140 watt Kyocera panels in a string of 4.

BilljustBill · November 2014

I'm getting my combiner boxes and disconnects purchased. Midnight has the MNPV6-Disco that has room for six of their breakers.

I'm reading that because the solar panels are classified as a continuous circuit, I have to multiply the rated amperage by 156% to allow for this. It appears it comes out to be 12.5 amps. Midnight has a 12 amp breaker and a 15 amp breaker.
If I use FOUR Kyocera 140w panels that produce 8 amps and 12v each, and each string is wired in series, what size breaker would I use for each string?

Also, this question about my FM80 Outback controller: My battery system is 24v with eight L-16, 6v, 440ah batteries. The max I can get through the FM80 with the 48v strings to a 24v battery bank is 2000 watts. I'll have room in the MNPV6-Disconnect for three 48 volt strings that would equal 1,680 watts plus a 48v string of 80 watt panels going to the same combiner box. Should I run the controller at 80% capacity, below it's rating and not push it, or could I add the extra 320 watts to MAX it's rating ability?

A majority of my system will be on a ground array. How I build it is based on the "Jacob's Coat" of solar panels I've gathered over the last 2-1/2 years....:-)

Thanks for your help,
Bill

Photowhit · November 2014

Re: 140 watt Kyocera panels in a string of 4.

BilljustBill wrote: »

I'm reading that because the solar panels are classified as a continuous circuit, I have to multiply the rated amperage by 156% to allow for this. It appears it comes out to be 12.5 amps. Midnight has a 12 amp breaker and a 15 amp breaker.

Check your specifications; Kyocera has a series fuse rating of 15 amps.

BilljustBill wrote: »

If I use FOUR Kyocera 140w panels that produce 8 amps and 12v each, and each string is wired in series, what size breaker would I use for each string?

While they each produce 8 amps at 12 volts, only the voltage adds when they are in strings, likely the reason they call it a series fuse rating. You will end up having a string of 48 volts nominal at 8 amps.

BilljustBill wrote: »

....I'll have room in the MNPV6-Disconnect for three 48 volt strings...

The box has 6 slots, unless your using it for other purposes, it will handle 6 strings, one breaker per string.

BilljustBill · November 2014

Re: 140 watt Kyocera panels in a string of 4.

Photowhit wrote: »

Check your specifications; Kyocera has a series fuse rating of 15 amps.
While they each produce 8 amps at 12 volts, only the voltage adds when they are in strings, likely the reason they call it a series fuse rating. You will end up having a string of 48 volts nominal at 8 amps.

The box has 6 slots, unless your using it for other purposes, it will handle 6 strings, one breaker per string.

Thanks for the 15amp "series fuse rating, information. I understand that the combiner box has six slots, but with my questions about the FM80 controller, I'm needing some input about how many watts I should have it operating at. Using 3 or 4 breaker slots of this combiner/disconnect, I'm already at the Outback's input watt rating.

Should I stop at 1,680 watts with three strings of 560 watts, or adding one more string of 320 watts, should I run the controller at its 2000 watt rating?

Thanks,
Bill

Photowhit · November 2014

Re: 140 watt Kyocera panels in a string of 4.

That is more to due with the use and battery bank, since you plan on having 8 - L-16's (I think the 440 amphour rate you post is a 100 hr rate) for a bank of 740-790 amphours at 24 volts, I'd say load it up, you have far too little an array for that size battery bank. The most you can cost effectively put on an 80 amp charge controller would be 80amps x 1.25(NOCT value) x 24 volts or about 240 watts of panels. You an limit the amperage out put or perhaps it's self limiting at 80 amps. This gives you just above the 10% charge rate on good days.

You need to keep your strings at the same voltage or you waste the lower voltage string. So at least 1 more string of 4 panels.

BilljustBill · November 2014

Re: 140 watt Kyocera panels in a string of 4.

Photowhit wrote: »

That is more to due with the use and battery bank, since you plan on having 8 - L-16's (I think the 440 amphour rate you post is a 100 hr rate) for a bank of 740-790 amphours at 24 volts, I'd say load it up, you have far too little an array for that size battery bank. The most you can cost effectively put on an 80 amp charge controller would be 80amps x 1.25(NOCT value) x 24 volts or about 240 watts of panels. You an limit the amperage out put or perhaps it's self limiting at 80 amps. This gives you just above the 10% charge rate on good days.

You need to keep your strings at the same voltage or you waste the lower voltage string. So at least 1 more string of 4 panels.

