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Old 03-01-2013, 12:27 PM   #1
Alwims
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My solar system is complete, maybe.

I didn't have time to take pictures, but will tomorrow. I just added 2 more 68 watt Unisolar panels to the roof and they ain't no more room up there. I've got 7 panels total for 596 watts. 5 12 volt 68w panels and 2 24 volt 128w panels. I'm running the oddball 68w panel parallel to one of the 128 watt panels. I'm running 2 68w in series to make 24 volt so now I'm running 4 pairs of 24 volt to the MPPT controller. In other words, (2 x 12 volt-68w series = 24 volt - 136w), (2 x 12 volt-68w series = 24 volt - 136w), (1 x 24 volt = 24 volt - 128w), (1 x 24 volt = 24 volt - 128w) As explained the extra 12 volt 68w in parallel with one of the 128w panels.

OK, now that I've completely confused you, my question, Should I run 24 volt, 36 volt or 48 volt to the charge controller? As some of you know I'm running the Morningstar Tristar 60 amp MPPT controller.
 
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Old 03-01-2013, 02:40 PM   #2
7.3Ford
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Alan,

You want to put the odd ball in series with the other three sets in parallel.

The following in Parallel 128 + 128 + (two 68 in series) (three 24V sets in parallel.

Then put the last 68 in series with the three parallel groups, which will get you 36V.

If you try to put a 12V in parallel with 24V, it will pull down the 24V panels to 12-16V and you will loose most of you power.

Everything in parallel must be same voltage.

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Old 03-01-2013, 03:03 PM   #3
Tom S.
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Your Solar System is complete?

How many planets do you have?
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Old 03-01-2013, 04:24 PM   #4
Alwims
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Quote:
quote:Originally posted by Alwims

Quote:
quote:Originally posted by 7.3Ford

Alan,

You want to put the odd ball in series with the other three sets in parallel.

The following in Parallel 128 + 128 + (two 68 in series) (three 24V sets in parallel.

Then put the last 68 in series with the three parallel groups, which will get you 36V.

If you try to put a 12V in parallel with 24V, it will pull down the 24V panels to 12-16V and you will loose most of you power.

Everything in parallel must be same voltage.

Didn't realize that although I think you may have told that to me before. How 'bout this,(1),128w-24v + 68w-12v = 36 volts, (2),128w-24v + 68w-12v = 36 volts, (3),68w-12v + 68w-12v + 68w-12v = 36 volts. All 3 sets in parallel to the MPPT.

I really should get more sleep before I try to do this stuff, duh.
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Old 03-01-2013, 05:05 PM   #5
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Quote:
quote:Originally posted by Alwims
Didn't realize that although I think you may have told that to me before. How 'bout this,(1),128w-24v + 68w-12v = 36 volts, (2),128w-24v + 68w-12v = 36 volts, (3),68w-12v + 68w-12v + 68w-12v = 36 volts. All 3 sets in parallel to the MPPT.

I really should get more sleep before I try to do this stuff, duh.
Alan,

That will work as well, maybe even better. Remember anything in parallel must be same voltage.
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Old 03-02-2013, 03:13 AM   #6
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John, thanks so much for all your help. Without you and Greg I probably would have burned our Montana to the ground by now. As you can tell, I'm a jack of all trades and a master of none. I'm not afraid to tackle any job, but I have been known to get in over my head before and I came close with all this. Thanks again.
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Old 03-02-2013, 03:20 AM   #7
Alwims
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Quote:
quote:Originally posted by Tom S.

Your Solar System is complete?

How many planets do you have?
Tom, I'm not ignoring you, I'm just trying to figure out a witty answer for ya, but my brain is fried over my solar system. I may have touched too many live wires during all this. Believe me when I say, they is juice in them solar panels and they will shock ya. Ask me how I know.
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Old 03-02-2013, 03:34 AM   #8
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Quote:
quote:Originally posted by Tom S.

Your Solar System is complete?

How many planets do you have?
Tom,

I think he said, he has 7 panels (596 Watts) unless my math is wrong.

He just wanted to show me up, since I only have 6 panels (544 Watts).
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Old 03-02-2013, 03:50 AM   #9
Alwims
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Quote:
quote:Originally posted by 7.3Ford

Quote:
quote:Originally posted by Tom S.

Your Solar System is complete?

How many planets do you have?
Tom,

I think he said, he has 7 panels (596 Watts) unless my math is wrong.

He just wanted to show me up, since I only have 6 panels (544 Watts).
Heck, I've been trying to figure out how well the panels would work if I wrapped both air conditioners with them. Then I'd be king of the flat panels. That dang Greg still has me beat with 636 watts I believe. I started out trying to do this on a budget which is why I ended up with 2 128w panels instead of 2 144w panels.

A word to the wise, forget trying to go solar on the cheap. You will regret it and end up spending more in the long run. Ask me how I know this.

And Tom, the Planets were way out of line for me which is why I had to build my own Solar System.
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Old 03-02-2013, 05:01 AM   #10
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I was wrong in my wording of how I wired things yesterday. I said I wired the "oddball" panel in parallel I should have said "in series" with the 4 24 volt parallel strings as per Greg's instructions before I added these 2 new 68w panels. Being the dunce I am or a better term, Missouri Hillbilly, I got my terms mixed up. I decided to leave it alone and see what kind of numbers I get.

Since this is an amps to the battery game, I figured 4 24 volt strings would add up amps faster than 3 36 volt strings.

