Looking for a new solar charge controller, suggestions?

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Crave

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I currently have 3 100watt panels and have discovered that my charger controller is a positive ground system. I'm looking for a controller that is negative ground solar that I can use a common ground and still monitor the low current items from the controller. I do plan on adding another 100 watt panel so I need a controller that can handle 40A. Also I plan to install a solenoid and have the ability to charge the batteries from my tow vehicle. This upgrade is planned for this fall so any suggestions would be greatly appreciated.
 

MikeRuth

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Optimistic Paranoid said:
Morningstar makes great controllers.  Very High quality.

I second that very much, built tough and solid. I use a TS-45 Myself. 
Mike R
 

John61CT

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Victron MPPT, 75/15 under $100. Would even give you room for expansion if you want to stack voltage serially.
 

Trebor English

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If you have a battery connected to a light bulb it is on.  If you want to turn it off you need to add a switch to open the circuit.  There are two wires.  The red wire connects the battery plus to the light and the black wire connects the battery minus to the light.  To turn off the light you can cut either wire and install a switch.  

My cheap solar controller has the battery plus connected to the solar panel plus all the time.  The battery minus connects to the panel through the switch.  The switch in the controller is full on for bulk and switching on and off for PWM voltage limiting.  The switch is in the minus side because transistors, that are NPN or N-channel are faster, better, cheaper, lower resistance, than the PNP  or P-channel alternatives.  

Renogy has a controller that switches the plus side.  I sent an email with the question: can I connect the solar panel minus side direct to the roof to use the steel roof as the minus conductor saving money on the wire?  The response was that it could work but was not recommended.   

I have a cheap amp hour meter.  I connect it to various places depending on what I want to measure.  When not somewhere else I put it between the solar panel and the controller.  The amp hours passed through it charging tells me how much I used last night as well as how it is all working today.  I have used it with my MaxxAir fan.  Works fine.  

In the original post you say you have a positive ground system.  Is your house battery plus terminal connected to the vehicle chassis?  If all the house wiring is isolated from the vehicle wiring it doesn't matter.  If the two come together bad things could happen.
 

jimindenver

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I have two Morningstar controllers and recommend them.
 

tx2sturgis

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Crave said:
I currently have 3 100watt panels and have discovered that my charger controller is a positive ground system.

Maybe I'm out of the loop on this, but positive ground vehicles and systems have been gone (not newly manufactured as far as I know) since the mid-70's....I find it hard to imagine that a solar controller is positive ground.

If so, it would be for a very narrow market, possibly designed specifically for much older vehicles..or not for vehicle use at all.

Have you got a make and model number and/or a picture you can post of this item?
 

Weight

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There was some conversation about these Renogy positive ground controllers on this forum. Maybe lost threads during the great change over.
 

KathyC

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John61CT said:
Victron MPPT, 75/15 under $100. Would even give you room for expansion if you want to stack voltage serially.

I've been looking long and hard at the Victrons, and they seem to be an amazing value for a smaller MPPT controller.  I'm going with them in our new buildout.  I also like the easy-to-add bluetooth dongle to monitor via tablets/phones.
 

tx2sturgis

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Weight said:
There was some conversation about these Renogy positive ground controllers on this forum. Maybe lost threads during the great change over.

I wonder why they were designed that way....unless maybe they had some ability to do a floating ground...


Or maybe there is some use for them in the oil and gas industry...they use some weird stuff on remote monitoring and telemetry sites...well, weird from our point-of-view....
 

Weight

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MorningStar are still the best value for your dollars.
 

Crave

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tx2sturgis said:
I wonder why they were designed that way....unless maybe they had some ability to do a floating ground...


Or maybe there is some use for them in the oil and gas industry...they use some weird stuff on remote monitoring and telemetry sites...well, weird from our point-of-view....

I suspect it is due to the country in which it was manufactured. Not all countries use good practices in engineering.
 

Crave

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Trebor English said:
If you have a battery connected to a light bulb it is on.  If you want to turn it off you need to add a switch to open the circuit.  There are two wires.  The red wire connects the battery plus to the light and the black wire connects the battery minus to the light.  To turn off the light you can cut either wire and install a switch.  

My cheap solar controller has the battery plus connected to the solar panel plus all the time.  The battery minus connects to the panel through the switch.  The switch in the controller is full on for bulk and switching on and off for PWM voltage limiting.  The switch is in the minus side because transistors, that are NPN or N-channel are faster, better, cheaper, lower resistance, than the PNP  or P-channel alternatives.  

Renogy has a controller that switches the plus side.  I sent an email with the question: can I connect the solar panel minus side direct to the roof to use the steel roof as the minus conductor saving money on the wire?  The response was that it could work but was not recommended.   

