20x32 A frame cabin Central KY

[John Raabe]

EaglesSJ


Thanks for the update and great photos. You sure have a lot of life going on there!

[EaglesSJ]

Ok guys so Im needing some help wiring up some solar panels. I bought 8 230w sharp panels (ND-u230Q1) to be exact. They are listed as 24v panels. I also have my 6 Kyocera 210w panels which are 26.6v maximum output.

I have a flex max 80 charge controller and will be going to a 48v system via my new Outback vfx3648 inverter. So Im thinking that I wire up two sets of four 230w sharps in series. This gives me a total of 120v dc maximum output at 17amps (each set being 120v 8.48amps)

I run these two sets into my combiner box. Each set on its own 15amp breaker. I leave my existing panel setup as is. Three 26.6v panels wired in series for a total of 79.8v at 7.9amps per set (79.8v 16amp total for both sets) Each again being on its own 15amp breaker is it currently is.

Am I going about this the right way? Or is there a better way to wire these items up?

[EaglesSJ]

After further reading I see that I cannot do that large of a voltage difference. So what if I buy 1 more sharp 230 bringing my total up to 9. Then I could wire 3 in series for a total of 90 volts. My other array will be 79.8 volts or 80v for arguments sake. This will leave me with a 10vdc difference going into the combiner box. Will this be a problem?

[CjAl]

how about two of each in series? or is that not a good idea?

[EaglesSJ]

That doesnt give me enough power to fully charge my batteries. 26.6v x2 =53.2v I need at least 60 volts available to me.

[CjAl]

i meant two of your old ones and two of your new ones in a single series circuit. then both would be.equal. i just wasnt sure if you could mix the panels

[EaglesSJ]

Lol funny you should say that because I was just about to suggest that  I wire 2 of my old in series with 3 new giving me a total voltage of 143.2vdv and around 7.7amps

I can wire it that way because the kyoceras are 7.9amp and the sharps are 7.61amp which by my calculations are within 4% of each other and the voltage is under the 150vdvc limit set by outback

Here are links to specs if anyone wants to check my calcs

http://www.solardesigntool.com/components/module-panel-solar/Kyocera/KD210GX-LPU/specification-data-sheet.html;jsessionid=5432CC1B1790340ED8659928298DE780

http://www.ecodirect.com/Sharp-ND-U230C1-230-Watt-24-Volt-p/sharp-nd-u230q1.htm

[EaglesSJ]

i meant two of your old ones and two of your new ones in a single series circuit. then both would be.equal. i just wasnt sure if you could mix the panels

I cant do 2 and 2 because i have 8 of 1 and 6 of the other.

[CjAl]

sorry i saw 8 and thought that was.total now. i am driving, missed the finer details but you got my point.


damn. thats a huge array

[CjAl]

if you did 2+3 then what would you do with the remaining 4 sharps?

too bad you dont have 6 and 9, that would put you at 23 amps, 143 v with three banks runnng parralel

[EaglesSJ]

if you did 2+3 then what would you do with the remaining 4 sharps?

too bad you dont have 6 and 9, that would put you at 23 amps, 143 v with three banks runnng parralel

I think you missed something. I will have 9 sharps total and my current 6 kyoceras my array will look like this:

KSSSK
KSSSK
KSSSK

I am doing that to keep the array aesthetically balanced.

Wiring each string in series will provide 143.2 v and around 7.7 amps for a total of 1102watts per string, or 3306 total array size

[CjAl]

ya i swapped them around in my head. im just going to shut up now, i should know better then to run numbers in my head on 2hr sleep.

[CjAl]

btw i am totally envious of your setup. i would kill to take that meter off my house. in southeast tx you can just imagine how much power i.use for just air conditioning

[EaglesSJ]

ya i swapped them around in my head. im just going to shut up now, i should know better then to run numbers in my head on 2hr sleep.

lol actually having someone to sit here and work it through with really helped. So thanks. Do you not run on PV? I thought when I checked out your thread I seen something about that in there?

