Off Grid System Verification - Please Help!
SteveG
Registered Users Posts: 19 ✭
Hi everyone. I've been here a while getting information and trying to figure out a solar system. If you could please verify whether or not the following system will work (and work efficiently in this setup) that would be great. Thank you.
Array:
( 18 ) Lumos Modules LSX180-72M - Pmpp 180W, Voc 44.8V, Isc 5.29A, Vmpp 36V, Impp 5A . There will be 9 strings of 2 each.
( 8 ) Yingli Solar Panels YL235P-29b - Pmpp 235W, Voc 37.0V, Isc 8.54A, Vmpp 29.5V, Impp 7.97A. There will be 4 strings of 2 each.
Combiners/Fuses:
The Lumos panels will go to one combiner, each breaker containing a 10A fuse (their series fuse rating). The Yingli panels will go to their own combiner, each with a 15A fuse. The combiners used will be Midnite Solar MNPV12 Combiner boxes, with the fuse holders and fuses to match.
Charge Controllers:
I will be using (2) charge Tristar 60 charge controllers. I used the Morningstar string calculator to find the array setup above. In Michigan, I estimate 4.2 noon sun hours and a minimum temperature of -10 degrees F and a max temp of 100 degrees F. Should MPPT-60 controllers be used in this system instead?
DC Disconnect: 60A 600VDC Square D disconnect.
Batteries:
Since we will have approximately 5120W of solar array, using the equation for 10% charge rate, I estimated a 48V, 745 Ah system would be about right. Thus I propose (2) Crown 745 Ah 24V forklift batteries wired in series.
5120W = .10 (10% charge) * 1/0.77 (derating) * 59V (charge voltage) * ???? (Amp hours) -> approx 668 Ah. Maybe the 635 batteries are a better option?
5120W = .08 (8% charge) * 1/0.77 (derating) * 59V (charge voltage) * ???? (Amp hours) -> 835 Ah. Maybe either battery bank would work.
Battery Monitor:
We will be using a Pentametric Battery Monitor system for these batteries. This includes the display and the computer interface.
Inverter:
Since we will mainly be running lights on the system (although there are many of them) I figured that the Outback 3048T would be sufficient to suit our needs. This inverter will supply power to a breaker box, which will in turn be wired up to the grid in case of lack of sun (cloudy days for a week). An AC disconnect will be between the breaker box and the grid, so we can switch between the power sources as needed. An electrician will be doing all the wiring.
Grounding Rod:
We will be using a 10' grounding rod for the system, which may or may not be overkill.
A diesel generator (2000W) will charge the batteries if needed during a blackout if we put different loads on the inverter (fridge, networking stuff, etc). Also, I know that off-grid systems are not the most cost effective systems (at $1-2 a kW of energy), but we have the panels and mounting systems lying around that we'll be testing, so we figured we may as well get energy from them while they're sitting around. Also, the loads we will place on the batteries will only be enough to bring the batteries close to 50% DOD at maximum. We may not discharge the batteries this much, but it's just the maximum.
What do you think about the setup of this system? Will the strings of panels be compatible with the other components, or should they be wired differently. Also, what gauge of wire should be used for this system in between components? (Ground as well)
Also, for wiring, the panels will wire into the combiners, then to the charge controllers, then both wires will meet at the first battery in series.
Array:
( 18 ) Lumos Modules LSX180-72M - Pmpp 180W, Voc 44.8V, Isc 5.29A, Vmpp 36V, Impp 5A . There will be 9 strings of 2 each.
( 8 ) Yingli Solar Panels YL235P-29b - Pmpp 235W, Voc 37.0V, Isc 8.54A, Vmpp 29.5V, Impp 7.97A. There will be 4 strings of 2 each.
Combiners/Fuses:
The Lumos panels will go to one combiner, each breaker containing a 10A fuse (their series fuse rating). The Yingli panels will go to their own combiner, each with a 15A fuse. The combiners used will be Midnite Solar MNPV12 Combiner boxes, with the fuse holders and fuses to match.
Charge Controllers:
I will be using (2) charge Tristar 60 charge controllers. I used the Morningstar string calculator to find the array setup above. In Michigan, I estimate 4.2 noon sun hours and a minimum temperature of -10 degrees F and a max temp of 100 degrees F. Should MPPT-60 controllers be used in this system instead?