Thanks Photowhit. As Paul Harvey use to say, "And now,....the rest of the story...."

For the questions I'm asking, it's a focus on details of what will work the best. But, I see that the best way for asking questions and getting the best answers is first tell about the "whole", then go for the details. In designing the whole charging system, and the size and shape of the ground array, here is what I have aquired to use:

1. Eight 6v, 440ah, L-16 acid batteries. (I may add four more of these batteries as the final size of the bank)

1-a. The Amount of Wire and Wire Size is not an issue. It would surprise you, as it happily did me, how much copper wire is found at garage sales: Examples: 93' of 2/0 copper, 91' of 4/0 copper for $45 a roll, 90' of 4/0 copper for $100, 150' plus, of #6 copper "railroad" wire that is made to prevent/slow the forming of "black dust" for $5. A brand new 500' spool of #8 copper and half a the same size spool of #6 copper for $90 found at a flea market. And there are many more examples.

2. One group of 30 Kaneka 60w, 48v panels. 15 strings of two panels wired in Parallel equals 1800 watts. They are on their own FM80 controller.

3. One group of 12 Kyocera 140w panels wired in 3 strings of four panel equals 1680 watts. They are on their own FM80 controller.

4 One group of assorted new and used 12v, "Ebay/China" quality panels, in 4 strings of four panels each equals up to 2,000 watts. They will be on their own FM80

5. I have two GVFX3524 Outback inverters. I'm not sure if I'll run them as 220v or 120v.

5a. A Trimetric Battery Monitoring System, an Outback HUB, and MATE.

6. Enough 2x2" and 3x3" tubing to build the large ground array. I have the tracker parts and materials from a 12' diameter C-band dish. (I cut up the 12' aluminum dish and the scrap price of the aluminum paid for 3 Red Rock tracker modules.) I could have a shorter ground mount and with the twelve 140w Kyocera panels, one large tracker.

With all this in mind, how would you (and other members of this forum) run the FM80 controllers? At 80% of their ratings or at their full 2000 watt ratings? How would you wire the Outback inverters? With the current electric meter and disconnects needed, I can use the grid for all the 220v loads (deep water well, kitchen stove, clothes dryer, Central A/C, and shop welder) and wire the solar project to all other 110v circuits.

This system will not be tied to the grid due to past problems and issues with the Electric Co-Op I'm on.

Thanks again for your time and experience,
Bill

BilljustBill · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Photowhit wrote: »

That is more to due with the use and battery bank, since you plan on having 8 - L-16's (I think the 440 amphour rate you post is a 100 hr rate) for a bank of 740-790 amphours at 24 volts, I'd say load it up, you have far too little an array for that size battery bank. The most you can cost effectively put on an 80 amp charge controller would be 80amps x 1.25(NOCT value) x 24 volts or about 240 watts of panels. You an limit the amperage out put or perhaps it's self limiting at 80 amps. This gives you just above the 10% charge rate on good days.

You need to keep your strings at the same voltage or you waste the lower voltage string. So at least 1 more string of 4 panels.

PHOTOWHITT, I lost you on your formula, 240 watts?

Thanks,
Bill

Cariboocoot · December 2014

Re: 140 watt Kyocera panels in a string of 4.

He did the math wrong somehow.

80 Amp * 24 Volts / 0.77 derating = 1920 Watt array.

BilljustBill · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Thanks Caribootcoot, I've had it happen, too. Mind is going one direction and the keyboard fingers are going somewhere else....

How would you run a FM80 controller? At, say 80% of rating, or the full rating? The 10'x 50' ground array will begin 5' off the ground and extends 10' at a 33*degree angle. I'm planning to use the center sections, underneath the panel array to build two insulated rooms. One for the batteries and the other to hold the two 3524 inverters and the three FM80 controllers. Temps here in North Central Texas can go as high as 110 degrees in the summer, so there will have to be some "solar powered" cooling in July and August and can stay over 90 degrees past midnight. String runs of 48 volts will be at, or less, than 25 feet of #6 copper to the combiner boxes. Combiner boxes to the controllers will be 4 feet and 4 feet through the wall to the battery box. Battery box to inverters 4' or less of 4/0 copper

I haven't lived with inverters before, so I'm inexperienced with what to expect. With the large 2/0 and 4/0 wire remnants running 45 ft. from the array to the back wall of the house, almost no line loss is possible. If you've read what I have and will have when the full system is operational, what am I to expect having everything 50' from the house?

Thanks.

