Simple solar hookup

[KeithB]

For my 2108DS trailer; thinking of experimenting with a cheap solar setup. Probably purchase a 100W panel with controller. Question is what is the connection sequence? Panel to controller then to the exterior solar connection on the side of the trailer?

[creativepart]

It doesn't actually matter as long as you don't connect the panel directly to the battery.

Think of the panel combined with the controller the same as a regular battery charger that you'd plug into a wall outlet. I'd connect the controller to the battery, then plug in the panel to the controller - just like I'd connect an AC powered charger to the battery before plugging in to the wall outlet.

Remember, in full sun a panel will output close to 22v so, always be careful with the raw outputs from the panel.

[DavidM]

Not to be (too) argumentative, what is the problem with connecting a solar panel directly to a battery, particularly for just a few minutes? Just before you hook it up that way, the output of the panel will be at its Voc or about 22 volts as you note. When you hook it up to a battery it will immediately drop to the battery's resting voltage plus a few tenths due to the amps the solar panel is putting out.

The real risk is letting it sit for many hours, slowly driving up the battery's voltage until it starts "boiling" the electrolyte if it is a flooded cell lead acid battery or ruining it if it is an AGM. It will take quite a while, hours at least, for it to do that.

David

[creativepart]

Originally Posted by DavidM

The real risk is letting it sit for many hours, slowly driving up the battery's voltage until it starts "boiling" the electrolyte if it is a lead acid battery or ruining it if it is an AGM. It will take quite a while, hours at least, for it to do that.

Gee, David... you answered your own question. Thanks.

Presumably, if one connects a panel directly to the battery they are going to leave it there for a period of time. And, the result will be just as you said.

[Marine359]

If you wanna go cheap to experiment, just get a portable panel with built-in pwm controller. You can then connect directly to battery through a sidewall port, or just alligator clip it to the battery terminals. The problem will be that you won’t be able to move the panel very far from the battery due to voltage drop. A more elegant solution is to buy a portable panel with no built-in controller and connect it through the sidewall port to a mppt controller mounted near the battery. In this manner, the panel is sending higher voltage at lower amperage to the controller, thereby minimizing voltage drop. I can place my panel 30ft away from my camper with virtually no voltage drop and get the maximum charge voltage from the panel to the battery. This solution will cost about 50% more than the cheapy pwm approach.

[BobC]

Keith, just so I understand, are you considering a 100W portable panel as opposed to a roof mounted panel? And if it's a portable, will it be a purchased portable or a DIY portable using a standard 100W panel.

The reason I ask is that:

1. A roof-mounted panel wouldn't connect via the exterior solar connector. It would be hardwired to a controller which, in turn, would be hardwired to the batteries.

2.Some manufactured portable panels from a manufacturer have built in controllers so it's a one-step connection.

3. IMPORTANT: If you're going to use your exterior solar be very careful and determine the polarity of your external solar socket with a multimeter before you plug your panel/controller into it. You want to make sure you match positive to positive and negative to negative. Zamp sockets, which are commonly installed in RVs, have a polarity that is different from most non-Zamp portable panels and their connectors. Adapters are available if you don't want to re-wire your panel/controller's plug to match the socket:

https://www.solaroverstock.com/produ...everse-adapter

[KeithB]

Thanks for the replies all. Useful info. I am looking at a stand alone panel that I can fold up and put away. Definitely the economy route since we rarely boondock. But would like the option for an occasional night or two. I guess my main question is what the external solar connection on the trailer connects to? I assume straight to the battery. And if the controller is not part of the panel, where would I expect to mount it? These schematics are probably included with purchase??

[Marine359]

Hi Keith,
There are some un-addressed issues in your case, wherein it’s impossible to make recommendations without knowing for sure.

1. What kind of battery do you have?
2. Where is it currently mounted?
3. What is the model of your converter/charger?
4. If you already have a sidewall port, what is it connected to inside of the pass thru?
5. By stand alone, do you mean a panel with built-in charge controller?

Just a note: charge controllers are not waterproof, although some makers of panels with built-ins claim they are water resistant. Your charge controller will need to be protected from the elelements, and you need waterproof mc4 connectors, unless you’re running the wires directly to the battery.

[BobC]

Originally Posted by KeithB

Thanks for the replies all. Useful info. I am looking at a stand alone panel that I can fold up and put away. Definitely the economy route since we rarely boondock. But would like the option for an occasional night or two. I guess my main question is what the external solar connection on the trailer connects to? I assume straight to the battery. And if the controller is not part of the panel, where would I expect to mount it? These schematics are probably included with purchase??

1. I guess my main question is what the external solar connection on the trailer connects to? I assume straight to the battery.

I believe it's direct, possibly with an inline fuse. This is probably unlikely since Winnebago wouldn't have known how many watts you'd be connecting.

2. And if the controller is not part of the panel, where would I expect to mount it?

The ideal location is between the port and the battery in a protected location inside your TT. The following video shows a shot of the location of where Winnebago mounts the controller as part of their roof mount system. Ideally you may find the wire from the solar port is accessible so you can mount it in a similar location.

https://www.youtube.com/watch?v=q5CHep1J0Tk

It can also be mounted externally between the panel and the plug, but you'll need to take care to mount it in a weatherproof box. The following thread covers some of the same ground as your question:

https://www.winnieowners.com/forums/...ns-356837.html

3. Above all, don't forget my earlier caveat about the polarity of your solar port and your panel.

[KeithB]

Thanks for the additional info, and the video is great! As for more information, here you go. Thanks again for any additional feedback.