DC Disconnect: 60A 600VDC Square D disconnect.
Batteries:
Since we will have approximately 5120W of solar array, using the equation for 10% charge rate, I estimated a 48V, 745 Ah system would be about right. Thus I propose (2) Crown 745 Ah 24V forklift batteries wired in series.
5120W = .10 (10% charge) * 1/0.77 (derating) * 59V (charge voltage) * ???? (Amp hours) -> approx 668 Ah. Maybe the 635 batteries are a better option?
5120W = .08 (8% charge) * 1/0.77 (derating) * 59V (charge voltage) * ???? (Amp hours) -> 835 Ah. Maybe either battery bank would work.
Battery Monitor:
We will be using a Pentametric Battery Monitor system for these batteries. This includes the display and the computer interface.
Inverter:
Since we will mainly be running lights on the system (although there are many of them) I figured that the Outback 3048T would be sufficient to suit our needs. This inverter will supply power to a breaker box, which will in turn be wired up to the grid in case of lack of sun (cloudy days for a week). An AC disconnect will be between the breaker box and the grid, so we can switch between the power sources as needed. An electrician will be doing all the wiring.
Grounding Rod:
We will be using a 10' grounding rod for the system, which may or may not be overkill.
A diesel generator (2000W) will charge the batteries if needed during a blackout if we put different loads on the inverter (fridge, networking stuff, etc). Also, I know that off-grid systems are not the most cost effective systems (at $1-2 a kW of energy), but we have the panels and mounting systems lying around that we'll be testing, so we figured we may as well get energy from them while they're sitting around. Also, the loads we will place on the batteries will only be enough to bring the batteries close to 50% DOD at maximum. We may not discharge the batteries this much, but it's just the maximum.
What do you think about the setup of this system? Will the strings of panels be compatible with the other components, or should they be wired differently. Also, what gauge of wire should be used for this system in between components? (Ground as well)
Also, for wiring, the panels will wire into the combiners, then to the charge controllers, then both wires will meet at the first battery in series.
Comments
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Re: Off Grid System Verification - Please Help!
Welcome to the forum.
I hope you haven't spent any money yet, because you're missing the most important numbers of all: how much power do you need?
Really you're designing your system back-to-front. You say "we will mainly be running lights". That can be anywhere from a couple of LED bulbs briefly at night on up. Without numbers for total (at one time) Watts and daily Watt hours you are in essence picking equipment at random and hoping it will do the job. This is called "Ready, Fire, Aim!" around here.
Here's another intriguing phrase from your post: "a breaker box, which will in turn be wired up to the grid". That begs the question; if you've got grid why are you investing in solar? Particularly off-grid solar. It really doesn't make economic sense, but perhaps you have another reason? Your components as stated add up to a really big off-grid system. That's a lot of money to invest, and it may be more than you need to spend to accomplish your goal - once we know what that goal is.
A 600+ Amp hour 48 Volt battery bank is like 15kW hours of power. That's roughly what my in-town house uses, with an electric hot water heater.
I'm going to suggest you rethink the whole thing, starting with why you're doing it and how much power you really need. Frankly spending $30 on a Kill-A-Watt meter is the best investment you can make, followed by replacing everything that turns out to be an energy hog. This is true even if you don't go with any type of solar power and especially true if you do. If the grid is available, then GT solar is a far more sensible investment than off-grid. -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »Welcome to the forum.
I hope you haven't spent any money yet, because you're missing the most important numbers of all: how much power do you need?
Really you're designing your system back-to-front. You say "we will mainly be running lights". That can be anywhere from a couple of LED bulbs briefly at night on up. Without numbers for total (at one time) Watts and daily Watt hours you are in essence picking equipment at random and hoping it will do the job. This is called "Ready, Fire, Aim!" around here.
Here's another intriguing phrase from your post: "a breaker box, which will in turn be wired up to the grid". That begs the question; if you've got grid why are you investing in solar? Particularly off-grid solar. It really doesn't make economic sense, but perhaps you have another reason? Your components as stated add up to a really big off-grid system. That's a lot of money to invest, and it may be more than you need to spend to accomplish your goal - once we know what that goal is.
