While I value and respect many of the comments and opinions, provided on this thread, my own experiences and use debunk some of these comments and or theories.
I have been using both Solar and Generator, both daily for 2 years each, exclusively for the last 4 years. This includes the exclusive use of an Onan generator, running it at least 2 hours EVERY day for my first 2 years, on the road. Once I installed my first phase of Solar (600w), my generator use extended to about 2 to 6 hours use a month total. I used the Solar exclusively for the last 2 years, EVERY day.
My choice of this testing? Solar. But, I couch that by saying; "If you are only going out for a few days, or a vacation of a week or two, don't waste your limited funds on Solar, just get a higher AmpH battery/s and generator." Remember a generator can be used for so many issues, beyond a Truck Camper, as well at night, cloudy and snowy days.
If you are blessed with more money in your checking account than I have in mine, and most do, trip the trigger and install at least 100w of Solar with the option to expand. Smaller panels allow more flexibility of placement on the limited landscape on top of a TC. (Use Bigfoorford suggestion of cardboard cut out to the size of your planned solar panels to see how best they fit on your TC Roof) Plus the issues of tilting/snow load that can impact larger panels. If you are unsure on your need/demand, start out with 100w and keep adding another Panel after a year of use, until you meet the happy point where everything matches, sufficient amount of AmpH to operate the luxuries you wish and the amount of PV Watts to achieve Float S.O.C. in your batteries at least daily or within a 48 hr period.
While it is a pile of BS, running around and beating the drum to the song; "The sky is falling. The sky is Falling if you use 6V GC2 batteries and you WILL DIE!" There is a group that trully feel this way and I respect that and the fact that there is a bit of fact in that if you do lose one 6v GC2 battery the other is useless. True. With all the Drama? Not a chance. I think GPS have killed more people, lately, in remote areas than have a malfunctioning Camper battery. I can't think of a camper battery that impacts the starting and operating of an escape vehicle, like your truck, car or boots to the ground.
The first 2 years of fulltiming I started out using 2- 6v GC2 Eagle Batteries and 2- 12v Interstate Grp 27 batteries. At the end of that 2 years, when I switched to Solar, I was still using the 2- 6v GC2 Eagle Batteries and had gone through 7, thats right SEVEN 12v batteries. I switched out all of my 12v batteries (except the Ford Truck batteries) and no longer using them. Now 3 months into my 5th year of fulltiming, I am still using those original 2 - 6vGC2 Eagle Batteries, for my Phase II Solar Bank of batteries (3X100w Solar Panels) and I can't do anything to destroy these batteries, where the 12v batteries couldn't stay alive. At one point I thought they (the Eagle 6v batteries) were dead after discharging them to 10.8v and they came back. I think they like the topping off of the Solar, now, much better than the daily battery charging they once had for the first 2 .5 years of living with me.
Pick a battery type that best meets your needs, not what someone tells you, you HAVE to have. Location is an important issue and whether one battery will fit over another. The type of charging method is an important factor too, depending on 6v vs. 12v and your use.
No one has really brought up Flooded Wet Cell (FWC) over AGM type batteries. I like the AGM and also like the FWC, as I use both. Price ($) was the reason for my choice, as both types would last for about the same amount of time (Cycles), but the price was prohibitive for me. I use 10 batteries, spread between two battery banks and Solar Panel groups. The difference for me, was about $3,000 more for AGM after the initial cost of the FWC. The point for me here, to you, is that most batteries are destroyed by the owner, not by the batteries themselves (remember I killed 7 12v batteries). The biggest killer/longevity of batteries is discharging them below 55% of their S.O.C. Do this too many times and your can pretty much kiss your batteries good bye, after a couple of years. The big killer of Truck Camper batteries is the length of time that the campers sit, unused. During these periods, too often the batteries are not removed (cold can kill batteries) or not maintained (S.O.C.) while stored.
What battery do I recommend? Either. Follow my questions, above, to help make your decision. Me? I would, and will, keep using 6v batteries. Now if someone would GIVE me $4,000 I would switch to AGM batteries, over FWC batteries, as it was a price point for me, but they would still be 6v.
Generators? Excellent question. Don't buy your generator from the Factory!! Get the lines/electrical plumbed in, at the factory, but buy your generator from a Cummins/Onan dealer and have it installed, or do it yourself. Doing it this way you can save 25 to 30% over the cost of the option from most TC Manufacturers. As for Warranty, on Factory Installed Generators, the TC Manufacturers will send you to a Cummins/Onan Warranty repair service (at least Lance does) anyway. So having the Factory Installed option is useless when you have problems with the generator, which you will.
Which Generator to purchase? Good question. The opinions vary. Many of the top generators are the ones to go with(Red, Blue, Green). Being stuck with a broken generator is a big consideration, during a trip and the fact of how loud they are, is a consideration in how I make my choice.
I have an Onan Generator, installed from the Factory (Lance). It is convenient and it runs on Propane. All of these facts have been discussed. My exprerience is that the Onan is problematic. I have had two Onan Generators. The first one was replaced after 1900 hrs of daily use. The generator was rebult 4 times, before being replaced under warranty. The issue was Oil Blow by. Onan manufactured more than 2000 Onan 2500LP generators with a machining error in the head, allowing oil to drain through the engine and, ultimately, clogging the air filter. While Onan does not offer a recall, they have quietly replaced these problematic generators, when still under warranty. (That is how I know that the price of these generators are cheaper at the Cummins/Onan dealers, installed.) The second Onan Generator was installed and had only been in for warranty (when it would no longer start) due to a voltage regulator issue, spiking of voltage which damaged a few things inside my TC. They replaced the panel and it has been working fine, since, for almost another 1900 hrs of use. But that might be because I finally purchased a HONDA EU3000i Generator. The HONDA worked great the first 9 months I had it until I switched to Solar. After that it was only used on occasion. One day I was using the HONDA, when I was out on the motorcycle, to power my A/C in the Mojave Desert. When I returned, it was making a terrible racket. Something like a rock in a tin can. I turned it off and tried to look for the problem and didn't find it. When trying to restart it and it wouldn't start, elec start or rope pull (rope pulled out and would not retract).
Because I have redundancy on everything, (I won't die in the desert, even when people don't know where I am) the HONDA (I purchased it because everyone on the RV.net Forum told me that HONDAs were bullett proof), I continued on my adventure. I just pushed the HONDA off to the side and the Onan became my generator of use, when I needed one. The HONDA issue happened in early May. By November I came to a town where they serviced Inverter HONDA Generators and they fixed it under warranty. The problem? A bolt had dropped out of the manifold and dropped into the flywheel and sheared off the starter. The generator would run, you just couldn't get it started. In reviewing HONDA Generators issues, they have a continuing issue with bolts coming loose and dropping down into things and tearing things up. The biggest issue is one they have with a bolt falling into the cylinder and destroying the engine.
Conclusion? Not all Generators are created best, no matter what you hear, they all have problems. Pick one that best meets your needs and don't rely on it to save your life. Have a back up plan.
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08 F550-4X4-CC-6.4L Dsl-206"WB GVWR17,950#
09 Lance 1191
1,560wSolar~10-6vGC2-1,160AmpH~Tri-Star-Two(2)60/MPPT~Xantrex 2000W
300wSolar~2-6vAGM-300AmpH~Tri-Star45/MPPT~Xantrex 1500W
16 BMW R1200GSW Adventure
16 KTM 500 EXC
06 Honda CRF450X
09 Haulmark Trlr