If you own a 2006-or-newer Winnebago motorhome, there is a good chance it left the factory with a Zamp Solar sidewall port: the small weatherproof plug on the outside of the coach where you connect a portable solar panel. What most owners don't know is that Winnebago wired that port differently from most other RVs, and it changes which portable panel you should plug into it.
The short version: on these coaches, the port is wired to a solar charge controller that is already installed in the motorhome. That means you want an unregulated portable panel, one without its own controller. Here is why, how to check your coach, and the panel we built for it.
Regulated vs. unregulated: what the difference is
A solar panel on its own puts out a voltage that is well above what a 12V battery wants. A 45W panel like ours has an open-circuit voltage of about 24V. Something has to stand between the panel and the battery to hold that down to safe charging levels and walk the battery through bulk, absorption and float. That something is the charge controller.
- A regulated panel has the charge controller built in or attached to the panel or its case. What comes out of the cable is already controlled and safe to send to a battery.
- An unregulated panel has no controller. What comes out of the cable is raw panel output, and it must go through a charge controller before it reaches a battery.
Neither is better. They are built for two different kinds of wiring, and the right one depends entirely on what is behind the port on your RV.
How most RVs wire the sidewall port
On most travel trailers, fifth wheels and motorhomes with a portable solar port, the port runs straight to the battery. There is no controller in the coach for that port, so the panel has to bring its own. That is why most portable kits, including our DuraLite portable kits, ship with a charge controller in the case. Plug an unregulated panel into a port like that and you are putting raw panel voltage directly on the battery, which can overcharge and damage it.
How 2006+ Winnebago motorhomes do it differently
Many Winnebago motorhomes from 2006 onward came with the Zamp Solar sidewall port wired to a charge controller installed inside the coach, not directly to the battery. The controller is already there, doing the regulating.
That is why a regulated panel is the wrong choice on these coaches. Plug a panel with its own controller into a port that already feeds a controller, and you end up with two controllers in series. They are not designed to work that way: the coach's controller sees regulated, fluctuating input instead of panel voltage, its charging stages and the panel's charging stages work against each other, and charging becomes slow or unreliable. On these Winnebagos, the panel should simply supply power and let the coach's controller do its job.
How to check your coach before you buy
Model year is a strong hint but not proof. Coaches get modified, options vary and owners rewire things. Before you buy any portable panel, confirm what is behind your port:
- Find the charge controller. Look for a solar charge controller inside the coach. Your owner's manual or the Winnebago solar documentation for your model will show whether one was installed and where. If you find a controller with a solar input wired from the sidewall port, you have the setup this panel is built for.
- Check the port. These coaches use the Zamp Solar Ready sidewall connection. If your port looks different or has been replaced, confirm the connector before ordering.
- Check the controller's limits. Make sure the controller's maximum solar input voltage and current are above what the panel puts out (24.35V open circuit, 2.37A). Any controller sized for a typical RV solar setup will be well above that.
- If there is no controller, your port goes direct to the battery. Use a regulated portable kit instead. Our RV solar port guide walks through the common port types.
Never connect an unregulated panel directly to a battery. If you are not sure what your port is wired to, ask your Winnebago dealer or contact our support team before plugging anything in.
The panel we built for it: OBSIDIAN® Series 45W Portable Kit for Winnebago
We built the OBSIDIAN® Series 45W Portable Solar Kit for Winnebago Motorhomes specifically for these coaches. It is an unregulated kit, so it plugs into your Zamp sidewall port and hands charging over to the controller already in your motorhome.
- 45W OBSIDIAN® panel, 2.37A listed output, 24.35V open circuit, with a 25-year output warranty.
- Integrated carry case that becomes an adjustable stand. Set it out at camp, angle it toward the sun, pack it away to travel.
- Low profile for storage: 32 × 15.5 × 2 inches and 12.5 lb, with an anodized aluminum handle and a padded pocket for the cables.
- Everything to connect: a 15-foot ATP-to-ATP extension cable, plus 6-inch ATP-to-SB50 and SB50-to-SAE adapters.
What 45 watts does for you
A 45W panel is a battery maintainer and top-up, not a whole-house power source. On a typical sunny day, angled toward the sun, expect roughly 10 to 12 amp-hours back into a 12V battery. That is enough to:
- offset the parasitic draws that slowly drain a parked motorhome (propane detector, radio memory, stereo, control boards),
- keep batteries topped up during a long stay at camp with light use, and
- recover some of an overnight draw from lights, the water pump and phone charging.
It will not keep up with a residential fridge, a furnace running all night or heavy inverter use on its own. Actual output depends on sunlight, panel angle, shading, battery condition and what you are running.
The bottom line
If your 2006+ Winnebago has a Zamp sidewall port wired to a charge controller in the coach, you want an unregulated panel, and the OBSIDIAN® 45W Portable Kit for Winnebago was built for exactly that setup. If your port goes straight to the battery, choose a regulated kit instead. Confirm your wiring first, and when in doubt, ask us.