A 600+ Amp hour 48 Volt battery bank is like 15kW hours of power. That's roughly what my in-town house uses, with an electric hot water heater.
I'm going to suggest you rethink the whole thing, starting with why you're doing it and how much power you really need. Frankly spending $30 on a Kill-A-Watt meter is the best investment you can make, followed by replacing everything that turns out to be an energy hog. This is true even if you don't go with any type of solar power and especially true if you do. If the grid is available, then GT solar is a far more sensible investment than off-grid.
Thank you, Cariboocoot!
As I stated above, we already have the panels and mounting. The system is for a company that tests solar panels and mounting, so we already have the panels lying around. We simply want to run as much electricity from these batteries as possible. Since our electric bill is 4800 kWh a month (due to A/C, 15 computers, tons of light, etc), we want to ease the pressure from the bill as much as possible.
So as for loads, the battery bank specified above should give us approx 17.5 kWh, which isn't nearly enough to offset our electric bill. (4800/30 = 160 kWh per DAY)
And since we don't own the building, we can't do grid-tied. Although we want to, believe me. We figured that this could be a system that we could later move to another location if needed. Besides, the owner won't let us put holes or ballasted mounting systems on the roof.
I definitely understand your concern as to the Ready, Fire, Aim! mentality. So rest assured, we haven't bought anything yet.
So based on the system above, the questions still remain
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Re: Off Grid System Verification - Please Help!
So basically you're setting up a system to test panels? That's going to be a bit awkward because not all panels will have the same Voltage/current and so the configuration would differ.
As far as the panels listed are concerned, you would need to run two 36 Vmp in series to have enough Voltage to charge a 48 system, so you're okay with that part. Eighteen 180 Watt panels would be 3240 Watts and might be expected to supply: 3240 * 0.77 / 48 = 52 Amps. One 60 Amp controller should handle that.
The Yingli's Vmp is only 29.5: two in series will not provide enough Voltage for charging a 48 Volt system. That's only 59 Volts, and what with one thing and another there may not be enough to reach full charge (panels heat up = Voltage goes down, wire consumes some). You can't run four in series either, as the Voc would exceed the TriStar's input limit. Any chance of getting one more and having three strings of three? Otherwise the eight 235 Watts would be 1880 Watts and supply about: 1880 * 0.77 / 48 = 30 amps peak charge current. Together with the others this would be over 80 amps current, enough for 800 Amp hours of battery (around 19 kW hours max). You must use an MPPT controller with these panels due to their odd Vmp, and the others would definitely benefit from one as well.
Potential AC Watt hours from the first array: 3240 * 4 * 0.52 = 6.7 kW hours. From the second: 1880 * 4 * 0.52 = 3.9 kW hours. A bit better than 10 kW hours daily.
How we doing so far? -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »So basically you're setting up a system to test panels? That's going to be a bit awkward because not all panels will have the same Voltage/current and so the configuration would differ.
As far as the panels listed are concerned, you would need to run two 36 Vmp in series to have enough Voltage to charge a 48 system, so you're okay with that part. Eighteen 180 Watt panels would be 3240 Watts and might be expected to supply: 3240 * 0.77 / 48 = 52 Amps. One 60 Amp controller should handle that.
The Yingli's Vmp is only 29.5: two in series will not provide enough Voltage for charging a 48 Volt system. That's only 59 Volts, and what with one thing and another there may not be enough to reach full charge (panels heat up = Voltage goes down, wire consumes some). You can't run four in series either, as the Voc would exceed the TriStar's input limit. Any chance of getting one more and having three strings of three? Otherwise the eight 235 Watts would be 1880 Watts and supply about: 1880 * 0.77 / 48 = 30 amps peak charge current. Together with the others this would be over 80 amps current, enough for 800 Amp hours of battery (around 19 kW hours max). You must use an MPPT controller with these panels due to their odd Vmp, and the others would definitely benefit from one as well.
Potential AC Watt hours from the first array: 3240 * 4 * 0.52 = 6.7 kW hours. From the second: 1880 * 4 * 0.52 = 3.9 kW hours. A bit better than 10 kW hours daily.
How we doing so far?