1. What kind of battery do you have?
WindyNation 100ah, AGM deep cycle

2. Where is it currently mounted?
The tongue of the trailer

3. What is the model of your converter/charger?
WFCO 8930

4. If you already have a sidewall port, what is it connected to inside of the pass thru?
Yes, have a sidewall port, but do not know what it connects to

5. By stand alone, do you mean a panel with built-in charge controller?
No, just mean the panel is not mounted on the trailer.

[Marine359]

OK, thanks for the info Keith. It adds lots of clarity.
I’m presuming the sidewall port is not connected to anything on the inside. This feature is often called “solar prep” by manufacturers.

The cheapest and most hassle free way for you to use portable solar would be to purchase a portable panel with a built-in charge controller. They’re pretty inexpensive. Since your battery is in the tongue, all you have to do is connect the panel to the battery terminals with alligator clips. Most of the panels with built-in controllers have a set of cables with alligator clip option. You won’t be able to run a very long cable. Try to keep it to 10ft or less. Easy peasy, you’re now charging your battery with solar.

You could spend more money by buying a panel with no controller, and the putting the controller next to the battery, but you’d then need a bigger battery box to accommodate the controller in a waterproof manner. The ideal way to use a mppt controller is to mount it in the pass thru and connect it to a sidewall port. But since your battery is outside, you’d the have to run a cable down through the floor and out to the tongue mounted battery.

Many, many people decide later that they would be better off upgrading to LiFePo4 batteries, and most MM owners mount them in the pass thru. Then it’s easy enough to connect up the inside mounted controller.

Since the ideal option (with possible battery upgrade) is not in your budget, search around Amazon for a portable panel kit that fits your budget and can be connected directly to your tongue mounted battery. You can always sell it later if you upgrade. A panel with pwm controller will not be as efficient as mppt, but it probably would meet your needs at this time.

[KeithB]

Great reply. Makes perfect sense. I’ve read on this forum before that the side wall connection is “useless”, which makes sense now. .Winnebago has provided the port then you have the flexibility to hook in to it to meet your needs. Thanks again!

[Marine359]

Originally Posted by KeithB

Great reply. Makes perfect sense. I’ve read on this forum before that the side wall connection is “useless”, which makes sense now. .Winnebago has provided the port then you have the flexibility to hook in to it to meet your needs. Thanks again!

When you hook up the sidewall port, it should look like this picture on the inside of the pass thru. Maybe not exactly, because my MM did not come with a port. I installed my own.

[BobC]

Originally Posted by KeithB

Great reply. Makes perfect sense. I’ve read on this forum before that the side wall connection is “useless”, which makes sense now. .Winnebago has provided the port then you have the flexibility to hook in to it to meet your needs. Thanks again!

I don't know what you mean by useless. If there's voltage present (easy multimeter check), it's connected to your battery and you might as well use it. If there's no voltage present, I'd think that it must be an easy hook up.

[Marine359]

Correct, but if you’re concerned about the connection, you can call customer service and give your VIN#. They will look up your build and tell you. As Bob indicated, if there’s voltage, it’s connected. If no voltage, customer service can give you the wire routing.

[KeithB]

Originally Posted by BobC

I don't know what you mean by useless. If there's voltage present (easy multimeter check), it's connected to your battery and you might as well use it. If there's no voltage present, I'd think that it must be an easy hook up.

I put a meter on the port connection and show voltage, 12.6 (not on shore power). Plan now is to run wire thru the port and mount controller in the pass through. There is a wire nut junction just inside the pass through.

[Shedboy]

Cheap & Easy Solar –



Harbor Freight Tools (HTF)


1. 1. “Thunderbolt” 25 Watt panel comes w multiple connectors and adapters including cigarette lighter adapter $89.


2. 2. “Thunderbolt” 100W Solar Charge Regulator” $19.99


Use it as a sun shield, set it on the RV dash board or in a window facing the sun, plug it into the dash cigarette lighter for engine battery, coach cigarette lighter for house battery.



Keeps the battery(ies) charged all winter, flooded cell needs fluid level maintained.

[BobC]

Originally Posted by Shedboy

Cheap & Easy Solar –



Harbor Freight Tools (HTF)


1. 1. “Thunderbolt” 25 Watt panel comes w multiple connectors and adapters including cigarette lighter adapter $89.


2. 2. “Thunderbolt” 100W Solar Charge Regulator” $19.99


Use it as a sun shield, set it on the RV dash board or in a window facing the sun, plug it into the dash cigarette lighter for engine battery, coach cigarette lighter for house battery.



Keeps the battery(ies) charged all winter, flooded cell needs fluid level maintained.

OK for keeping batteries charged in storage but way too small for what the OP wants to do.

[BobC]

Originally Posted by KeithB

I put a meter on the port connection and show voltage, 12.6 (not on shore power). Plan now is to run wire thru the port and mount controller in the pass through. There is a wire nut junction just inside the pass through.

This makes for a pretty easy install. If I understand you correctly, the controller will install in place of the wire nut connection.

And, again, don't forget to match the polarity of your panel to that of the port. Alternatively you could do this when you hook up the wires from the port to your controller. The downside of this is, if the wires from the port are color coded red/black, you're going be connecting black to positive at the controller which could be confusing to a future owner.

[splitley]

Check the polarity, could be reversed on the TT plug on side of TT.