Best weatherproof MPPT solar charge controller

[Bobbo]

I am about to buy 200 watts of portable solar panels in a suitcase configuration. I was about to get a Renogy 200 watt unit that comes with a weatherproof 20 amp PWM controller, but I really want an MPPT controller so I can hook those panels up in series rather than parallel. That way I can reduce voltage drop by carrying half of the amps at twice the voltage, and putting the controller beside the batteries instead of beside the panels. Then I had a brainstorm. Instead of buying the 200 watt unit with a PWM controller that I don't need, and wires I have to cut and reconfigure to get series panels, I will buy two of their 100 watt suitcases without a controller. That will make it easy-peasy to put them in series configuration. However, I still need a weatherproof MPPT controller.

Question, can someone point me to a decent weatherproof MPPT controller, preferably negative ground? (Victron doesn't list any of theirs as weatherproof.)

Thank you in advance

[Bobbo]

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.

[Bobbo]

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.

[CA_Traveler]

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.

[pauldub]

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.

[2oldman]

Where is your converter?

[FWC]

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.

[Bobbo]

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.

[2oldman]

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.

[CA_Traveler]

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.

[CA_Traveler]

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.

[Bobbo]

2oldman wrote:

Bobbo wrote:
Reason for weatherproof: set up suitcase panels with controller not in enclosed space and go sightseeing. It rains. Rain can happen when not expected.... put the solar controller close to the batteries rather than at the panels.

This still isn't making any sense to me. If the controller is close to batteries, wouldn't it be inside?

RANT ON
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. This is not rocket science. The controller will be out in the weather. The weatherproof box suggestion above is the only actual solution suggested. And it is a good one, probably the one I will use. Everyone else seems to be trying to explain why my problem can't exist.

Let me make this simple. A suitcase panel has a weatherproof PWM controller attached. I want to replace that PWM controller with a weatherproof MPPT controller. That is the complete, entire, problem. Where I am going to place that controller has gotten everyone sidetracked.

The reason I am going to place the controller near the batteries is explained below. According to a voltage drop calculator online:

Using 30 feet of 10g wire, a 200 watt (parallel) panel's PWM controller, on the panel, sends 14.4v and 12 amps out to the battery. You have 0.86v drop, so the battery gets 13.54v.

Using 30 feet of 10g wire, a 200 watt (series) panel sends 36v and 6 amps out to the MPPT controller at the battery box. You have 0.43v drop, so the MPPT controller sees 35.57v, and sends 14.4v to the battery, and the battery GETS 14.4v.

If I seem peeved, I am tired of reading that I need to put the controller inside. I can't. That is not a helpful suggestion.
RANT OFF

BTW, CA Traveler and agesilaus, you have been very helpful. Thank you.

[CA_Traveler]

Bobbo wrote:

CA Traveler wrote:
My 3 series panels on the roof have 62' total of 10 gauge wire to the controller resulting in 0.4% voltage drop which is very low. ie The panels on the ground could be about 31' from the controller.

You say your panels are SERIES. That is exactly what I am trying to accomplish. The weatherproof PWM controller that Renogy sells can not handle the panels in series, only in parallel. That is why I am wanting an MPPT controller.

And series panels with bypass diodes and a MPPT have better shade tolearance than than parallel panels. 12V panels may/may not have bypass diodes and 24V panels certainly will have bypass diodes. Disclaimer: This topic is often not understood.

[CA_Traveler]

Many trailers have outside batteries which is why I suggested a vented container.

[2oldman]

Bobbo wrote:
Reason for weatherproof: set up suitcase panels with controller not in enclosed space and go sightseeing. It rains. Rain can happen when not expected.... put the solar controller close to the batteries rather than at the panels.

This still isn't making any sense to me. If the controller is close to batteries, wouldn't it be inside?