Yes we will be testing the mounting systems for different panels, although the configurations of the panels themselves won't change . I agree that changing the configuration could (WOULD) mess things up electrical-wise.
It's good to see that the Lumos panels will work in the configuration I presented. The problem with the Yingli panels was expected, and I agree. The Morningstar string calculator has an error in the coding apparently, for on of the equations (a< b) was incorrect. Although I'm not looking at the calculator at this moment, I'm positive that the measurement was for the Vmp. I believe we can get 9 Yingli panels, so we will wire them 3x3 (3 strings of 3 panels in series each string).
Also, I'm glad to know that the Tristar MPPT-60 charge controllers will work better. I will change the controllers to the MPPT instead then.
Also, I meant to write that we would have approx 17.5 kWh available (although now I see it's indeed 19 kWh) although we would not replace this much energy (as you wrote above).
So far so good! Everything is as expected Thank you once again or your invaluable input. -
Re: Off Grid System Verification - Please Help!Since we will mainly be running lights on the system (although there are many of them) I figured that the Outback 3048T would be sufficient to suit our needs. This inverter will supply power to a breaker box, which will in turn be wired up to the grid in case of lack of sun (cloudy days for a week). An AC disconnect will be between the breaker box and the grid, so we can switch between the power sources as needed.
My advice is to put the inverter on a midnite Epanel (stretched version). You can buy it prewired with all the AC and DC circuit breakers, shunt for pentametric, surge protectors, bypass switch, etc. Just screw it to the wall, hook up the batteries, controllers, AC in, AC out, and pentametric.
You plan to wire the grid to a transfer switch at the AC panel? Not needed... the outback has an AC input. Transfer switch is built in.
My advice is to hire a certified solar installer with experience in off grid systems.An electrician will be doing all the wiring.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!My advice is to put the inverter on a midnite Epanel (stretched version). You can buy it prewired with all the AC and DC circuit breakers, shunt for pentametric, surge protectors, bypass switch, etc. Just screw it to the wall, hook up the batteries, controllers, AC in, AC out, and pentametric.
You plan to wire the grid to a transfer switch at the AC panel? Not needed... the outback has two AC inputs, one for grid and the other for the generator. Transfer switch is built in.
--vtMaps
So if I were to use the Midnite E-Panel, I believe the Stretched Aluminum MNE175AL-PLUS is correct for the inverter I listed, this would replace the AC disconnect? In addition, it would be automated in respect to transferring the energy input between the inverter and grid?
I just want to make sure that I'm reading the information correctly. If so, I can't see why I wouldn't invest in this, especially since it's prewired. Could I still install an AC disconnect in order to protect the workers on the grid if necessary, or does the E-Panel detect current from the grid and prevent backflow? -
Re: Off Grid System Verification - Please Help!
Yes.So if I were to use the Midnite E-Panel, I believe the Stretched Aluminum MNE175AL-PLUS is correct for the inverter I listed, this would replace the AC disconnect?In addition, it would be automated in respect to transferring the energy input between the inverter and grid?
<snip>
Could I still install an AC disconnect in order to protect the workers on the grid if necessary, or does the E-Panel detect current from the grid and prevent backflow?
The Outback (not the Epanel) takes care of the interconnection with the grid. The outback and Epanel are safe and UL listed. They cannot backfeed the grid. Unlike a grid-tie system you do not need permission from the utility to commission this system.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!
Here's a link to get you started. Note that these systems include the outback inverter and a midnite controller. I believe that you can buy them without the controller. They come in both grid-tie and off-grid flavors.
http://www.solar-electric.com/ouinsy.html
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!Yes.
The Outback (not the Epanel) takes care of the interconnection with the grid. The outback and Epanel are safe and UL listed. They cannot backfeed the grid. Unlike a grid-tie system you do not need permission from the utility to commission this system.
--vtMaps
Alright it's good to know that they are incapable of backfeeding the grid. And yes we didn't plan to feed the grid in any way, but I just wanted to ensure the safety of the grid and those working on it. I didn't think there would be a problem, but better safe than sorry
For the rest of the system (wiring/compatability of parts) what are your thoughts? -
Re: Off Grid System Verification - Please Help!
Steve, I corrected my post #6. The outback only has one AC in (generator or grid). If you want a generator you will need to add a transfer switch before the Outback. The transfer switch (can be automatic) will disconnect the grid when the generator is on.
