Brainstorming they say...

[Weldman]

I got an slew of information to brainstorm over. Bought (24) Trina 395W Bi-Facial panels that need to go about 750 feet to charge controller and the system is 48V. So question is how would you set it up series or parallel and what would you use for charge controllers to harness such power? Currently have Midnite Classic 150 SL to add to the mix which can be tossed for other uses if need be.
Here is the numbers of the panels to add to the equation.

 

[Steve_S]

Running 48VDC over 750' ? Ohhh you are gonna have issues with that idea, DC and Long Runs is not fun and problematic "at best".
May be more prudent to build an individual Power House close to the panels and run AC from there to your target buildings. AC can travel distance easily, the saving on wire alone would likely cover the cost of building the little powerhouse.

That amount of panels will require multiple SCC's daisy chained together. The Classic 150SL can chain (using Follow-Me) to other Midnite Classics. The availability of the SL is not known anymore.

 

[Ampster]

At a conceptual level wire loss is the issue over distance. Increasing wire size is one solution to compare with increasing voltage of the charge controller input voltage. The one variable you cannot change is battery voltage. Also, Aluminum is less expensive than copper but it takes larger aluminum wires to get same wire loss.
As @Steve_S points out, you may want to also consider the cost of Powerhouse in that analysis.

 

[snoobler]

750 feet is a nightmare.

Toss the Classic now.

Parallel should be done only when necessary.

You need to familiarize yourself with this tool:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

24 * 395W = 9480W of power

9480W/48V= 198A of charge current

Voc 49.7V (rounding to 50).
Vmp 40.6V
Isc 10.29
Imp 9.73

Schnieder makes a spendy 80A, 600V SCC.

600V/50V = 12 panels in series. You need to leave some cold temperature margins, so you would fall back to 8 panels in series with 3 in parallel

For the voltage drop calculator, you look at Vmp and Isc as worst cases:

8S3P array produces 397.6V and 30.87A

Running 3 sets of 8awg from the array to THREE separate 80A/600V Schnieder controllers (about $1200 each), will produce a 2.44% voltage drop - pretty good.

If you could get away with 22 panels...

11S2P. You could probably get away with 2X SCC only losing a little of the array's performance at peak output.

547V, 20.58A - 1.77% voltage drop, and you're only running 2 sets of 8awg conductors rather than 3 and saving $1200 on a 3rd charge controller and $XX on two less panels.

Of course if you need the extra 800W, it won't work.

This is a dance of wire cost vs. equipment cost.

You could make it work with your Classic, but you'd have to run two pairs of 4/0 conductors 750 feet... That might be a bit expensive.

 

[Weldman]

Actually I see some people are here from Midnites website and I see some from Solar Panel Talk here too, looks like I found the place where all congregate.
Anywho I am not running the 48VDC that far I am running the voltage of said panels that far and see Schneider has a 100A 600VOC unit which as Snoobler pointed out I could run 11S2P with it. Won't keep it at 750' ft forever only reason going this far of distance is where the RV rig is we live in till house gets built and there is no way I can put the rig closer with landscape here. When house is built it will be about 350' distance.
Thought about tossing the Classic and keeping it for RV rig when it hits the road so now I see it's confirmed to toss it from the mix then I will do so.
Also seen they have 2kV aluminum solar wire is what I am going to use. I just wanted to make sure I had my numbers right and by the responses I did. Reason I bought 24 panels was so 2 can be spare/power odd things, I was just seeing if it was possible to add them in the 11S2P thing but as everyone pointed out it won't work unless I bought 9 more panels and had 3 Schneiders.
Here is the calculations I came out to after tinkering around...

 

[MisterSandals]

Won't keep it at 750' ft forever only reason going this far of distance is where the RV rig is we live in till house gets built and there is no way I can put the rig closer with landscape here. When house is built it will be about 350' distance.

It sounds like your goal is to build your ground based array once. This is a good goal but with the wiring challenges, have you considered roughing out an array temporarily closer to your RV until your house is built?

