Sungrow SG5.0RT vs Fronius Primo 3.8-1
The Sungrow SG5.0RT edges ahead in this string-vs-string matchup. It delivers higher efficiency (97.7% vs 96% CEC). For most installations in this power range, the Sungrow SG5.0RT is the stronger choice.
Key Differences
- • Sungrow SG5.0RT delivers 5.0 kW AC output while Fronius Primo 3.8-1 delivers 3.8 kW, a 1200W difference.
- • Sungrow SG5.0RT achieves 97.7% CEC efficiency vs 96%.
- • Both carry 10-year warranties.
Specifications Breakdown
Power Output & Efficiency
The Sungrow SG5.0RT delivers 5.0 kW AC output at 97.7% CEC efficiency (98.5% peak), while the Fronius Primo 3.8-1 delivers 3.8 kW at 96% CEC (96.6% peak). The 1200W power difference determines the maximum solar array each inverter can handle. The Sungrow SG5.0RT's higher CEC efficiency means it converts 1.7 percentage points more DC solar energy into usable AC electricity. On an average 8 kW system producing 12,000 kWh annually, this efficiency gap translates to approximately 204 kWh more usable energy per year, worth roughly $31 at $0.15/kWh.
MPPT Trackers & Panel Configuration
The Sungrow SG5.0RT features 2 MPPT inputs while the Fronius Primo 3.8-1 has 2. Matched MPPT counts provide equal flexibility for panel string configuration. Both can independently optimize 2 separate panel groups. The Sungrow SG5.0RT accepts up to 600V DC input with a 80-600V operating range, versus 600V DC and 80-600V for the Fronius Primo 3.8-1.
Monitoring & Communication
The Sungrow SG5.0RT includes Sungrow iSolarCloud (WiFi/Ethernet) monitoring with WiFi / Ethernet / RS-485 communication, while the Fronius Primo 3.8-1 offers Fronius Solar.web (WiFi/Ethernet) via WiFi / Ethernet / USB / Fronius Solar API. Different monitoring ecosystems mean different mobile app experiences, data granularity, and integration options with third-party energy management systems. Reliable monitoring is essential for detecting production drops, identifying panel-level issues, and maximizing system uptime over the inverter's lifetime. Both carry IP65 protection ratings for equivalent environmental durability.
Warranty & Reliability
The Sungrow SG5.0RT comes with a 10-year warranty while the Fronius Primo 3.8-1 offers 10 years. Matched warranty durations mean equal long-term manufacturer protection. Consider budgeting for a potential inverter replacement during the 25-30 year lifespan of your solar panels.
Specification Comparison
| Specification | Sungrow SG5.0RT | Fronius Primo 3.8-1 |
|---|---|---|
| Type | string | string |
| AC Power | 5000W | 3800W |
| Peak Efficiency | 98.5% | 96.6% |
| CEC Efficiency | 97.7% | 96% |
| MPPT Trackers | 2 | 2 |
| Monitoring | Sungrow iSolarCloud (WiFi/Ethernet) | Fronius Solar.web (WiFi/Ethernet) |
| Weight | 10.5 kg | 21.5 kg |
| Warranty | 10 years | 10 years |
5-Dimension Head-to-Head Analysis
1. Power Capacity
Winner: Sungrow SG5.0RTThe Sungrow SG5.0RT delivers 5.0 kW versus 3.8 kW. The capacity difference is modest but may matter for systems near the power limit.
2. Conversion Efficiency
Winner: Sungrow SG5.0RTThe Sungrow SG5.0RT achieves 97.7% CEC efficiency versus 96%. Every percentage point of efficiency translates to approximately $100-200 in additional energy production over a 25-year system life on an average 8 kW system. This efficiency gap is substantial and meaningfully impacts lifetime ROI.
3. Features & Architecture
Winner: TieBoth are strings with 2 MPPT trackers. Matched MPPT counts mean equal roof configuration flexibility.
4. Warranty & Reliability
Winner: TieBoth carry 10-year warranties — equal long-term protection.