You will still use the transfer switch in the Outback. When the Outback senses AC (from either source) it will pass the AC through to the loads and will convert itself to a battery charger.
If you want to run your loads off of solar & battery just flip the 'AC in' breaker on the Epanel to the off position.
Sorry for the previous wrong info
I am off grid and what you are doing is most unusual (as Cariboocoot pointed out in post #2). Most folks who want batteries on grid use the Outback grid-tie inverter.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!Steve, I corrected my post #6. The outback only has one AC in (generator or grid). If you want a generator you will need to add a transfer switch before the Outback. The transfer switch (can be automatic) will disconnect the grid when the generator is on.
You will still use the transfer switch in the Outback. When the Outback senses AC (from either source) it will pass the AC through to the loads and will convert itself to a battery charger.
If you want to run your loads off of solar & battery just flip the 'AC in' breaker on the Epanel to the off position.
Sorry for the previous wrong info I am off grid and what you are doing is most unusual (as Cariboocoot pointed out in post #2). Most folks who want batteries on grid use the Outback grid-tie inverter.
--vtMaps
We were actually thinking of wiring the generator up to the batteries, so that it would simply add a charge if needed to prevent sulfation (for example, if we need to do maintenance on the solar array and disconnect it for a period of time). Would this work instead?
I realize that this is a very unusual request, as most people want the most cost-effective solution to their energy needs. This does NOT fall in that category at all haha :P
For wiring, what AWG wire should I use between the panels and combiners, combiners and controllers, controllers and batteries, batteries and inverter, and inverter to loads? I have a 100' run between the battery bank and the panels, and I was thinking of having the charge controllers at the other end of the panels so the higher voltage would prevent losses. Is this thinking correct, or should I have the controllers right next to the combiner boxes? -
Re: Off Grid System Verification - Please Help!
Something you might want to consider is an AC bypass circuit for the inverter, so if you do have to shut it all down whatever loads you run off the inverter can be run from the grid instead. That would require a transfer switch on the OUTPUT side of the inverter, switching loads between inverter source and grid source.
You are right about the Voltages and losses. Keep the controllers close to the batteries.
That 100' run to the controllers from the arrays is something of a problem. The Lumos panels will be running 48 Volt @ 9*5 = 45 Amps. That would call for a horrible 2 AWG wire link to the controller. I'll suggest upping the Voltage at the array (at the cost of some conversion efficiency in the controller), but to do that you will need a MidNite Classic 200 controller to be able to handle the increased Voc potential. Then you could run 3 in series * 6 parallel strings and utilize 8 AWG wire for the run with just over 3% loss at maximum power. (Array changes from 89.6 Voc 72 Vmp 45 Imp to 134.4 Voc 108 Vmp 30 Imp.) -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »Something you might want to consider is an AC bypass circuit for the inverter, so if you do have to shut it all down whatever loads you run off the inverter can be run from the grid instead. That would require a transfer switch on the OUTPUT side of the inverter, switching loads between inverter source and grid source.
You are right about the Voltages and losses. Keep the controllers close to the batteries.
That 100' run to the controllers from the arrays is something of a problem. The Lumos panels will be running 48 Volt @ 9*5 = 45 Amps. That would call for a horrible 2 AWG wire link to the controller. I'll suggest upping the Voltage at the array (at the cost of some conversion efficiency in the controller), but to do that you will need a MidNite Classic 200 controller to be able to handle the increased Voc potential. Then you could run 3 in series * 6 parallel strings and utilize 8 AWG wire for the run with just over 3% loss at maximum power. (Array changes from 89.6 Voc 72 Vmp 45 Imp to 134.4 Voc 108 Vmp 30 Imp.)
I thought the Outback inverter has a switch built in that I could just swap between the grid power and the power from the batteries. I need another transfer switch in addition to this one? I was thinking of having an AC switch in between the inverter and the grid. This would be in the 'off' position normally, but switched to 'on' in order to pull energy from the grid. Would this work?