I know watching the numbers is like watching paint dry, but I'm amazed at my numbers so far. Here is a screen shot at 10:45am on a nice sunny day the 2nd of March.

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Old 03-02-2013, 05:06 AM   #11
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Here is what 15 minutes later looks like.

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Old 03-02-2013, 05:54 AM   #12
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Alan,

Since you have 3 strings - the NEC code requires that each string has circuit protection.

The reason for this is if there is a panel fault, three or more strings could generate enough current to exceed the current capacity of the conductors. Two or less strings can't.

If you refer back to my posts and electrical wiring diagram - you'll see that mentioned the circuit breakers being required. I brought all 3 positive leads down to a breaker box - thru a 10amp breaker on each - then combined them before going into the controller.

I've posted the link back to that post HERE.

An added benefit to the breakers is that you can isolate the bad string and keep on running.

Hopefully you've already done this and I'm not raining on your parade.

I have some other suggestions regarding what panels to tie together but I'll put that on a second post with a hand drawn diagram in a few minutes.
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Old 03-02-2013, 06:07 AM   #13
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I've got 4 24 volt strings as of now. I do have them connected to 1 30amp breaker before the controller, not 4 as you said. I look forward to your diagram. Thanks again.
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Old 03-02-2013, 06:15 AM   #14
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You will exceed 30 amps going into the controller with that set up.

let me go back to your post and total up each strings amperage and I'll get back to you.
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Old 03-02-2013, 06:24 AM   #15
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Now I'm really confused.
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Old 03-02-2013, 06:28 AM   #16
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Alan,

Ok - I tried to draw something up but looking at my old post you can use the two pictures of the roof to follow along.

Looking at the first picture of the roof (trees and street in the distance) you are looking towards the front of the trailer. The curb side would be on the right.

Looking at the second picture of the roof (house and boats in view) you are looking towards the back (curb side would be on the left)

If you notice - drawing an imaginary line down the center of the trailer - more panels are on the curb side. The curb side panels (4 of them) are wired into two of the strings. The street side is the third string.

The reason (beside the available real estate for placement on the roof) is due to the curve of the roof.

With the sun lower in the sky i've found that positioning the rig so that mid day sun hits more towards the curb side - those panels are facing more directly into the sun and I get a higher yield earlier in the day on more panels.

As the sun starts to lower it is directly south. Right now I'm Boondocking at Roosevelt Lake in Arizona and the sun is at 90 degrees off the curb side right now and its 1130 here. Solar Noon here is at 1336 - so the sun will be at about the ppm position on the trailer when it is at its highest.

I'm getting over 210 amp hours per day with this orientation.

Since the panels wont tilt - but the roof has a tilt - I tried to take advantage of that when I decided what panels to wire into each string. Then I position the trailer to try and take advantage of that tilt.

When I was at the circle in Q I was assigned a space pointing due south. I was getting about 50 less AH per day. Now I'm pointed about 240 degrees.

Hope this doesn't confuse.
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Old 03-02-2013, 06:29 AM   #17
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Whoop sorry I wasn't thinking... you wont exceed 30 amps... the 30 amps will be on the 12v side.
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Old 03-02-2013, 07:06 AM   #18
Alwims
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Not confused at all now. Thanks for the explanation. My AH's are a little low as I thought I had something seriously wired wrong so I shut off everything last night and didn't turn it back on until 9:15am this morning. Here is where I'm at now at around 1pm, central time. The numbers were a little higher, but a cloud rolled over for a bit.

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Old 03-02-2013, 07:09 AM   #19
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Sorry about giving you the heart attack.

I just downloaded the specs for the 128s

If you go with the last set up... the 3 36v strings. (actually looks like 49.5v each string - 33v + 16.5v) It looks like You will want an 8amp dc fuse or circuit breaker on the positive lead of each string. (3 8 amp fuses)

If you look at the spec sheet for your panels you'll see a spec "Max Series Fuse Rating - 10 amps" for the pvl-68 but 8 amps for the pvl-128 This is the fuse I'm talking about.

Again - if you had a short in a panel - one or two strings cant produce enough current. But 3 or more could produce enough current to start a fire in the shorted panel so the 10a fuse protects against that.

I noticed that the screen shot that you posted showed that the Tristar was in MPPT mode. That is bulk charging. Your battery voltage was 13.something.

Bear in mind that when your battery gets up to about 14.7 isn (depending upon your settings and the temperature) the controller will go into absorb mode. You'll see the watts drop off. That's because now the controller is just maintaining a constant voltage to finish topping off the batteries - not trying to give them all its got.

I've found out here boon docking - at the later part of the day when my batteries are almost done charging and I am in absorption - that's a good time to take advantage of the extra panel power that is not being used to do stuff like charge computers, and any other stuff that can utilize the power now rather than later on at night when it will be coming out of the batteries instead.

In absorption I might be just showing say 150watts. But then I turn on the inverter and start charging up the computers, phones, iPads and all that stuff and the meter might show the panels putting out 300w and we are still in absorption.

In MPPT mode the panels are giving you all they got.
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Old 03-02-2013, 07:18 AM   #20
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You might have been low because the controller went into absorption.

396 w is pretty good output depending on how strong the sun is.

the best that I've seen thus far is 475w and I'm further south, positioned perfect, Clear in-the-middle-of-nowhere-Arizona air, and not a cloud for 500 miles. My history data shows 975w yesterday as pmax but I don't know where the hell that comes from :-) It's about an hour from solar noon here and right now I'm putting out about 465w so maybe today I'll best my record. Each day the sun gets a little higher the pmax does too.

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