Solar Controller questions

AzRVSolar

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Joined
May 23, 2021
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5
I am new to this forum, my previous forum experience having been on RV specific forums, but one poster suggested that this was a better place for solar questions than any RV specific location and I suspect that is right. I had posted this specific question on the RV forum but got only a few responses and am hoping that I will have better luck here. This is largely copied from that original post.

We have gone from a 30 amp Zamp solar controller on our previous RV to a Thor Manufacturing (not Thor Industries) 30 amp solar controller (Amazon link here) in our new RV. Both are PWM but I find myself puzzled by some of the setup options and the manual is only of limited help. And the "technical support" people do not return calls, which might mean that they know even less than I about the setup settings, so I thought I would ask some general questions here. Not about this particular solar controller (which is rare enough to not even have any Amazon reviews) but rather general in nature.

The Zamp controller has 4 wires, 2 to the solar panels and 2 to the batteries, but the Thor Manufacturing has 6 wires, 4 hooked up as with the Zamp controller but 2 to the "Load". That puzzles me since I would have thought that the load was the combined electric usage of the RV and that that would come from the battery, not the solar controller. What is the purpose of the load connections on the solar controller? If it is to measure the amount of power going to the load does it do that for all of the used power?

I thought it would be relatively easy to replace the solar controller, either with another PWM or an MPPT if I could find one that would fit in the space, but the Zamp that I am familiar with only has the 4 connections and I am not sure what the result of not hooking up the "load" wires might be, and the same issue exists for the MPPT controllers that I saw. In addition this solar controller is mall and it is not clear that any other similar controller will fit in the space.

My last question is whether anyone is familiar with a well supported 6 wire 30 amp PWM solar controller that I might use to replace this one if I find I can't get this one to work properly. If it makes any difference the new RV came with 400 watts of rooftop solar and I had them move the 200 AH Battleborn Lithium batteries and the 30 amp Victron DC-DC Charger from my old RV to this one, so any solar controller I used would have to have a Lithium profile.

Any help would be appreciated.

Just in case anyone is interested, the one question I had about this particular solar controller was what the proper Load Mode would be for normal usage. The manual lists 18 of them, and I don't even know what Load Modes are. Of the 18 modes listed the only 2 that made any sense to me were the Manual and Default values. I initially set it up as Default thinking that a default value was probably a good initial choice but the Manual Mode description says that it allow the user to turn the load on and off manually. I don't see any way to do that (there is no ON and OFF entries or buttons) and I don't know which would be the initial setting for Manual, but today I changed the setting to Manual assuming that it would be no worse than Default and might turn the "Load" connections (whatever that means) off.
 

fratermus

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Mar 19, 2021
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262
the Thor Manufacturing has 6 wires, 4 hooked up as with the Zamp controller but 2 to the "Load"

LOAD outputs are something of a vestigal tail, a feature from when solar charge controllers were used to control lighting after dark, etc. In practice the LOAD outputs on controllers are ignored most of the time.

I suspect you don't need a 6wire controller; I've never even seen the term used before this thread. It's conceivable Thor is using the outputs for something meaningful. You could pull one of the LOAD wires out and see if anything breaks. My instinct is if Thor is using the LOAD output you could just combine it with the other battery connections.

it is not clear that any other similar controller will fit in the space.

PWM controllers tend to be smaller than MPPT, although the Victron MPPT controllers are packaged fairly small. If you post the actual size requirement somebody might chime in with a good candidate.

I am a fan of MPPT for lead-chemistry batteries that receive only solar charging, but with Li and DC-DC charging I'm not convinced MPPT passes the cost/benefit test, particularly when size is factored in.

any solar controller I used would have to have a Lithium profile.

IMO, any controller with configurable setpoints is lithium-compatible. Plug in whatever values the battery manufacturer (BB) suggests. The only lithium-specific feature one might want is low-temp cutoff (rare in a controller):

* if the BMS lacks it
* and if one will be camping in freezing weather
* without a means of warming the battery.
 

AzRVSolar

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Joined
May 23, 2021
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PWM controllers tend to be smaller than MPPT, although the Victron MPPT controllers are packaged fairly small. If you post the actual size requirement somebody might chime in with a good candidate.

That is a good idea.

The space is approximately 7 x 4.5 x 1.75 and the Thor Manufacturing controller that is in there is a bit narrower and not quite that high. But it sits in a panel with a lot of other displays and controls and there is not a lot of space for the solar controller. In addition there is a door that closes so the depth of 1.75 is pretty much it.

IMO, any controller with configurable setpoints is lithium-compatible. Plug in whatever values the battery manufacturer (BB) suggests. The only lithium-specific feature one might want is low-temp cutoff (rare in a controller):

* if the BMS lacks it
* and if one will be camping in freezing weather
* without a means of warming the battery.

I think that is probably right, but most of the controllers that I saw on Amazon gave no information about being able to set values, and you had to live with what you got. That might be acceptable if they had Lithium profiles as you could probably count on the settings being reasonable, but many of them did not.

The Thor that is in our new (well, new to us) RV has some configurable parameters for Lithium, and one of those is for the charging voltage so if it works properly it is probably OK. I was mostly thrown by the Load Mode settings as the manual, which I have now read several times, is really not at all clear about the proper settings for that. You were very helpful, and I thank you for the clarity of your response as the purpose of that function is much clearer than it was before. I still don't know the proper setting for that function but I am no longer concerned about it.

The only solar controllers that I saw on Amazon that I am even a little familiar with were the Renogy and Zamp models. I know the Zamp 30 am solar controller because it was in our previous RV, and I am familiar with Renogy as a company, if not with the controller itself.
 

fratermus

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Joined
Mar 19, 2021
Messages
262
I think that is probably right, but most of the controllers that I saw on Amazon gave no information about being able to set values,


I just looked at the first page of search results on I got on Amazon for 30A MPPT:

* the victron is fully adjustable by app
* the renogy specifically said "adjustable parameters" in the listing title
* the 11 epever units are fully adjustable by remote display (MT50), PC.
* the SUNYIMA is fake mppt, which one might guess from the $25 price if nothing else
* I didn't dig much to see about the Newpowa or Beleeb, though the manuals could reveal the info
 

AzRVSolar

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Joined
May 23, 2021
Messages
5
I just looked at the first page of search results on I got on Amazon for 30A MPPT:

* the victron is fully adjustable by app
* the renogy specifically said "adjustable parameters" in the listing title
* the 11 epever units are fully adjustable by remote display (MT50), PC.
* the SUNYIMA is fake mppt, which one might guess from the $25 price if nothing else
* I didn't dig much to see about the Newpowa or Beleeb, though the manuals could reveal the info

I was looking at the PWM controllers and only those that fit into the space available. As far as I can tell none of the MPPT solar controllers will fit. Yes, I suppose I could run the wires through the cabinets and store an MPPT controller there, but my first choice would be to make use of the available space and the Victron, as appealing as it might otherwise be, will not fit.

I also need to install a battery monitor because the existing PWM controller appears to base its estimate of the SOC of the battery on the battery voltage and, of course, that varies depending upon the load. Right now, where we are camping, it is showing me everything from 85% to 100% SOC depending on what my wife is using at the time. It would be helpful to actually see the amp flow and have an accurate SOC measurement.
 
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