positive ground solar tied to neg. ground truck?

[herm]

i ended up with a "positive ground" solar charge controller. I have it all setup to charge the house battery and have my loads set up through a fuse block on the load pins of the controller. I am also powering some clearance lights with the truck trailer plug. the camper has a chassis ground common to all the interior and clearance lights.

do i need to install a relay between the clearance light wire of the truck harness and the clearance light circuit of the camper? should be very straight forward to wire up. I can run a ground from my trailer plug to the tail lights to keep that circuit isolated from the camper circuit.

or... am i crazy, and i can just hook up the 12v hot from the trailer plug to the battery for charging and common ground everything and not worry about it?
controller is renogy PWM30CC w/ one of their 100 watt panels.

 

[herm]

there is no chassis ground on the charge controler, the mounts are all plastic with the plastic case. I really don't know why one would have to run it positive ground.... its all floating point anyway... I i have it wired as such right now and it is charging the battery fine, lights work etc... i don't have it on the truck yet or the tail lights/clearance lights wired. if i change it to positive ground (chassis connected to positive battery) Will i get a voltage when measured between the camper exterior and the truck bed? am i stupid and should just buy a different controller? ( and delete this thread so i can sell it to someone!) :coffeedrink: from what i read on a solar power forum, positive ground allows the panel to work at a slightly higher efficiency because it prevents charge from "building up" in the cells over long periods of time. if this is the only reason then i am inclined to keep it set up with the regular ground.

 

[228B]

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Only curious, to which solar power forum do you refer?

 

[calicamper]

there is no chassis ground on the charge controler, the mounts are all plastic with the plastic case. I really don't know why one would have to run it positive ground.... its all floating point anyway... I i have it wired as such right now and it is charging the battery fine, lights work etc... i don't have it on the truck yet or the tail lights/clearance lights wired. if i change it to positive ground (chassis connected to positive battery) Will i get a voltage when measured between the camper exterior and the truck bed? am i stupid and should just buy a different controller? ( and delete this thread so i can sell it to someone!) :coffeedrink:View attachment 291840 from what i read on a solar power forum, positive ground allows the panel to work at a slightly higher efficiency because it prevents charge from "building up" in the cells over long periods of time. if this is the only reason then i am inclined to keep it set up with the regular ground.

I read about this a little when I was building my little solar power system. I found it pretty confusing given its not really the norm today but that type of circuit was used in the past. I kept my system isolated from the vehicle in my case trailer and so far it seems fine. I would not ground the system to the vehicle like a vehicle electrical system through the controller. In my case the controller basically has three inputs. Pos neg to the battery, Pos Neg to the solar, and Pos Neg as a powered circuit out of the controller for a street lamp. I kept it all isolated and tied all my lighting neg to a bar and run the pos through a fuse block. Just to be safe I fused the primary from the battery and the primary power out from the controller which was probably over kill but why not hardly cost anything to fuse those. So far its been great.

 

[herm]

http://forum.solar-electric.com/for...sitive-ground-vs-negative-ground-solar-panels

this thread. I cross posted this question on another tech forum as well.

http://forums.anandtech.com/showthread.php?t=2437050

Cali: that is how mine is set up too, using the neg. bus on the blue sea fuse block. did you connect your loads via the battery or via the load port on the controller?

 

[calicamper]

http://forum.solar-electric.com/for...sitive-ground-vs-negative-ground-solar-panels

this thread. I cross posted this question on another tech forum as well.

http://forums.anandtech.com/showthread.php?t=2437050

Cali: that is how mine is set up too, using the neg. bus on the blue sea fuse block. did you connect your loads via the battery or via the load port on the controller?

I contemplated doing the load from the battery but.. I really liked the idea of leveraging the controllers ability to both show consumption and its ability to kill power at 11.4volts to avoid damaging the battery by running it too low. Granted its a 20amp max through the controller but our needs are very small at max we might be pulling 10-15amps so I decided to try using the output side of the controller to leverage the management aspect. So far its been pretty slick. I also don't worry too much about a light being left on by the kids etc. Given the controller will step in if we run it too low etc. I did not put a master kill switch on the system. If I were not using the load side of the controller I would probably for sure put a master kill switch so I could knowingly isolate the battery from load etc.

 

[dwh]

According to this page:

http://www.renogy-store.com/30-amp-charge-controller-p/ctrl-pwm30.htm

"Please Note:This is Positive Ground Controller. If grounding is necessary, it must be completed on the positive line. If the controller is to be used on a vehicle which has battery negative on the chassis, loads connected to the controller must not have an electrical connection to the vehicle body.
If you want to connect the solar system to a negative ground battery bank, you can choose ViewStar Charge Controller or MPPT Charge Controller."


That's a PWM30.

The manual for the PWM30CC doesn't appear to mention positive ground at all (unless I overlooked it, but I read it twice and also did a search in the document):

http://renogy.com/wp-content/uploads/2014/07/PWM1030CC-Manual.pdf


So if you have a PWM30CC, then maybe it's not a positive ground.

 

[herm]

They are the same thing it apears

 

[unseenone]

There is nearly immeasurable improvement if there is any at all. Why would you want to over complicate things. You could compensate for any shortage in efficiency with better panels, more panels, etc. Just curious why even go this route..

 

[herm]

did not plan on it, did not know from where i bought the kit that it would be positive ground. its all set up negative right now and working fine, if i blow the controller or something i will just have to replace it, though for the life of me i cant figure out why the controller and its plastic case and no extra ground point would even care.

 

[herm]

i am going to keep the relay and not charge from the truck. just in case, but i will be grounding the negative to chassis of the camper. when installed on the truck, ill check voltage/current all the ways i can think of just to be sure.