Cariboocoot · December 2014

Re: 140 watt Kyocera panels in a string of 4.

I have no qualms about running solar charge controllers at their peak because they won't run at their peak all day. The NEC definition of "continuous" is three hours, and if your system is maintaining full current for 3 hours ... it's a bit weird.

Let's review:
You've got 440 Amp hours of 24 Volt battery, yes?
So using the 10% rule-of-thumb you want at least (44 Amps * 24 Volts / 0.77) 1371 Watts of array.
Array Vmp has to be at least 35 for charging to work; go higher if necessary to make up for V-drop over long distances between array and controller. Beware of rising Voc under those circumstances.

Now if you are going to double that battery bank to 880 Amp hours at 24 Volts ... well, I wouldn't. I'd go up to 48 Volts instead. The reasons being that even a MidNite Classic would be maxed out trying to charger that much, and those L16's really want full 10% current. So there you are going to add a second controller ... but why, if you can save $600 by upping the system Voltage instead?

In either case the array would have to be doubled to at least 2742 Watts.

But it sounds like you are trying to use an assortment of panels which won't all have the same specs. Good luck. You need to get the string Vmp's very close on any one controller or else you will suffer power loss. You seem to be solving this by grouping the three like panel types together and spending an additional $1200 on charge controllers. Is this a good move economically? Let me guess; you've already bought all this equipment.

So 1800 Watts of Kanekas (I would have dumped those right off) about 58 Amps. 1680 Watts of Kyoceras about 54 Amps. 2000 Watts of "assorted others" about 64 Amps. None of those arrays are going to stress an FM80. Total current possibly 176 Amps. Why? That's enough for four times the 440 Amp hours of battery you have now. Or 20kW hours of stored power. Must be all that A/C you need down there.

As for line losses, they need to be calculated on a per circuit basis. It sounds like you intend to have a power house located at/near the arrays and run the AC from the inverters to the house across 50 feet. That may be the best way to go as the AC output can be at 120 or 240, either of which would be higher than any of the arrays would run. Keeping the equipment cool out there may well be another issue.

BilljustBill · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Cariboocoot wrote: »

I have no qualms about running solar charge controllers at their peak because they won't run at their peak all day. The NEC definition of "continuous" is three hours, and if your system is maintaining full current for 3 hours ... it's a bit weird.

Let's review:
You've got 440 Amp hours of 24 Volt battery, yes? Have 8 U.S. Battery L-16 batteries: 2 strings of 440= 880ah, plus one addition string totals 1320 ah?
So using the 10% rule-of-thumb you want at least (44 Amps * 24 Volts / 0.77) 1371 Watts of array.
Array Vmp has to be at least 35 for charging to work; go higher if necessary to make up for V-drop over long distances between array and controller. Beware of rising Voc under those circumstances.

Now if you are going to double that battery bank to 880 Amp hours at 24 Volts ... well, I wouldn't. I'd go up to 48 Volts instead. Can't go up because of the 30 Kaneka 60w panels are 48volt. Too low for 48v system charging. Two Kaneka in series risks over-voltage on cloudy days or cold days.
The reasons being that even a MidNite Classic would be maxed out trying to charger that much, and those L16's really want full 10% current. So there you are going to add a second controller ... but why, if you can save $600 by upping the system Voltage instead?

In either case the array would have to be doubled to at least 2742 Watts.

But it sounds like you are trying to use an assortment of panels which won't all have the same specs. Good luck. You need to get the string Vmp's very close on any one controller or else you will suffer power loss. You seem to be solving this by grouping the three like panel types together and spending an additional $1200 on charge controllers. Is this a good move economically? Let me guess; you've already bought all this equipment. Yes, I have the equipment, paid for as I went. But, paid for with 'somebody else's money' from my own garage sale profits and two years ago the sale of gold and silver I found in jewelry at other people's garage sales. After setting a goal of a PV system, and trying to "be prepared" for the dismal economic forecast of our economy, if things went South, as time and profits allowed, I had enough PV for lights, a small 6000btu window A/C unit, and minimum refrigerator/freezer operation. Didn't count on the drop of solar panel prices! But such are the perils of doing it this way. The silver lining of all this is having, with the help of this forum and one special forum member, a PV system that when it is operational, it's full cost paid for, and then getting the IRS Tax Credit that will give me $3,000 profit for my work.

