Well, let me start by saying that one would think this is an easy thing to deal with, but as it turns out it’s not quite that obvious. When we bought our new 2016 Tiffin Allegro RED we had it pre-wired for solar. We then asked the dealer to install some solar to just make use of the pre-wiring, nothing huge, keep the batteries topped off kind of thing. They decided to install a single 80 Watt panel and a basic 10 amp RDK controller. We picked up the unit, did our walk-through, drove it home and starting filling it back up.
Me being me, I decided to see if the solar was working, so I broke out a multi-meter and starting poking around. Come to find out as I was testing I was not getting any voltage to the controller from the panel. I found this strange at the least there should be something. I ordered a new basic controller, wired that, and same thing still nothing. At this point my head began to hurt wondering what the heck was wrong. I should mention the controller was mounted by the dealer in the battery compartment where the solar pre-wiring was located.
So next I climbed onto the roof, removed the cover to the wiring location and tested the panel up there on BOTH sides of the splice. That’s when I saw about 18 volts and DING! the bulb went off that something was really messed up. If you have ever visited the Tiffin factory you will learn that they are one of two coach manufacturers that custom labels every wire in a coach based on the model and floor plan. On inspection of the wires I found this:
- Roof – Labeled as Solar Panel
- Battery – Labeled as Solar Power
This told me the wire in the battery compartment was NOT the same wire as the roof as the dealer technician has also thought when he wired it. So where were the other ends of these two pairs?! There in lay the question that needed a phone call to Tiffin Service to find out. Come to find out these wires are stubbed out behind the cabinet over the driver’s head on the windshield. There is removable panel there and BINGO….two pairs of wires. Once this mystery was solved I verified the voltage on the panel side and order a THIRD controller, the same one tiffin uses the Go Power unit that supports up to 30 amps. I also re-routed the wires to the driver side window cabinet where the inverter control lived and mounted it there. I glued some extra 1/4″ plywood to the back of the thinner panel to make sure it was solid. I also made sure to put a 30 amp fuse on the hot side of the battery connection which the dealer never did so I could disconnect the controller if needed.
Hopefully this helps you if you also purchased a new Tiffin Allegro RED that is pre-wired for solar. I suspect any of the Tiffin units pre-wired are the same basic idea, but the inside locations of the hidden wires might be different. I have since added a matching 80 watt panel and plan to add two 130 watt panels in the future which will be close to maximum for the controller. It will actually be a little under which is also fine with me. The thing I also learned is based on the connections, this feeds the house batteries and you want to connect BEFORE the house disconnect. If you don’t then the controller will power off when the house disconnect is turned off and not do anything to keep the batteries topped off. Seems obvious, but the original installer connected to the other side so when sitting stored there would be no power to the controller to maintain battery charge unless the house disconnect was on….sort of silly if you do want to completely disconnect the unit and still keep the house batteries charging with no help from shore power.
Thanks for posting the info on Tiffin solar wiring. Much better than I got from my dealer and Tiffin.
If it helps a few people then it was worth documenting it! 🙂
The Allegra Open Road 36UA we bought this year was wired the same way. Fortunately I had asked before ordering the coach how they wired it. They put it there as most will use a smaller charge controller which will fit. I bought the Magnum MPPT charge controller which will work with multiple panels and interfaces well with the Magnum Inverter if you have that option.
I just bought a used 2016 Allegro Bus that has one 145W solar panel and GoPower 30 AMP Controller purchased as an option by the original owner. I had two 190W panels added. Since then I learned the current output of the Solar goes as high as 25-26 amps as measured by the controller. After a few days on a trip to Yosemite I discovered that a fuse blew out at the input from the solar panel to the controller and resulted in no charging to the batteries. This fuse is directly behind the controller. Also found another fuse at the Battery Buss Bars – Disconnect area. It is installed so that the batteries get charged even if disconnected from the RV loads. The problem is that Tiffin installed 25 AMP fuses when the GoPower is good for 30 AMP. Luckly the Yosemite Valley garage stocked fuses. I changed both fuses for 30 AMP and the Solar started working again.
But I noticed that the socket for the fuse is crimp wired to the Tiffin yellow wire. The socket pigtail (orange) leads are not of sufficient gauge to support even 25 AMPs, they get really hot compared to the Yellow wires (also whites). They should have use a socket with pigtails at 8 gauge or larger. There was 0.26 volt drop across the orange leads at the controller and 0.16 volts across the fuse pigtails at the battery leads. I will buy better fuse sockets and pigtails from Amazon and fix this issue. Since I am an Electronic Engineer, I always carry a multimeter with me for troubleshooting and am not afraid to figure things out when I’m on the road.
You check fuse leads easily by checking the fuse leads for heat at the battery end when the Solar is putting out maximum current. If the orange leads that connect to the Yellow Solar wire and +12Volt buss bar is hot – beware!!! The fuse leads behind the controller will be even hotter.