2025 Grand Design Solitude 280RK vs 2024 Grand Design Momentum 399TH

Detailed Comparison

The 2025 Grand Design Solitude 280RK and 2024 Grand Design Momentum 399TH might look similar on paper, but dig into the details and you'll find meaningful differences.

In terms of footprint, the Grand Design Solitude 280RK stretches 34.5 ft while the Grand Design Momentum 399TH spans 28.0 ft. Weight-wise, the Grand Design Momentum 399TH is the lighter rig at 8,300 lbs versus 8,300 lbs.

For sleeping arrangements, the Grand Design Solitude 280RK offers room for 6 and the Grand Design Momentum 399TH can handle 9. The Grand Design Solitude 280RK benefits from 4 slide-out(s), expanding the interior when parked.

Looking at self-sufficiency, the Grand Design Solitude 280RK packs 57 gal of fresh water and 550W of solar. The Grand Design Momentum 399TH counters with 68 gal fresh water and 200W solar.

Price is often the deciding factor. The Grand Design Momentum 399TH starts at $61,000 MSRP, while the Grand Design Solitude 280RK commands $171,000 — a $110,000 gap. That's a significant 180% premium you'll need to justify.

Families with kids will appreciate the extra sleeping capacity and living space. Off-grid campers should pay close attention to solar wattage, battery capacity, and tank sizes. Full-timers should prioritize tank capacity, storage, and overall living comfort.

Both options have earned their place in the market. Your trip style and budget should be the final tiebreakers.