Best weatherproof MPPT solar charge controller

OK. Follow up.

I couldn't find what I considered an acceptable solution to the weatherproof charge controller question, so I decided to go a different route. I have had one 90w solar panel on the roof since I originally took delivery of the trailer. I decided to add a second 90 watt solar panel to try to increase charging.

To reduce voltage drop, I wanted to put the solar panels in series. The PWM controller that the Airstream dealer installed won't handle two panels in series, so I bought a Victron SmartSolar 100/30 to replace it.

I opened the trailer up to replace the controller only to find the dealer had mis-wired the system. He had wired the controller exactly as he should, BUT, this controller forces you to connect the PV negative wire to the battery negative. The dealer had hooked my PV negative wire to the battery POSITIVE. Both of the PV wires were hooked to the battery positive, giving a dead short. I was getting NO charge from the solar. No wonder I was unhappy.

Since I had the Victron, I went ahead and removed the dealer's PWM controller and installed the Victron. Correctly, this time.

I ordered the second solar panel before opening up the trailer. It is not here yet, but I will go ahead and install it. I will see how getting NO charging improves with 180w of solar, CORRECTLY installed, before I think about portable panels again.

My converter is halfway down the TT's length. Way too far to be of use.

The Victron was what I was lusting after, and may be the solution.

NRALIFR has given me another lead via pm that also looks very promising.

I need to decide between NRALIFR's suggestion and fabricating a vented weatherproof box for the Victron.

Thanks all.

FWC wrote:
The Victron MPPT 100/20 is the 'best' MPPT Charge controller for your application. It IP43 rated, so fine for spray and splashes, but I would still put it in some kind of enclosure. Maybe a small Pelican box so you can easily open the lid for ventilation when it is working hard.

Problem solved. As I posted install it in a vented box near the battery. 100V input voltage means you could have a 3rd panel later if desired. Need to check on the 290W spec. My controller is OK with overpaneling.

The controller isn't going to be 100% efficient and it will dissipate some amount of heat. You don't want to put it in a sealed box and cook it. 2oldman just gave a good hint. You can probably put it near the converter and have it indoors. I would try very hard to find a way to mount the controller indoors.

Where is your converter?

The Victron MPPT 100/20 is the 'best' MPPT Charge controller for your application. It IP43 rated, so fine for spray and splashes, but I would still put it in some kind of enclosure. Maybe a small Pelican box so you can easily open the lid for ventilation when it is working hard.

2oldman wrote:

Bobbo wrote:
No. My battery box sits on the tongue and has no space inside. My TT has no way for me to put the controller for a suitcase panel inside.

Thanks. That would have been good to know up front.

That was implied in the very first post when I said

Bobbo wrote:
However, I still need a weatherproof MPPT controller.

And many thanks to NRALIFER for the pm. It was VERY helpful.

Bobbo wrote:
No. My battery box sits on the tongue and has no space inside. My TT has no way for me to put the controller for a suitcase panel inside.

Thanks. That would have been good to know up front.

Something to consider - It's a good practice to estimate your current power consumption. Many later find they want more so future upgading is something to consider - ie wiring to support, etc.

You've done a good job of clarifying your requirements, I can't recall a thread that doesn't get off track.

The MPPT controller input vultage MUST be greater than the combined panels Voc (open circuit) voltage plus panel voltage temperature variations to protect the electonics. The typical 12V panel Voc is about 21V, so make sure the MPPT controller inut is about 42V + 10V for low tempeatures. This is not the charging voltage.

Vmp (maximum power) is the panel charging voltage about 18V for a 12V panel. So the panel output is 2*Vmp at Isc (short circuit which is usuall be best spec for amps).

Now subtract the panel to controller wiring voltage loss. Subract about 5% loss for the MPPT controller, convert the resulting power to amps at 14.4V for the battery. With the controller near the battery you can ignore that wiring loss.