So 1800 Watts of Kanekas (I would have dumped those right off) about 58 Amps. For good or bad, two years ago, they cost $39.95 each; delivered to my driveway. It did cost $570 for a dedicated FM80 controller. From some that own them, I understand that these panels produce power in a wider range of conditions. We'll see, since I'll be able to compare FM80's with the Kyocera panels on their own FM80 and under the same sunlight conditions..
1680 Watts of Kyoceras about 54 Amps. 2000 Watts of "assorted others" about 64 Amps. None of those arrays are going to stress an FM80. Total current possibly 176 Amps. Why? That's enough for four times the 440 Amp hours of battery you have now. Or 20kW hours of stored power. Must be all that A/C you need down there.

As for line losses, they need to be calculated on a per circuit basis. It sounds like you intend to have a power house located at/near the arrays and run the AC from the inverters to the house across 50 feet. That may be the best way to go as the AC output can be at 120 or 240, either of which would be higher than any of the arrays would run. Keeping the equipment cool out there may well be another issue.

Thanks for your help, Carb. I've added additional info in your original post above.

Bill

Photowhit · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Cariboocoot wrote: »

He did the math wrong somehow.

80 Amp * 24 Volts / 0.77 derating = 1920 Watt array.

100 / .77 = @130

SO I should have multiplied by 1.3 rather than 1.25...

a /.77= a x 130

Multiplying and dividing are 2 sides of the same coin...

Photowhit · December 2014

Re: 140 watt Kyocera panels in a string of 4.

BilljustBill wrote: »

My battery system is 24v with eight L-16, 6v, 440ah batteries.

Since you have a "880 ah" battery bank, I think if you check you are stating a 100 hr rate for the battery rather than a 20 hr rate which we commonly use in calculations. I think the 20 hr rate would be perhaps 390 ah. So lets assume a 780 ah battery.

I think you may run the risk of having too high a charge rate with the combined arrays. Normally I could see going to about 15% of the capacity(at 20 hr rate) or 117 amps into the battery. So 117 amp x 24 volts = 2808 watts of array x 1.3 (for the NOCT value) = @ 3650 call it 3700 watt array (for the charge controller inefficiency) would be the normal max array. You might never reach this potential, and indeed the max current would be at 24 volts would be unusual, since this would indicate a battery drawn down to a near 20% SOC, but the possibility remains.

Figured at the max bulk and early absorption figure 117 amps at @29 volts(Trojan batteries) = 3393watts x 1.3(NOCT value) = 4410 watt array max cost effective. You may want to limit the amperage going into the batteries if you want to exceed this size array, unfortunately I don't know if you can do this with any system yet other than limiting your individual charge controllers.

Photowhit · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Cariboocoot wrote: »

He did the math wrong somehow.

80 Amp * 24 Volts / 0.77 derating = 1920 Watt array.

Yeah some how I clipped out something, I can't recall, but the above total should be 2493 or there abouts'

80 x 24 x 1.3 = 2496 watts

So somewhere in that area, I did a bit more through run above with the 'rest of the story' info calculating max array total.

Sorry Now I see the math problem, recall trying to subtract the existing array to come up with the needed additional wattage, then striking it all. obviously cut the wrong stuff.

Cariboocoot · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Photowhit wrote: »

100 / .77 = @130

SO I should have multiplied by 1.3 rather than 1.25...

a /.77= a x 130

Multiplying and dividing are 2 sides of the same coin...

Yes, they are. But sometimes the way a formula is written helps to understand the purpose of the numbers, as in panels + controller being 77% efficient (instead of writing the reciprocal) on average.

In retrospect I thought maybe you'd used a shortcut of 80 Amps * 30 Volts charging to get 2400 Watts, and then left off a zero.

When it comes right down to it, you can load up a good MPPT controller even higher than that because it will just clip the extra current it can't handle. It gives a small margin of extra power for less-than-sunny days, but there's no practical point in going overboard if the PV is going to do nothing most of the time.

Usually 20% above the max @ Absorb Voltage starts to be economically unfeasible. That's roughly 28.8 * 80 Amps * 1.20 or 2765 Watts.

Photowhit · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Cariboocoot wrote: »

When it comes right down to it, you can load up a good MPPT controller even higher than that because it will just clip the extra current it can't handle.

My point on having a "risk of having too high a charge rate with the combined arrays" is from his 'rest of the story' post stating he will have 3 - 80 amp charge controller hooked up to this battery bank!

Since this is the current state is nicely over paneled. If we go back to his original question on adding a 4th string to the 3rd controller, I really don't see a reason to unless your just running that controller while running additional loads during the day...