Also, could I have a Midnite Classic 200 Controller on the Lumos panels and a Tristar 60-MPPT on the Yingli panels? Or would I need to switch the Tristar over to a Midnite controller? -
Re: Off Grid System Verification - Please Help!I thought the Outback inverter has a switch built in that I could just swap between the grid power and the power from the batteries. I need another transfer switch in addition to this one? I was thinking of having an AC switch in between the inverter and the grid. This would be in the 'off' position normally, but switched to 'on' in order to pull energy from the grid. Would this work?
Also, could I have a Midnite Classic 200 Controller on the Lumos panels and a Tristar 60-MPPT on the Yingli panels? Or would I need to switch the Tristar over to a Midnite controller?
Here's the thing: the OB runs loads off the inverter until it senses AC present at the AC IN. Then the loads are switched to that and the inverter goes in to charge mode. But if you have to, for whatever reason, disconnect the inverter from the batteries the AC will not pass through the inverter: the default setting on the built-in transfer switch is 'inverter power'. No batteries = no function, even if grid power is present at AC IN. Sometimes this is a problem.
Yes you can mix charge controller brands/types. They don't really care as long as the parameters are set the same. You pick one as the "main" controller and adapt the other one to it. In this case you'd set things up around the TriStar as the MidNite is far more adaptable. -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »Something you might want to consider is an AC bypass circuit for the inverter, so if you do have to shut it all down whatever loads you run off the inverter can be run from the grid instead. That would require a transfer switch on the OUTPUT side of the inverter, switching loads between inverter source and grid source.
That bypass switch is built into the Midnite Epanel. It is two AC breakers, one turned upside down, and both connected by a mechanical interlock. All UL listed.SteveG wrote:I thought the Outback inverter has a switch built in that I could just swap between the grid power and the power from the batteries.
To use battery power, just flip the 'AC in' breaker on the Midnite Epanel
If you need to remove the inverter for servicing, just flip the bypass switch on the Epanel. The AC will pass through the Epanel to your AC loads.Cariboocoot wrote:But if you have to, for whatever reason, disconnect the inverter from the batteries the AC will not pass through the inverter4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »Here's the thing: the OB runs loads off the inverter until it senses AC present at the AC IN. Then the loads are switched to that and the inverter goes in to charge mode. But if you have to, for whatever reason, disconnect the inverter from the batteries the AC will not pass through the inverter: the default setting on the built-in transfer switch is 'inverter power'. No batteries = no function, even if grid power is present at AC IN. Sometimes this is a problem.
Yes you can mix charge controller brands/types. They don't really care as long as the parameters are set the same. You pick one as the "main" controller and adapt the other one to it. In this case you'd set things up around the TriStar as the MidNite is far more adaptable.
I understand. And a bypass switch on the output of the OB would circumvent this problem entirely. Since we may want to do maintenance at some point, we will have to put this in the final design.
Glad to know that we can mix and match, if we ever add to the system (additional batteries, panels, and controllers). Settings will have to be decided on/explained to me after the system is worked out in its entirety. Although I saw a table that had the correct settings somewhere on the forum. I'll have to check later.
So the 8 AWG will work between the combiners and the charge controllers. Would I use 8 AWG for the other connections as well (except between the batteries, which will most likely be 4 AWG?)?
So it looks like the arrays will be 3x3 (Yingli) and 6x3 (Lumos). That should not be a problem at all. -
Re: Off Grid System Verification - Please Help!We were actually thinking of wiring the generator up to the batteries, so that it would simply add a charge if needed to prevent sulfation (for example, if we need to do maintenance on the solar array and disconnect it for a period of time). Would this work instead?
Well, you could do that, but you would need to buy a freestanding battery charger. If you run the generator through the Epanel/Outback the Outback will become a battery charger and will pass through the generator output to your loads. Of course, the generator needs to be large enough to power your loads AND charge your batteries at the same time. The Outback is pretty clever about this. If your AC loads are too large, the outback will throttle back its charger to avoid overloading your generator.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!
Now I'm confused, as you are both saying two different things entirely haha. So will the E-Panel be able to regulate the energy, or should I install a switch as I mentioned above?
From what I can read on the product page (http://www.solar-electric.com/mne250al-plus.html) it would seem as if the disconnects are already in place to automatically switch (as vtmaps said). -
Re: Off Grid System Verification - Please Help!Now I'm confused, as you are both saying two different things entirely haha. So will the E-Panel be able to regulate the energy, or should I install a switch as I mentioned above?