I have a cheap amp hour meter.  I connect it to various places depending on what I want to measure.  When not somewhere else I put it between the solar panel and the controller.  The amp hours passed through it charging tells me how much I used last night as well as how it is all working today.  I have used it with my MaxxAir fan.  Works fine.  

In the original post you say you have a positive ground system.  Is your house battery plus terminal connected to the vehicle chassis?  If all the house wiring is isolated from the vehicle wiring it doesn't matter.  If the two come together bad things could happen.

My car and trailer use a negative ground system as a positive ground system has two major drawbacks. One is that when air flows over the vehicle it will deposit electrons and as electricity actually flows from negative to positive this can cause issues with a battery. The second has to due with charged particles of opposite polarity being attracted to one another making a positive ground vehicle literally a dust and salt magnet.

I discovered the issue when I was starting to set up the trailer for charging my batteries from the car alternator, in which case the solar system must be compatible with the negative ground system. The other issue is as I want to save on wire and use a negative ground I would have to purchase a second device to monitor my low amp power output also the auto battery disconnect would be bypassed in the case of low voltage as I would have to bypass the charge controller low amp output side.

P.S.

I call it the low amp output as in comparison to audio equipment and engine starters 40 amp max output is nothing.
 

John61CT

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Crave said:
I suspect it is due to the country in which it was manufactured. Not all countries use good practices in engineering.

There is little objective advantage of negative vs positive ground.

Industry has standardized on negative, so that is now the advantage, just familiarity.

But there must be a reason for bucking the trend, we are just currently ignorant of what that reason may be.

And wrt domestic electric standards, those outside the US in developed nations are superior in both safety and efficiency; we are the redheaded stepchild in that arena.
 

Sabatical

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John61CT said:
Victron MPPT, 75/15 under $100. Would even give you room for expansion if you want to stack voltage serially.
It appears as though the 75/15 is only good for 200w @ 12v, unless i misread the info. For a small system or a setup with multiple small systems, this would be a good choice. I'll be keeping this one on my list for small scale applications.

Sent from my SCH-I435 using Tapatalk
 

jimindenver

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The Victron 75/15 is rated for 220w at 12v. As long as it can be over paneled you would loose some watts/amps in peak conditions mid day. The loss would be limited by a few factors including the fact that a 100 watt panel will never see 100 watts even if you were tracking the sun and mounted flat they will see even less. There is also the fact that many times your system may be past the bulk stage by mid day meaning the battery will be self limiting the amount of power it can accept by then anyways. The amount of loss would depend on conditions such as altitude where you would loose the most at high altitude on a cold day. That said the over paneling would be of benefit early on when the excess panel would provide more power when you need it most. I can say I dislike internal temperature compensation because charge controllers generate heat.

For not much more money you could go with a Tracer MPPT 20 or 30 amp.
 

John61CT

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jimindenver said:
I dislike internal temperature compensation because charge controllers generate heat.

For not much more money you could go with a Tracer MPPT 20 or 30 amp.
AKA EPSOLAR now, or Epever?

Xantrex also used to be "Trace"?

Are these on par with Midnight, Morningstar, Blue Sky?

And I don't see at what size in the line Victron goes to an external sense wire. I suspect those Dutch engineers may have factored in the internal offset issue, maybe "good enough"?
 

jimindenver

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AKA EPSOLAR now, or Epever?

You are correct that these are the names behind the Tracer series of controllers. They are produced under a number of names including Renogy. Are they on par with the other big names? That is subjective I suppose. I have known a number of people that use them without complaint. That is pretty good considering Morningstar released many TS-MPPT-60s with firmware issues including my own and their newest 30a MPPT controller was released with issues, you never know what is behind the name big or small. In any event the biggest objective is to meet your needs and that means considering all of the options.
 

tripper

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Sabatical said:
It appears as though the 75/15 is only good for 200w @ 12v, unless i misread the info. For a small system or a setup with multiple small systems, this would be a good choice. I'll be keeping this one on my list for small scale applications.

Sent from my SCH-I435 using Tapatalk

You could use two Victron 75/15's, one for each pair of 100 watt panels. The Victron is available for under $100.  Victron does have larger MPPT controller too if you just want to use one, two would be a good hedge against partial shading of a panel or just a nice redundancy in case of failure. I have a couple of the Victrons and they work very well and I believe they are the least expensive, most compact and best user interface of all the controllers out there. They are full programmable with a very nice app on your cell phone (need additional Bluetooth cable).

I like that the entire solar setup can be hidden, I have h controllers right next to the battery for efficiency and the temp monitor I right by the battery.  There is no indication inside my rig that I have a controller, just pull it up on android when I need to see it.  Keep a full history too. Victron routinely upgrades the software and occasionally the ROMs too.  In my opinion they are quite a bit more advanced than the other popular MPPTs.

[img=640x480]https://www.sparelys.no/bilder/victron-blue-solar-app.gif[/img]
 

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