# Distance Solar Panels from Charge Controller

Registered Users Posts: 22
Will my voltage drop if I run a 100FT MC4 Connection running from my solar panels to my Charge controller?

If my solar panels are 100FT if not further from the charge controller, will I loose Current or Voltage?

How do I calculate that? How can I word that, in a search?

So.. If I didn't want to install solar panels on the roof, and if I had more room in the back yard.. How would I figure that out?

• Solar Expert Posts: 3,009 ✭✭✭✭
Re: Distance Solar Panels from Charge Controller

Hi "312", welcome to the forum.
Some questions - - -
What do you have for solar panels, wattage, voltage etc and how many? Make and model would help.
What do you have for a charge controller? Make and model? MPPT or PWM?
What do you have for batteries, how many, what voltage and AH, and what is the final battery bank voltage?
There will be losses, but depending on a number of things, that loss can be manageable.
• Banned Posts: 17,615 ✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
Will my voltage drop if I run a 100FT MC4 Connection running from my solar panels to my Charge controller?

Most certainly, regardless of array Voltage. How much and whether the drop is 'acceptable' depends on the actual Voltage, current, and wire size as well as distance.
If my solar panels are 100FT if not further from the charge controller, will I loose Current or Voltage?

You will lose Voltage to the controller.
How do I calculate that? How can I word that, in a search?

Voltage drop calculator. A simple one: http://www.powerstream.com/Wire_Size.htm
So.. If I didn't want to install solar panels on the roof, and if I had more room in the back yard.. How would I figure that out?

Figure what out? Your question isn't clear.

Dealing with V-drop is one of the main advantages of MPPT type controllers; by putting panels in series (instead of all parallel) the power comes to the controller as higher Voltage, lower current and less loss is suffered. The controller takes care of adjusting it to proper charging level with minimum power loss.
• Registered Users Posts: 22
Re: Distance Solar Panels from Charge Controller

So basically, I need to have the panels in series & parallel. 24Vdc or higher to the charge controller to account for the voltage drop to the charge controller. So that's what I'll do, Series & Parallel array.

24Vdc by the time it get's to the PWM or MPPT Charge controller will be acceptable for a 12Vdc system.

Gonna start with a Morningstar ProStar 30. Renogy 100W Panels. Trojan AGM 31 (100Ah).
• Banned Posts: 17,615 ✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
So basically, I need to have the panels in series & parallel. 24Vdc or higher to the charge controller to account for the voltage drop to the charge controller. So that's what I'll do, Series & Parallel array.

24Vdc by the time it get's to the PWM or MPPT Charge controller will be acceptable for a 12Vdc system.

Gonna start with a Morningstar ProStar 30. Renogy 100W Panels. Trojan AGM 31 (100Ah).

You can not feed higher Voltage to a PWM type controller: it lacks the needed circuitry to down-convert it to more charge current. All it will do is pass the current available.

In other words two panels with Vmp of 18.9 and Imp of 5.3 in series will be 37.8 Volts but provide only 5.3 Amps on a PWM type controller, whereas on an MPPT type the current will be up to 12.8 Amps on a 12 Volt system.

If you need to overcome long wiring losses you either use an MPPT controller or accept a large loss in power on a PWM type.
• Solar Expert Posts: 5,657 ✭✭✭✭✭
Re: Distance Solar Panels from Charge Controller
In other words two panels with Vmp of 18.9 and Imp of 5.3 in series will be 37.8 Volts but provide only 5.3 Amps on a PWM type controller, whereas on an MPPT type the current will be up to 12.8 Amps on a 12 Volt system.
IF these are the specs for the Renogy panels, you might be okay for 100 feet with 10 gauge wires into an PWM type charge controller. You will have a 10% voltage drop, but since these panels are such high voltage you would end up with a voltage of 16.7 at the charge controller which should be okay. I used 18.7 volts and 10 amps as a likely input max. You might check to see if there are published NOCT values published for these panels.