The Epanel/Outback only accepts one AC input. The only thing you need to add is a transfer switch so that you can choose between grid and generator for your AC input to the Epanel/Outback.
Cariboocoot is an Outback whiz, but he was not considering the bypass switch on the Epanel when he gave you conflicting advice. Check out Midnite's website.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!The Epanel/Outback only accepts one AC input. The only thing you need to add is a transfer switch so that you can choose between grid and generator for your AC input to the Epanel/Outback.
Cariboocoot is an Outback whiz, but he was not considering the bypass switch on the Epanel when he gave you conflicting advice. Check out Midnite's website.
--vtMaps
So I can connect both the inverter and the grid to the E-panel? So I can switch between them to power my loads? Sorry my question was not very focused -
Re: Off Grid System Verification - Please Help!
Sorry, Steve; didn't realize you had decided to go with the MidNite E-panel. It has the inverter bypass just as vtMaps says. Can be quite a convenience. -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »Sorry, Steve; didn't realize you had decided to go with the MidNite E-panel. It has the inverter bypass just as vtMaps says. Can be quite a convenience.
No problem. I probably should have brought that up when you were offering your suggestions
As for the wiring, do those sizes look good in your opinion for the various connections? Or would you suggest something different? -
Re: Off Grid System Verification - Please Help!
Wire sizing is mainly a matter of being able to handle the expected current at Voltage over the distance without too much power loss. Sounds simple, until you put it in practice.
For instance the 8 AWG is what I sized for the array to the controller, correct? But the output of the controller is going to be lower Voltage, higher current, yet shorter distance. If it's a 60 Amp charge controller the wire has to be large enough to handle that much current. This means 6 AWG in my book. That will not only handle the current but keep the V-drop to a minimum even up to 30 feet (on a 48 Volt system). Note that there should definitely be a breaker or fuse/disconnect sized to handle that current on the positive lead.
The DC to the inverter has to again handle the maximum expected current. Now some will argue this is at the surge rating, but since the surge is not continuous my opinion is that it should be at the maximum continuous power: 3600 Watts @ 48 Volts or 75 Amps. That means a minimum wire size of 4 AWG and frankly 2 AWG is better. Keeping the battery cables short is a good idea too, even though technically the 2 AWG would handle 75 Amps @ 48 Volts on a distance up to 60 feet. Minimizing V-drop on the DC of the inverter is important (critical on 12 Volt systems). No one ever regretted putting in the largest wire they could fit.
The AC wiring is all standard practice stuff you are probably already familiar with. -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »If it's a 60 Amp charge controller the wire has to be large enough...
<snip>
Note that there should definitely be a breaker or fuse/disconnect sized to handle that current on the positive lead.
That circuit breaker is included in the prewired Epanel.
Steve,
All of the prewired Epanels that I know about now come with one Midnite Classic controller. Personally, I would take a Midnite controller over the morningstar that you mentioned in the OP. If you do order an Epanel without the Midnite controller, be sure to order a DC GFP to be wired into the Epanel (the Midnite controller does not need an external GFP because the GFP is built into the controller. The morningstar does need an external GFP).
Also, in your OP you indicated that you had two arrays and wanted two controllers. One nice thing about the Midnite panels is that they are roomy enough to allow some customization (such as room for extra breakers for a second controller). Check with Midnite or NAWS to see if you can order a prewired Epanel with two controllers.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Re: Off Grid System Verification - Please Help!Cariboocoot wrote: »Wire sizing is mainly a matter of being able to handle the expected current at Voltage over the distance without too much power loss. Sounds simple, until you put it in practice.
For instance the 8 AWG is what I sized for the array to the controller, correct? But the output of the controller is going to be lower Voltage, higher current, yet shorter distance. If it's a 60 Amp charge controller the wire has to be large enough to handle that much current. This means 6 AWG in my book. That will not only handle the current but keep the V-drop to a minimum even up to 30 feet (on a 48 Volt system). Note that there should definitely be a breaker or fuse/disconnect sized to handle that current on the positive lead.