 

[Weldman]

It sounds like your goal is to build your ground based array once. This is a good goal but with the wiring challenges, have you considered roughing out an array temporarily closer to your RV until your house is built?

Yes I have but to have that many panels in a temp set up is asking for trouble here, i.e. right now winds are gusting to 65 mph and to have few instead of all panels is not enough for the stuff I do. I am trying to get enough power for running power tools and welding without running genset. Max amperage my welding machine pulls is 30A but that’s part of the problem, wife likes to run power tools too while I’m running power tools while powering up a RV rig.

 

[Weldman]

This what I see in what is needed in wire size or smaller, and how much it will cost for 4 wires at said length. Does this look right?

 

[snoobler]

Actually I see some people are here from Midnites website and I see some from Solar Panel Talk here too, looks like I found the place where all congregate.
Anywho I am not running the 48VDC that far I am running the voltage of said panels that far and see Schneider has a 100A 600VOC unit which as Snoobler pointed out I could run 11S2P with it. Won't keep it at 750' ft forever only reason going this far of distance is where the RV rig is we live in till house gets built and there is no way I can put the rig closer with landscape here. When house is built it will be about 350' distance.
Thought about tossing the Classic and keeping it for RV rig when it hits the road so now I see it's confirmed to toss it from the mix then I will do so.
Also seen they have 2kV aluminum solar wire is what I am going to use. I just wanted to make sure I had my numbers right and by the responses I did. Reason I bought 24 panels was so 2 can be spare/power odd things, I was just seeing if it was possible to add them in the 11S2P thing but as everyone pointed out it won't work unless I bought 9 more panels and had 3 Schneiders.
Here is the calculations I came out to after tinkering around...View attachment 42981

Not sure what you're looking for. The MidNite won't work for this application.

11S2P would work with 2X of the Schnieders - didn't realize they were 100A - that means you're good to go on capturing the whole array.

2 pairs of 8awg (COPPER) from panels to SCC will have < 2% drop. Win.

 

[snoobler]

This what I see in what is needed in wire size or smaller, and how much it will cost for 4 wires at said length. Does this look right?View attachment 42997View attachment 43000

Anything less than 2-3% over 750ft is something to be proud of. I wouldn't shoot for < 1%.

You will need to run FOUR wires from the array - a pair of wires for each MPPT. Technically, you have two separate 11S arrays.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Per the above, 6awg aluminum (4 total wires for 750 feet) is a 1.88% voltage drop.

 

[Weldman]

Not sure what you're looking for. The MidNite won't work for this application.

11S2P would work with 2X of the Schnieders - didn't realize they were 100A - that means you're good to go on capturing the whole array.

2 pairs of 8awg (COPPER) from panels to SCC will have < 2% drop. Win.

Was looking to make sure my math was right before switching the flip and lighting up the whole hillside like Independence day celebration and if there might of been anything I missed in variables on ways I could make this more effective.

 

[Weldman]

Anything less than 2-3% over 750ft is something to be proud of. I wouldn't shoot for < 1%.

You will need to run FOUR wires from the array - a pair of wires for each MPPT. Technically, you have two separate 11S arrays.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Per the above, 6awg aluminum (4 total wires for 750 feet) is a 1.88% voltage drop.

It’s what I said I would need 4 wires and all of equal size per NEC.

 

[snoobler]

The MidNite calculator and my numbers mesh. I'm certainly confident of the data I'm providing.

 

[Weldman]

The MidNite calculator and my numbers mesh. I'm certainly confident of the data I'm providing.

Yep they do and I appreciate you running them through for me, not doubting you at all.

 

[snoobler]

Yep they do and I appreciate you running them through for me, not doubting you at all.

Free advice is worth what you pay for it...

 

[Roswell Bob]

You seem to have quite a bit of panels. Do you live in the sun belt? In any case my guess is that you have way more juice than you need. Welders or not. What are you are willing to give up in line losses? In better terms, how much power do you need I expect you would do fine in a RV with half the power those panels are putting out.

I am off grid and totally pleased with a pair of 2kW solar arrays. I run welders off of those panels too.

