Solar Tracker, Kyocera 135w, U.S Battery Bank

BilljustBill · November 2010

I have been working toward a 2kw solar array for the last year. In addition to China made panels and several used Seimens' panels, I have slowly aquired 8 new Kyocera 135w panels, Redroc tracker modules, and the mounts & actuactors from a large 12' C-band satellite dish and two 8' dish mounts. Knowing my electrical needs exceed my budget, I'll make do with what KWH I can generate until I can add more panels....

Because of pricing here in Texas, the best battery pricing has been with U.S. Battery for the L-16 re with 403 amp/hr at the 20hr. rating. It will be wired for a 48v system.
With the heavy-duty satellite dish's mount on a 6" diameter, 8' pole, I want wire 10 Kyocera 135 w panels in two 5-panel strings and use a MPPT controller.

Is the 5-panel approach reasonable? To go that route, below is what I think I need to get this tracker array and two smaller tracker's up and generating before December 31st.

Two more Kyocera 135w panels....... $ 800.00
Eight L-16 batteries plus cores..........$2,000.00
MPPT controller..80amp Flexmax........$ 599.00
Mate or Mate II..................................$ 239.00
VFX3648 Outback...............................$1,900.00
Total to finish:....................................$5,538.00.

On my mixed panels, here is how I see I could use them
on the two other tracker mounts I have.
I would use the Tristar 60 PWM controller I already own, for now:

One string of four 100w new China-made panels, plus one used Siemens 120 watt panel equaling 5 panels. 6.20 amps X (17.5) 88v = Max: 620 w

One string of four of the used 75w Siemens panels, plus one new China 90 watt panel, equaling 5 panels. 4.28 amp X (17.5) or 88 v =Max: 376 w

What can you tell me about my approach and what needs changing? Would a 24v battery bank and panel wiring be better in my case?

I want to learn how to attach pictures if you need to see the tracker/dish mounts and future progress using your advice and experience.

Thank you for your experience and help,
Bill

sawmill · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

I use the 360 amp hour version US Battery in a 24 volt bank with 4 of the Kyocera 135's per string. This works fine for 24 volt MPPT charging.

US Battery recommends 2.58 volts per cell for bulk and 2.83 for equalizing.

Since this would equate to 64 volts for bulk and 68 volts for equalization, I wonder if the MPPT advantage would be lost during hot Texas conditions. Perhaps some of the members with a better understanding and knowledge of the MPPT function can chime in.

mike95490 · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

sawmill wrote: »

I use the 360 amp hour version US Battery in a 24 volt bank with 4 of the Kyocera 135's per string. This works fine for 24 volt MPPT charging.

US Battery recommends 2.58 volts per cell for bulk and 2.83 for equalizing.

Since this would equate to 64 volts for bulk and 68 volts for equalization, I wonder if the MPPT advantage would be lost during hot Texas conditions. Perhaps some of the members with a better understanding and knowledge of the MPPT function can chime in.

A 48V bank only needs 62V for EQ !

But, as to MPPT, you configure your array for 70 - 120V, and let the charge controller, in a "transformer like fashion" down convert the extra voltage, to amps while you charge.

sawmill · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

As per the US Battery site they recommend 2.583 for bulk charging. This is equal to 61.92 volts for a 48 volt bank. When the manufacturer was contacted for their equalizing voltage for a 24 volt bank their reply was 34 volts.

Your 62 volt figure is correct for Trojans but we are talking about US Battery. If you have any information or facts that disputes the figures provided by the manufacturer please share them so those of us who are using US Battery can be assured of the correct charging voltages.

niel · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

i don't think sawmill's argument will apply in this case as the op is opting for 5 kc135s in series and it will yield about 88.5vmp.

from the op,
"I want wire 10 Kyocera 135 w panels in two 5-panel strings and use a MPPT controller."

mike95490 · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

Sorry, I was using a SWAG, because I thought your were talking about a 24V bank.
Not many charge controllers will go much beyond 65V, 68V will be tough to get.

If you don't drain your batteries too deeply, and use longer absorb times, that can greatly reduce the need for EQ cycles.

But, bottom line is, the battery Mfg is always right, because they back up their warranty.

BilljustBill · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

niel wrote: »

i don't think sawmill's argument will apply in this case as the op is opting for 5 kc135s in series and it will yield about 88.5vmp.

from the op,
"I want wire 10 Kyocera 135 w panels in two 5-panel strings and use a MPPT controller."

I appreciate everyone's input. I read that Outback's flexmat 80 amp controller has a voltage max of 150v. With the five Kyocera 135's in a string, do you think the over-voltage pm a North Central Texas cold 20-degree and crystal clear day, would ever be a problem running a 48 volt battery bank and Outback's off grid 3648 inverter?

Using a straight series run of eight U.S. L-16 Batteries ( L-16e or L-16re), and the combined volts/amps/watts of the 10 Kyocera and the two other strings of used panels, am I going to be able to fully charge the battery bank? I know there are a lot of what-if's, in how much I'll use and how deep I'll pull-down the batteries, but at the moment, I don't see either of the two to be a problem as the system is first going to support a 1,000sq.ft., insulated, stand-alone hobby building.

Also, to help you understand the rest of my plans, I'm in a clear wind area with a Wind Zone 2 and average of 10mph.... So, I've also started aquiring wiring, a 500 watt DC generator, composite blade sets, and guywire. It will up only about 45 ft, but should add some watts/amps to the battery bank at night and overcast days.

Having put so much time, planning, and now a larger amount of dollars into this solar project, all the help, insight, and experience you and the others can share, as you well know, can help from making costly mistakes. I want this system operational by December 31, to keep Uncle Sam happy and qualify for the tax credits as that money will have gone into paying for this 2+ Kw system.

Thanks again for your help,
Bill

BB. · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

It looks like, using this link, Kyocera 135 panels, you can run between 5 and 6 in a string for a 48 volt battery bank. 6 in series, at 14F would estimate at Voc-Cold at 149 volts...

At 95F and 5 panels, you would be 70 volts Vmp-hot...

-Bill

niel · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

you won't need to worry about the voltage going too high, but to charge l-16s it is generally known that it should be in a range of 5%-13% for charging batteries and the imp of each string will be about 7.63a so for 2 strings it's 15.26a. even adding 10% for mppt would bring it to about 16.8a and you may get more because you are running a higher voltage, but we'll go with the 16.8a. 16.8a/403ah=4.17%. i would add a 3rd string of 5 minimally if not a 4th string of 5 too to properly charge the batteries. if it were a trojan l-16 they would specify a 10% charge rate and you are getting roughly about 2% per string.
i don't know how deeply you'll load your batteries to say if the 2 strings are enough to meet your load requirements, but as you have a large battery bank it will require a large current rate to properly mix it as well as give it a proper charge. if loads are light enough that you think the wattage of 2 strings will work then i would still recommend at least getting the charge rate over 5% so that's 3 strings of 5.

bb,
he was wondering not of the vmp being too high, but the voc being too high. each pv is 22.1voc so x 5 = 110.5voc total. the 20 degree f temp will add at the most <3v to it and is well below the controller max.

BB. · November 2010

Re: Solar Tracker, Kyocera 135w, U.S Battery Bank

Sorry, was heading out the door and messed up the post...

6 panels in series would be Voc-cold 149 volts at 14F
5 panels in series would be Vmp-hot 70 volts at 95F

-Bill

Solar Tracker, Kyocera 135w, U.S Battery Bank

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