OutBack VFXR3648A
For a cabin or off-grid home built around 120 V loads, with room to stack a second unit later. Rugged and code-friendly, but it idles high for its size.
Amazon $2,139$2,139
The OutBack VFXR3648A rates 3.8 among 120V inverter-chargers 48V inverters; the OutBack Radian GS4048A rates 3.7 among split-phase inverter-chargers ones. The OutBack VFXR3648A costs $856.75 less ($2,139 vs $2,995.75).
OutBack Radian GS4048A
For a small off-grid home that needs 240 V for a well pump but only 4 kW of steady load. Hard to find now, so check stock before designing around it.
Solar Cellz USA $2,995.75$2,995.75
Prices were last checked October 24, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Scores side by side
These two sit in different size classes (120V inverter-chargers and split-phase inverter-chargers), and each is scored against the reference points for its own class, so a rating says how well each does among its own size peers. How we rank explains each factor.
| Factor weight | OutBack VFXR3648A | OutBack Radian GS4048A |
|---|---|---|
| Overall rating | 3.8/5 | 3.7/5 |
| Value 30% | 32 $0.59 per continuous watt | 0 $0.75 per continuous watt |
| Idle draw 15% | 66 34 W idle with nothing plugged in | 95 34 W idle with nothing plugged in |
| Safety listing 15% | 100 ETL listed to UL 1741 (2nd Ed. with supplement SA) | 100 ETL listed to UL 1741 (2nd Ed. with supplement SA) and CSA C22.2 No. 107.1 |
| Warranty 15% | 100 5-year warranty | 100 5-year warranty |
| Features 15% | 50 optional remote, app add-on, lithium charge profile, hardwire terminal | 70 optional remote, app add-on, lithium charge profile, 120/240 V split-phase, hardwire terminal |
| Efficiency 10% | 89 93% peak efficiency (maker rating) | 89 93% peak efficiency (maker rating) |
Specifications
| OutBack VFXR3648A | OutBack Radian GS4048A | |
|---|---|---|
| Output | ||
| Type | Pure sine wave inverter-charger | Pure sine wave inverter-charger |
| AC output | 120 V | 120/240 V split-phase |
| Continuous power | 3,600 W | 4,000 W |
| Surge power | 5,400 W for 5 s | 6,000 W for 5 s |
| DC input range | 42 to 68 V | 40 to 64 V |
| Idle draw | 34 W (0.7 A at 48 V) | 34 W (0.7 A at 48 V) |
| Power-saving draw | 9 W | 10 W |
| Peak efficiency | 93% | 93% |
| Connections | ||
| AC outlets | 0 | 0 |
| GFCI outlets | No | No |
| Hardwire terminal | Yes | Yes |
| USB ports | None | None |
| Transfer switch | Yes | Yes |
| Pass-through rating | 60 A | 50 A |
| Charger | 45 A | 57.5 A |
| Lithium charge profile | Yes | Yes |
| Parallel units | Yes | Yes |
| Control and build | ||
| Remote | Optional extra | Optional extra |
| App | Optional add-on | Optional add-on |
| Display | No | No |
| Safety listing | ETL listed to UL 1741 (2nd Ed. with supplement SA) | ETL listed to UL 1741 (2nd Ed. with supplement SA) and CSA C22.2 No. 107.1 |
| Design | Low-frequency (transformer) | Low-frequency (transformer) |
| Cooling | fan | fan |
| Dimensions | 12 x 8.25 x 16.25 in (30 x 21 x 41 cm) | 28 x 16 x 8.75 in (71.1 x 40.6 x 22.2 cm) |
| Weight | 61 lb | 82 lb |
| Warranty | 5 years | 5 years |
| Released | - | 2013-11 |