[CjAl]

im not running anything right now. i have to get the cabin built first, just got half the.pire done last weekend hopefully finish them monday when i get home. i have no power at the site i run my tools off a 2500w  power invertor hooked to either the four batteries on.my semi or the battery in my suburban. if i use the burb i have to run it the whole time, the truck can run app day without charging.

i plan to start a pv setup and mabey wind too since my place is the high spot in the area altho thats not saying much.

due to our demand for ac i think i am.going to put radiant in the floor then i will dig a half dozen or so shallow wells to run the pipe down. hopefully that will help lessen the ac, plus in winter i can redirect it to a solar water heater to heat the house. of course we dont need a whole lot of heat, mid 40's is real cold for us

[AdironDoc]

i have to get the cabin built first,

I practiced positive visualization...  I imagined my cabin built, dropped tons of money on stuff like a wood stove, then simply had the cabin built around it!  I'm quite sure I'm not the only one!

[CjAl]

lol, i hear ya. mine was supposed to be dried in by now but i blew up a semi and had to.buy another, kind of set me back to say the least. my building permit is actuwlly expired now, it was supposed to.be dried in by this time last month and i havnt started the deck yet. im a 350lb truck driver from WI, trust me i.didnt.plan to be pouring concrete and building in the middle of tx summer.

[EaglesSJ]

Ok so apparently the flexmax 80 can only handle 150vdc of voc NOT isc. So here is the shape Im in. I have 9 sharp 230s with a  37.1 VOC and 6 kyoceras with a 33.2 VOC.

I currently have 3 sharps and 2 kyoceras wired in series. That puts my VOC too high for the CC. I would like to wire these in a way that I didnt have to buy another charge controller. Even if it means losing a little power. I dont want to sink another $700 in another flexmax controller.

[PorkChopsMmm]

Have you tried using this string sizing tool from Outback? It has helped me figure some things out. I don't think your issue is going to be loosing power -- it will be frying your CC if you exceed certain ratings, especially this winter when the panels are cold and get hit with the bright morning sun.

http://www.outbackpower.com/resources/string_sizing_tool/

[Squirl]

Don't forget with VOC you have to temperature correct for winter and also NEC requires a 25% safety margin.  Mountain Don did a pretty good guide in the off grid power topic a while ago.  At my latitude, stringing 3 "24v" panels in a row failed most charge controllers (196 volts with temp and safety corrections) .  You are a bit south, but still get snow in the winter.  You are probably  within the specs to string three panels, but I'd be willing to bet dimes to donuts that more than three would fail most electrical guidelines.

37.1 VOC * 3 panels = 111.3 volts * 1.25 NEC margin = 139.125 volts * 1.15 estimated winter correction (you would need to calculate actual correction) = 160 Volts.

[Greenwood]

I don't know much about solar power but you could put 5 strings of sharp-kycera-sharp, you would need to buy a nother sharp panel and not use one of the kyoceras you already have ( I think this is net cheaper then buying a new controller).  That would give you 107.4V per string with a 25% safety margin and winter adjustment of 10% you would come in at 147.7V.

[Squirl]

2 Sharps and 1 kyoceras will give you 4 solar strings of 107.4 volts and 1 string of 1 sharp and 2 kyoceras at 103.5 volts.  Check you manual or with outback if the CC can handle two different input voltages like that.  My recollection was that MPPT controllers don't handle different input voltages well.

If were stuck with the extra 3 panels, I would consider wiring them two in parrallel up to a low amperage 48v pwm controller and selling the third.  Or spending a few dollars extra and getting a low amperage mppt controller.

[Squirl]

Calculating winter temp correction.

Take the coldest ever recorded temperature for your location.  Subtract that from the temperature the Voc is rated at on the panels.  Take the answer and multiply it times the temperature coefficient from the panels.

For the sharps.

Panel Voc temp 25 degrees C. 
Coldest temp ever for Lexington (central KY) -21 degrees F. (-29.44 C)
25--29.44 = 54.44 degrees C
Sharp panel temperature coefficient -.36%/ degree C
54.44 * .36 = 19.6
Adjustment factor for Sharp panels at Lexington KY 1.20

[EaglesSJ]

I guess Im just going to sell my Kyocera Panels and buy more sharp 230s.

[EaglesSJ]

Here are our panels for now. Mounted on a galvanized pipe rack with enough bracing to look like a giant erector set. Running a 15k BTU A/C and still charging the batteries is awesome