The DC to the inverter has to again handle the maximum expected current. Now some will argue this is at the surge rating, but since the surge is not continuous my opinion is that it should be at the maximum continuous power: 3600 Watts @ 48 Volts or 75 Amps. That means a minimum wire size of 4 AWG and frankly 2 AWG is better. Keeping the battery cables short is a good idea too, even though technically the 2 AWG would handle 75 Amps @ 48 Volts on a distance up to 60 feet. Minimizing V-drop on the DC of the inverter is important (critical on 12 Volt systems). No one ever regretted putting in the largest wire they could fit.
The AC wiring is all standard practice stuff you are probably already familiar with.
Thank you very much Cariboocoot. Do you happen to know if any of this wiring would be included in a prewired E-Panel? By the name pre-wired, I assume that the wiring between the controller and the inverter is already done. However I assume the rest (array to controllers, controller to battery, battery to inverter) is not included and would need to be purchased. Is this correct?That circuit breaker is included in the prewired Epanel.
Steve,
All of the prewired Epanels that I know about now come with one Midnite Classic controller. Personally, I would take a Midnite controller over the morningstar that you mentioned in the OP. If you do order an Epanel without the Midnite controller, be sure to order a DC GFP to be wired into the Epanel (the Midnite controller does not need an external GFP because the GFP is built into the controller. The morningstar does need an external GFP).
Also, in your OP you indicated that you had two arrays and wanted two controllers. One nice thing about the Midnite panels is that they are roomy enough to allow some customization (such as room for extra breakers for a second controller). Check with Midnite or NAWS to see if you can order a prewired Epanel with two controllers.
--vtMaps
If I were to get a second Midnite controller over the Tristar MPPT that I originally mentioned, would you recommend the Midnite Classic 150 controller for the 3x3 Yingli panels? Cariboocoot already recommended the Midnite Classic 200 controller for the Lumos. Or would the Voc be high enough to go to another 200 controller? -
Re: Off Grid System Verification - Please Help!
Does anyone have any thoughts for the questions I posed above? (E-Panel wiring, controller recommendations, etc) -
Re: Off Grid System Verification - Please Help!So the 8 AWG will work between the combiners and the charge controllers. Would I use 8 AWG for the other connections as well (except between the batteries, which will most likely be 4 AWG?)?
So it looks like the arrays will be 3x3 (Yingli) and 6x3 (Lumos). That should not be a problem at all.
Is that your question Steve?
To evaluate wiring, really need loads/array Vmp and Imp configuration (and Isc). Also distance for wire run. Plus battery bank voltage.
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: Off Grid System Verification - Please Help!Is that your question Steve?
To evaluate wiring, really need loads/array Vmp and Imp configuration (and Isc). Also distance for wire run. Plus battery bank voltage.
-Bill
I think Cariboocoot handled all my wiring needs up in his post above (post #24). What I was looking to have answered was post #26. -
Re: Off Grid System Verification - Please Help!
What are the solar panel specifications (Voc/Vmp/Imp), array configuration (and if you plan on expanding), and the battery bank voltage and AH capacity... I think I am getting a bit lost on your proposed system configuration.
And cable lengths.
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: Off Grid System Verification - Please Help!What are the solar panel specifications (Voc/Vmp/Imp), array configuration (and if you plan on expanding), and the battery bank voltage and AH capacity... I think I am getting a bit lost on your proposed system configuration.
And cable lengths.
-Bill
Array:
( 18 ) Lumos Modules LSX180-72M - Pmpp 180W, Voc 44.8V, Isc 5.29A, Vmpp 36V, Impp 5A . There will be 6 strings of3 each.
( 9 ) Yingli Solar Panels YL235P-29b - Pmpp 235W, Voc 37.0V, Isc 8.54A, Vmpp 29.5V, Impp 7.97A. There will be 3 strings of 3 each.
As for expansion, there will be no expansion for this system.
Battery Bank:
The battery bank will have one 48V 804Ah forklift battery.
Wiring:
Some wiring will be in the Midnite E-Panel Stretched Aluminum 250. There will be 100' lengths of 6AWG running from the combiner boxes to the charge controllers. And the rest of the cable lengths will be as short as possible. I don't have specific lengths because the system isn't yet finalized or laid out yet. I also don't know what wiring is included with that E-Panel, thus waiting for the response on post #26.
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