 

[Weldman]

You seem to have quite a bit of panels. Do you live in the sun belt? In any case my guess is that you have way more juice than you need. Welders or not. What are you are willing to give up in line losses? In better terms, how much power do you need I expect you would do fine in a RV with half the power those panels are putting out.

I am off grid and totally pleased with a pair of 2kW solar arrays. I run welders off of those panels too.

What thickness are you welding? I can pull up to 50 amps on my welder and it has inverter technology which I mostly pull around 30 amps AC which according to my calculations 6600 watts and up. Not wanting to turn all the lights out and appliances in the house or RV to weld.
No I don't live in the sun belt I live in Big Sky Country as they call it here in Montana.
This is not just for my RV it's for my future home here, I already have a system that's for the RV but just like pulling a plug out of a wall outlet the DC and AC do the same on the RV, it's how I designed it.
Look close in first picture you can see one of two portable racks I welded for panels, and that's us on the Grand Canyon, who needs an RV park when you have enough power and water for weeks at a time...
All was done with marine grade hardware including wiring from Ancor based on ABYC and NEC's.

 

[Weldman]

WAIT!!! I had an epiphany... besides the 11S2P I can take one of the 2 spare solar panels and put in a DC fence charger (electric fence). Won't need many batteries as there will be a timer it runs on it. Had horses break my fence that I use to keep horses out (ironic) with and destroyed some of my property.

 

[snoobler]

My neighbor has a 2 mile long electric fence (around my parcel as well), and 200W is more than enough to keep the 12V charged, so you should be able to turn the zapper up to 11!

 

[Weldman]

My neighbor has a 2 mile long electric fence (around my parcel as well), and 200W is more than enough to keep the 12V charged, so you should be able to turn the zapper up to 11!

At this rate sounds like I can also power up a gate opener too! Will feel bad if I went that luxurious out here, one neighbor 3 miles out burns her house to ground every few years other ones live in campers/RV's on gensets (me and wife placing bets before they burn out) and another has dirt floor shack built from scraps.

 

[snoobler]

At this rate sounds like I can also power up a gate opener too! Will feel bad if I went that luxurious out here, one neighbor 3 miles out burns her house to ground every few years other ones live in campers/RV's on gensets (me and wife placing bets before they burn out) and another has dirt floor shack built from scraps.

You'll likely be able to repeatedly open the gate like a kid rapid-flipping a light switch from sunrise to sunset and end the day at 100% SoC.

 

[Roswell Bob]

If you have 24x395W of panel then you have nearly 10kW of power. Assume 4 hours of sun then we got 40kWh of energy. Are you using 40kWh each day. My guess is no unless you are growing a lot of weed indoors or producing anvils. Can you live with 20kWh of energy each day? That is quite a bit of energy. If the answer is yes then you can sustain 50% losses in the wiring. Best way to do it as already been discussed is to go with the higher voltage. Putting the inverter at the panels in my mind is not the way to go. You still have 750' to deal with and you can't afford voltage drops on the AC side. Inverters do not have remote sensing capability to compensate for drops in the line. 10-4 cord if you can get it for $1.20 a foot would put you close to a grand for wire. #10 wire is 0.001ohm/ft, so we're talking 1.5 ohm round trip. Lets assume a configuration of 3S4P configuration for each pair of wires. . That would keep the max DC voltage near 120v with say 40amps. At 40A you will loose about 60v so efficiency is close to 50%. That is without going broke. You can try other combinations that you may like better. As others have already said your best bet would probably be a 12S2P configuration, but then you are messing with considerably higher DC voltages which tend to get dangerous.

You may want to relocate that Aims inverter away from battery. The battery gassing will eat up the pc boards in a hurry.

Looks like you have a nice setup out there. I've been cross-country a few times and make a point to go through Big-Sky country. Woke up in Butte one morning in the back of a station wagon. It was 30 below.

Good luck

 

[Roswell Bob]

Most I weld is 1/2". I have inverter welder too.