Cariboocoot · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Photowhit wrote: »

My point on having a "risk of having too high a charge rate with the combined arrays" is from his 'rest of the story' post stating he will have 3 - 80 amp charge controller hooked up to this battery bank!

Since this is the current state is nicely over paneled. If we go back to his original question on adding a 4th string to the 3rd controller, I really don't see a reason to unless your just running that controller while running additional loads during the day...

Yes indeed.
On the one hand we're talking in the abstract: what can a single controller handle?
But on the other we've got the specific: there are three separate arrays feeding three separate controllers to one battery bank.
In the latter case none of the 80 Amp controllers is in danger of being overloaded, according to the amount of panel specified on each one at this point. But the combined current is quite high and may prove too much for a battery bank, depending on what size and type that ends up being.

On the whole it's another lesson in why accumulating things over time and then trying to get them to all work together isn't such a good plan.

BilljustBill · December 2014

Re: 140 watt Kyocera panels in a string of 4.

:roll:

Cariboocoot wrote: »

Yes indeed.
On the one hand we're talking in the abstract: what can a single controller handle?
But on the other we've got the specific: there are three separate arrays feeding three separate controllers to one battery bank.
In the latter case none of the 80 Amp controllers is in danger of being overloaded, according to the amount of panel specified on each one at this point. But the combined current is quite high and may prove too much for a battery bank, depending on what size and type that ends up being.

On the whole it's another lesson in why accumulating things over time and then trying to get them to all work together isn't such a good plan.

Carib,

Thanks for you help. It's been, and more to come, of a learning curve in solar power. There are at least three bright spots in all this accumulation of materials and knowledge. 1. Since the system is on a ground array, I'll have to carry separate rider for my homeowner's policy. But should the dreaded "Hail/Wind Storm" hit, the actual investment cost compared to replacing them with what is being used at that point due to a catastrophic storm damage event should be a gainful experience. Then, I can start over with a "textbook system" for little, if any monetary loss. #2. In using three FM80 controllers and two 3524 inverters, there is almost three times the redundancy factor as the others can keep going if I were to LOSE one of the two inverters or two of the three controllers. #3. Don't be too pessimistic about my process. It's not like Johnny Cash's song:

https://www.youtube.com/watch?v=0ynSm1Ngfn8

As I see it, raising a solar project over time while paying with "somebody else's money" and accumulating parts and materials , is like raising a growing family with an accumulation of kids. Over time, it appears they both are about the same. The kids usually turn out okay, don't they? There's just a few more gray hairs in my head.

Thanks again for your help,
Bill

BilljustBill · December 2014

Re: 140 watt Kyocera panels in a string of 4.

Home system- 20 - 200W Evergreen blems, 2 Classic Lites, E-Panel, 2 Prosine 1800 watt inverters, 800AH 24V forklift Batt, up and running 1 Classic Lite and 14 Suntech 185W in spare room.
Experience with Pulse/Trace PC250 Power Center, Original Rouge CC, 80-4/5watt 6v panels, Odds and extras,

Photowhit,

I see in your byline that you use a a 24v forklift battery. How has that worked for you? More/Less in maintenance? Size/Weight, issues in getting it placed where you want it? Expected longevity compared to common or "solar" versions of L-16 size batteries?

Thanks,
Bill

Photowhit · December 2014

Re: 140 watt Kyocera panels in a string of 4.

BilljustBill wrote: »

Home system- 20 - 200W Evergreen blems, 2 Classic Lites, E-Panel, 2 Prosine 1800 watt inverters, 800AH 24V forklift Batt, up and running 1 Classic Lite and 14 Suntech 185W in spare room.
Experience with Pulse/Trace PC250 Power Center, Original Rouge CC, 80-4/5watt 6v panels, Odds and extras,

Photowhit,

I see in your byline that you use a a 24v forklift battery. How has that worked for you? More/Less in maintenance? Size/Weight, issues in getting it placed where you want it? Expected longevity compared to common or "solar" versions of L-16 size batteries?

So far so good, Sorry I didn't see this post earlier. I've had it 4 years now (I think) I actually had to move it, change in rules prohibited me from continuing to live at my cabin, and moved to my new place. it was a bit of a pain, but did it my self with large levers.

I t appears to be chugging along well, does require a bit more maintenance, more watering has changed to about the same after adding water miser battery caps, Equalizing monthly as maintenance. I don't know what to expect, NAWS says 20 years is a common life expectancy for the Crown line they sell, I've used 15 years as an expected life, time will tell...

140 watt Kyocera panels in a string of 4.

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