The thread OP is from/living in the Midwest where solar is very iffy at best and there's trees everywhere too which virtually block out the sun's rays anyway. Note that the promotors of solar are from the desert/bleak/virtually treeless areas of North America. We know the difference as that's where we live in the Midwest also and very smartly opted for dual alternators on our ordered diesel truck and been so happy we did.
Remember that the alternator works equally fast in recharging in any area/location you might be in unlike with iffy solar. Alternators are not affected by cold, altitude, clouds or trees, rain or snow, and is very fast and dependable.
It's not only the fact that the dual alternators will quickly when at engine idle recharge all the batteries (2 in the truck and 3 group 31 batteries for the Lance TC with its 1500 watt inverter or our Carriage 5th wheel with 5 same batteries in it and 2 more in the bed of the truck for powering the 5th wheel with its 2500 watt inverter). Even if in direct sun for 12 ours a day everyday, solar would be about like using a candle to heat a home in zero degree weather. Basically useless!
The additional plus is that having dual alternators and buying the extra serpentine single alternator belt stored under the seat means even if an alternator fails, you simply change belts and are good to go with the other alternator. A real game changer!
$400 seems a very high price for a second alternator as ours was well less than half of that cost.