One other thought - since you weld. I put together a pole mount system for cost. I used 8" schedule 40 for upright. Bought the 22' pipe and had it cut in half for two mounts. Welded pipe flange on top and sunk em into a yard of concrete. Welded a 6' piece of junior beam to another flange for the cross. Mounted a trailer axle across the top beam and hung panels on axle. In the winter they go up to near verticle and never a problem with snow. Sun comes up and whtever little snow has collected is gone. Many up here in NH do roof mount and have terrific problem in the winter with snow. I would guess same probs in Big Sky country. Pics are on my FB page. Roswell Bob LaFrank.

 

[Weldman]

If you have 24x395W of panel then you have nearly 10kW of power. Assume 4 hours of sun then we got 40kWh of energy. Are you using 40kWh each day. My guess is no unless you are growing a lot of weed indoors or producing anvils. Can you live with 20kWh of energy each day? That is quite a bit of energy. If the answer is yes then you can sustain 50% losses in the wiring. Best way to do it as already been discussed is to go with the higher voltage. Putting the inverter at the panels in my mind is not the way to go. You still have 750' to deal with and you can't afford voltage drops on the AC side. Inverters do not have remote sensing capability to compensate for drops in the line. 10-4 cord if you can get it for $1.20 a foot would put you close to a grand for wire. #10 wire is 0.001ohm/ft, so we're talking 1.5 ohm round trip. Lets assume a configuration of 3S4P configuration for each pair of wires. . That would keep the max DC voltage near 120v with say 40amps. At 40A you will loose about 60v so efficiency is close to 50%. That is without going broke. You can try other combinations that you may like better. As others have already said your best bet would probably be a 12S2P configuration, but then you are messing with considerably higher DC voltages which tend to get dangerous.

You may want to relocate that Aims inverter away from battery. The battery gassing will eat up the pc boards in a hurry.

Looks like you have a nice setup out there. I've been cross-country a few times and make a point to go through Big-Sky country. Woke up in Butte one morning in the back of a station wagon. It was 30 below.

Good luck

Thanks on the compliments and I have had that Aims inverter/charger down there the past 2 or 3 years now with plenty of ventilation with no problems and is of a temp set up. I bought the rig for $750 was a beverage truck I cut in half and welded a pedestal for the camper on bottom half then fabricated 4 doors to access the bottom which was broken up to 3 open compartments on each side, water on one side solar on other right next to rear axle for traction. Next rig as I have snapped the axle on this one will have more room for solar on board to keep such things separated. Could of would of should of bought a new 3rd member for this rig but it's time to get a rig with air brakes (I already have CDL w/air brakes endorsement) and stop wondering if I am going to lose the brakes on Homestead Pass.

If we go off maximum numbers it's technically 24x494W of panel at it's maximum wattage due to them being half cut bi-facial panels at 11,856 watts and it's for what I will get on the worse days reason I got so many. I'm not the only one that welds here either the wife likes to weld with her welding machine and run the power tools too. We have came to consensus that 11S2P is what we are going to run here and the other two will be just for spares i.e. electric fence to keep horses/cows out.
Speaking of welding solar array mount I plan on 4" drill pipe every 20 feet in the ground and just going in straight line with them at about 80 feet long that way don't have to worry about shading the back side of them and it's easier. The ground isn't leveled here at all so trying to put one set of panels behind other would required excavation and leveling out.

We got it down to 32 below zero with 50 below gusting wind this winter out here, wasn't bad only part sucked was trying to start any engines of anything. Stayed nice and toasty in here with diesel heater I installed plus 2 inches of closed cell spray insulation with 1 inch of loose cellulose insulation to break any thermal bridging and layer of sound dampening vinyl.
I don't mess with social media websites like FB or whatever might be out there so I can't see pictures.

I'm curious, did you mean to wake up in Butte or were you supposed to wake up in another city and did it involve alcohol?

 

[Weldman]

I looked it up and it averages 5 hrs a day here so after mathematics that's 50 kWh a day anywho here is the panels we offloaded here...

Alright hun that's one, twenty-three more to go...