My figures assume you combine them at the panels and run a single line to the charge controller. You also want the charge controller very near your battery bank

Another option is to place the batteries and the charge controller and inverter next to your panels and run AC current to the point of use. The higher voltage AC current will have much less voltage drop.
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
• Registered Users Posts: 22
Re: Distance Solar Panels from Charge Controller
Photowhit wrote: »
IF these are the specs for the Renogy panels, you might be okay for 100 feet with 10 gauge wires into an PWM type charge controller. You will have a 10% voltage drop, but since these panels are such high voltage you would end up with a voltage of 16.7 at the charge controller which should be okay. I used 18.7 volts and 10 amps as a likely input max. You might check to see if there are published NOCT values published for these panels.

My figures assume you combine them at the panels and run a single line to the charge controller. You also want the charge controller very near your battery bank

Another option is to place the batteries and the charge controller and inverter next to your panels and run AC current to the point of use. The higher voltage AC current will have much less voltage drop.

How do you figure the losses for the voltage drop? I don't know the formula.

Where does the MorningStar state what the maximum voltage it will accept to charge 12Vdc batteries in parallel?

Thanx for the help. I'm aware of the Vmp rating, 18Vdc for the Renogy panels. So.. with a 10% voltage drop, which I don't know how you figured that out, it will come to 16.2Vdc. So that's pretty good I guess.. But if it's cloudy, I'd probably need that extra 1.6Vdc coming from the panels.
• Solar Expert Posts: 494 ✭✭✭
Re: Distance Solar Panels from Charge Controller
How do you figure the losses for the voltage drop? I don't know the formula.

The link cariboocoot listed above works. You have to scroll down past the first table to find the calculator. There are others available online that have options, but that one is good enough.

"Voltage drop calculator. A simple one: http://www.powerstream.com/Wire_Size.htm "
Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
• Solar Expert Posts: 5,657 ✭✭✭✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
How do you figure the losses for the voltage drop? I don't know the formula.
Use a calculator on line, I think Mountain Don said 'Coot had linked to one.
Guest312 wrote: »
Where does the MorningStar state what the maximum voltage it will accept to charge 12Vdc batteries in parallel?
I suspect it's in the specifications somewhere, I'd be comfortable saying the 18.9 volts would be fine.
Guest312 wrote: »
I'm aware of the Vmp rating, 18Vdc for the Renogy panels. So.. with a 10% voltage drop, which I don't know how you figured that out, it will come to 16.2Vdc. So that's pretty good I guess..
I think 'Coot said those panels ran 18.9volts? I know a couple do, DMSolar and some others. He said it and I believed him and punched in 18.7v into the calculator, the calculator gave me the voltage drop and end voltage. I asked about the NOCT values since I think some of the panels are treated to have better flash ratings and they have higher drop during working temperatures, likely just an added expense to make the panels look better and produce even lower % of panel rating... sorry, hate marketing ploys...
Guest312 wrote: »
But if it's cloudy, I'd probably need that extra 1.6Vdc coming from the panels.
It doesn't work like that, typically you will have close to rated voltage with minimal current during cloudy weather.
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
• Registered Users Posts: 22
Re: Distance Solar Panels from Charge Controller

MPPT ! Putting the panels in series & parallel is the only way to do it.

• Registered Users Posts: 22
Re: Distance Solar Panels from Charge Controller
You can not feed higher Voltage to a PWM type controller: it lacks the needed circuitry to down-convert it to more charge current. All it will do is pass the current available.

If you need to overcome long wiring losses you either use an MPPT controller or accept a large loss in power on a PWM type.

YEP. Exactly right. That's the only real way to do it. Put the panels in series & parallel, and be done with it. Buy a nice \$500 MPPT Charge Controller like the Outback FlexMax 60, and voilà.
• Solar Expert Posts: 5,657 ✭✭✭✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
YEP. Exactly right. That's the only real way to do it. Put the panels in series & parallel, and be done with it. Buy a nice \$500 MPPT Charge Controller like the Outback FlexMax 60, and voilà.

