panels, but in series only, for a 24v system. Do you already have an inverter? If not, I'd do the 24v system for many reasons.

You didn't say what battery bank you'll be using. One of those panels could charge the battery at 28 amps @ 12v...you should be fine unless we are talking about only a single 12v lead acid.

 

[A J]

Hi SolarRat;
Yea Damon did
"I will be charging a battery bank of 6 x 6v FLA GCs, in series/parallel for 12 volts at a total of 696ah "
and
"I thought I had it all figured out and ordered most of the parts"

Damon could reconfigure the batts to produce 24V and will lose the 696Ah! He did order most of the parts, what I don't know, Inverter?...
We will see?
Damon your thoughts?

 

[Damon]

I am using the existing charger/inverter 2500w at 12vdc. It is original equipment. I really don't intend to use it much. I just want to be able to boonedock for extended periods. Lights, water pump, charge electronics, fans and maybe some TV if stuck indoors. The RV does have a generator. But who wants to listen to it?

 

[Damon]

And by the way, if you all are wondering. I did seriously over size my battery bank, based on what my daily needs "should" be. Used the 50% discharge rule I learned from this and other resources.

 

[A J]

Yea I was just scribbling on my table 696ah X 12V = 8,352Wh, I thought I was bad with 520Ah X 12V = 6,240Wh well done

 

[Supervstech]

Hey AJ,
You may have answered my question. What was confusing me was the (390w/12v). So the "/" means "@". I was dividing and getting and getting 32.5a lol
So, since I am building a 12 volt system, the MPPT I ordered will not handle the panels in parallel.
Which means I need a second MPPT. Right?

You are correct.
This is saying, it can only handle 390watts at 12v or 32.5 amps max...
At 24v, it could handle the higher wattages...

 

[Damon]

Thank you Supervstech for the reply and confirmation.
I "think" I am set now.
What a great forum Will has created.

 

[A J]

You are correct.
This is saying, it can only handle 390watts at 12v or 32.5 amps max...
At 24v, it could handle the higher wattages...

Nailed it...
I said someone would correct me or in this case straighten things out...
Thank you Supervstech for the clarification and Top of the day to you .

Damon you think your set? You know where to come when thoughts escape you!