When I initially built out my van last summer, I left out solar for the sake of simplicity. Now, 40,000 miles later, I don’t see a reason for ever adding solar. I’d rather use my roof space for an AC unit and a couple of MaxxAir fans. My use case: I have somewhat high power needs (fridge, convection microwave, induction cooktop). I am always in urban, suburban, or rural/small towns. I am rarely in places where it would be acceptable to lay out solar panels. I am frequently in areas where it is convenient enough to grab my power station and charge it inside (ie. gym, restaurant, visitor center, hospital).
If you do the research, you’ll discover the general consensus is that EcoFlow makes some the best power stations on the market. If you are willing to accept its biggest shortcoming: battery chemistry. The lifecycles from EcoFlow power stations (except the Delta Pro) makes it expensive relative to its closest rival, Bluetti. I don't know of any good reason for choosing a Jackery or GoalZero.
I bought a Delta 1300 shortly after it was launched (the models currently available have significant enhancements over mine). I was attracted to its portability (light weight and integrated power supply), user interface, and super fast charging. The latter is what makes solar unnecessary. With a rate of 1000W per hour when connected to a wall outlet, it took 30 minutes to restore all the power I used in a day. Actually, it usually took less than that because I kept it plugged into the cigarette port when driving, charging at 100W per hour.
Recently, after watching a YT video by Gaye N Robert, I modified my setup, eliminating the need to remove the Delta from my vehicle to charge it. I connected an inverter directly to my chassis battery. I now charge my Delta at 1000W per hour while driving, by plugging it into the inverter.
The ability to do this without frying the alternator is obviously vehicle dependent. A lot of vans have high output alternators. The Transit has a 250A alternator, and OEM dual alternators can be ordered; diesel Sprinters have a 220A and several aftermarket secondary alternator options. But without a massive battery bank, dual alternators are overkill. My vehicle has a single alternator, I haven't noticed any strain (noise or rpm) on the engine while running the inverter, though it is only used as needed, it is not on continuously.
The EcoFlow Deltas at max charging may exceed the capabilities of some vehicles, but they can be dialed down via the app as needed. Most power stations are not that demanding. The Bluetti EB70S has a max charging speed of 200W per hour which means it would take more than 3 hours to fully recharge. So long as the battery capacity is sufficient to meet stationary days, this shouldn't be a problem. My Delta is large enough to last 2-3 days before its depleted, since I rarely go more than 2 days without driving, keeping it charged is not a problem. It would take a little more than 1 hour of driving to go from 0-100%, but to date, that hasn’t been necessary.
I think the usefulness of solar is a function of how the vehicle is used. Folks who are stationary camping on BLM land in the sunny southwest for weeks at a time may get a lot of utility from solar. Urban dwellers, foul weather campers, and highly mobile travelers, may be well served by selecting a fast charging power station and using their engine like a generator. If idling a vehicle for 20 minutes can store as much power as 6 hours of full sun, then solar isn’t very compelling.