Other options have been suggested that have and will work. Lived many years with PWM CC, batteries and inverter under my array, running AC current to my home 80 feet away.

Indeed for 14+ years my charge controller, inverter and batteries have lived in an outside power center, works for me, though I have gone with MPPT charge controllers now. Don't tell me I've been doing it wrong for all these years!
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
• Solar Expert Posts: 5,183 ✭✭✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
Buy a nice \$500 MPPT Charge Controller like the Outback FlexMax 60, and voilà.

Nope, get a KID for about 1/2 of that \$500 from our host.... http://www.solar-electric.com/catalogsearch/result/?q=KID&cat=0

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
• Registered Users Posts: 22
Re: Distance Solar Panels from Charge Controller
westbranch wrote: »
Nope, get a KID for about 1/2 of that \$500 from our host.... http://www.solar-electric.com/catalogsearch/result/?q=KID&cat=0

But 30 Amps is the max.. It seems. It also seems it's just another regular MPPT Charge Controller.. what's the difference, besides it's \$300. Why do they call it KID? Thanks for the link, much appreciated, didn't know about "KID". Have no idea what the difference is, hopping you can shed a little light, or tell me why it's half the price, and why it's called the KID.
• Banned Posts: 17,615 ✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
But 30 Amps is the max.. It seems. It also seems it's just another regular MPPT Charge Controller.. what's the difference, besides it's \$300. Why do they call it KID? Thanks for the link, much appreciated, didn't know about "KID". Have no idea what the difference is, hopping you can shed a little light, or tell me why it's half the price, and why it's called the KID.

Just another regular MPPT controller as opposed to what? An ultra-high Voltage one?
Kid is the 'small' version of the Classic @ 30 Amps as opposed to 80 Amps, hence the name. And two of them can be stacked to work together for 60 Amps if need be. You'd still be at less money (\$285 *2 = \$570 vs. \$610 for a full Classic) but would have slightly less current capacity and fewer advanced features (AUX ports for example).

It points out the need to plan in advance not only your existing system but whatever future practical expansion you may want. If all you need is a basic 30 Amp MPPT, why spend more?

I'm pretty sure I know what I'm talking about, although some people keep telling me otherwise.
• Solar Expert Posts: 5,657 ✭✭✭✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
But 30 Amps is the max.. It seems. It also seems it's just another regular MPPT Charge Controller.. what's the difference, besides it's \$300. Why do they call it KID? Thanks for the link, much appreciated, didn't know about "KID". Have no idea what the difference is, hopping you can shed a little light, or tell me why it's half the price, and why it's called the KID.

FWIW - It's designed by the guys who designed the original outback charge controllers years back, They have some unusual names for things. The company is Midnite, and their 'large' charge controller is the Classic and will handle up to 96amps on a 24 volt system and would likely be the suggested charge controller if you need a higher amperage charge controller.

If the name throws you, get ready for odder names, they make a shunt based charging monitor for the kid and Classic, it's called the Whiz Bang Jr. and is one of the features that set their system apart from most. It comes with the Midnite Classic.

I have no idea what system you want to end up with, but a single 100 amp 12 volt battery won't require more than a Kid, and in general you shouldn't add new batteries to old. Might look at where you want to end up and make out a timeline plan for adding components to get there, often when you're changing batteries is the best time to do this.

Also if you want to discuss your final system size, there might be some cost savings you could look at now, higher voltage systems tend to be more efficient. Changing inverters tends to be expensive. You might want to start with a 24 volt system if you intend to have a moderately sized system.
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
• Solar Expert Posts: 5,183 ✭✭✭✭
Re: Distance Solar Panels from Charge Controller
Guest312 wrote: »
But 30 Amps is the max.. It seems.

That 30Amps would be sufficient to charge a 300Ahr rated battery at a 10% charge rate, (~equivalent to ~3 car batteries)

300Ah x 12V =3600W x 50% derate = 1800Wh (if you were to go to the max depletion before recharging...double that use from 24V system....)

First thing is to match the battery to the loads...

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep