PWM to MPPT Solar Controller Upgrade

[1woodward1]

2023 Micro Minnie 1720fb. Looking to upgrade my controller from pwm to mppt. I have confirmed that my converter is auto detect. I have the stock wet cell lead acid 81 Ah and 190w solar panel. Eventually, I will swap out for a lithium battery and add another panel.

My question is what amp size controller I should install. I have a 30amp victron but a 20 amp would suffice. My question is do I risk any harm to my current setup going using the 30amp vs the right sized 20amp?

[powercat_ras]

Go with the Victron Smart Solar MPPT 100/30. it is rated to handle up to 440 watts of solar panels, it will do no harm to use less solar panels than that. It is easy to configure with a smart phone for LiFe battery when you are ready to change.

To add another solar panel it will need to have the right technical parameters and you will need to have the right wiring. You may need to increase the wire size from the controller to the battery, to handle 30 amps it will need to be 10 gauge copper minimum. It's probally not currently that large.

The sum of the two solar panels wattage would need to be 440 or less, if you are using the 100/30.

If you are adding another panel in series with the first one, then the next solar panel will need to be the same Vmppt and same Imppt as the current one (also means the same watts). This has the advantage of not increasing the wire size requirement from the roof to the controller solar panel input.

If you are adding another panel in parallel, then the next solar panel will need to be the same Vmppt but would not have to be exactly the same watts. You'll likely need a second 12 gauge copper wire run down to the controller from the second panel UNLESS the current wire run is 10 gauge copper (very unlikely).

[1woodward1]

Thanks, that is helpful info. That is the controller I have. I am going to try and install it this week. I will probably upgrade my battery before I add another panel. I read somewhere that to big of controller can hurt your battery. Over charging etc..

[creativepart]

Originally Posted by 1woodward1

I read somewhere that too big of controller can hurt your battery. Over charging etc..

Not sure where you found that info, but as powercat_ras said, there is really no issue overcharging.

Setting up the controller correctly is super easy with the Victron app.

I have a Victron 100/30 and it’s a very capable device. I upgraded my OEM Zamp PWM controller to the Victron. It’s a super simple process. One thing to be aware of is the Victron is an external device. It mounts flat on a wall externally with nothing behind it. All the wiring comes up to the device from the bottom.

Some other controllers sit proud of their mounting, covering an opening with wires and connections on the back side. Also some brands have visible display screens on their front. The Victron has no display screen as everything is done via the app.

I don’t know the controller or its layout in your TT. I think Winnebago is using SunPower controllers now? If it mounts on an interior wall with the wiring behind and a nice front cover and/or a display you’ll be replacing it with a large surface mount unit with all wiring exposed even if you just route the wires from behind the device through an existing opening.

The Zamp controller in my RV had all of those features,: wiring behind, LCD display, etc but was mounted in a basement compartment out of sight. So replacing it with the Victron was no issue at all. But I’ve seen others RVs that install the controller inside the RV in a prominent location on a main wall and when the Victron replaces the OEM controller it’s not the best look. Or, at least a very different interior esthetic.

[1woodward1]

I think I was worrying to much. My trailer came with a gpelectric gp-pwm-30a-sq controller and the converter is a WFCO 8955 with auto-detection. Thanks for everyone's help, I am going to try and install the new converter tonight. It should be easy. I am going to mount it right where the old controller was mounted.

[creativepart]

I’m confused. What does the Converter have to do with the Solar Charge Controller? These are two independent devices that have no correlation.

[1woodward1]

I went through the whole system this weekend to make sure the converter could support lithum batteries when I upgrade.

[Riverbend]

Just commenting in support of the Victron 100/30 MPPT controller. I swapped out my GoPower PWM for the Victron and saw a very noticeable improvement in solar gain.

[Marine359]

Victron Smart Solar 100/30 mppt is da bomb.
Don’t forget to put a 30 amp fuse between controller and battery. Also put a 30 amp manual reset breaker between array and charge controller. Without this, it’s a pita to disconnect the array.

[cclennon2]

Hello, when you replaced your PWM with the MPPT, did you have two negative and two positive wires attached to the PWM?

[Riverbend]

Originally Posted by cclennon2

Hello, when you replaced your PWM with the MPPT, did you have two negative and two positive wires attached to the PWM?

Possible on the "in" side, as lots of rigs come wired for plug-in auxiliary solar. My '23 View does, hence two P & N wires in, one P & N out to batteries.

[creativepart]

As Riverbend says, I also have two pairs on the PV side and one pair on the BAT side. On the PV side one pair goes to the solar port on the roof and the other pair goes to the external panel port, which in my motorhome is inside the rear driver’s side basement compartment.