5. Overall Value
Winner: Sungrow SG5.0RTWeighing efficiency, warranty, and power capacity together, the Sungrow SG5.0RT delivers the better overall package. Get installer quotes for both to compare actual installed costs in your area.
Sungrow SG5.0RT
The Sungrow SG5.0RT is an ultra-compact 5 kW residential string inverter from the world's largest inverter manufacturer, featuring 98.5% peak efficiency and one of the lightest form factors in its class.
Pros
- + 98.5% peak efficiency leads the 5 kW residential string inverter class
- + At 10.5 kg, it is one of the lightest 5 kW inverters available for easy single-person mounting
- + Sungrow is the world's largest inverter manufacturer by shipment volume, ensuring supply chain stability
- + iSolarCloud app provides comprehensive monitoring and energy analytics
Cons
- - US market presence and installer support is still developing compared to domestic brands
- - 10-year warranty is shorter than microinverter alternatives though extended warranties are available
Fronius Primo 3.8-1
The Fronius Primo 3.8-1 is the entry-level SnapINverter for small US residential systems, featuring dual MPPT, wide 80-600V DC range, and Fronius's signature Austrian build quality. Predecessor to the GEN24 series.
Pros
- + Dual MPPT handles two roof orientations independently
- + Wide 80-600V voltage range — SuperFlex design for flexible string sizing
- + SnapINverter mounting for quick disconnect and service
- + IP65 outdoor rated with -40°C cold start capability
- + WiFi and Ethernet monitoring built-in
Cons
- - No battery integration — pure string inverter only
- - 96.0% CEC efficiency lower than newer HD-Wave and GEN24 platforms
- - 10-year warranty shorter than Enphase 25-year
- - Discontinued model — replacement parts availability declining
Choose Sungrow SG5.0RT If...
- ✓ You want maximum energy conversion efficiency to minimize power losses
- ✓ Your system size requires 5 kW+ of inverter capacity
- ✓ Residential installations that prioritize peak efficiency and lightweight design in a proven string inverter from the global market leader
Choose Fronius Primo 3.8-1 If...
- ✓ Small residential systems of 3-4 kW on homes with two roof orientations needing independent MPPT tracking.
Our Recommendation
We recommend the Sungrow SG5.0RT for most buyers in this comparison. It wins 3 of 5 key dimensions and offers a clear advantage in the metrics that matter most for a inverter purchase. The Fronius Primo 3.8-1 remains a good product, but the Sungrow SG5.0RT delivers better overall value for the majority of installations.
Frequently Asked Questions
Which is better, Sungrow SG5.0RT or Fronius Primo 3.8-1?
The Sungrow SG5.0RT edges ahead in this string-vs-string matchup. It delivers higher efficiency (97.7% vs 96% CEC). For most installations in this power range, the Sungrow SG5.0RT is the stronger choice.
Which inverter is more efficient?
The Sungrow SG5.0RT achieves 97.7% CEC efficiency (98.5% peak) versus the Fronius Primo 3.8-1 at 96% CEC (96.6% peak). Sungrow SG5.0RT converts more DC solar power to usable AC electricity. CEC efficiency is the more realistic measure, accounting for varying power levels throughout the day.
Can Sungrow SG5.0RT or Fronius Primo 3.8-1 work with battery storage?
The Sungrow SG5.0RT is a string without built-in battery management. The Fronius Primo 3.8-1 is a string without built-in battery management. Both require an AC-coupled battery system (like Tesla Powerwall) for storage, or replacement with a hybrid inverter.
Which has a better warranty?
The Sungrow SG5.0RT offers 10 years versus 10 years for the Fronius Primo 3.8-1. Both offer identical warranty terms. Paid warranty extensions are typically available from both manufacturers.
Which inverter type is better: string or string?
Both are strings, so the comparison comes down to specifications, brand ecosystem, and pricing rather than architecture. Compare efficiency, warranty, monitoring quality, and installer support when choosing between these two strings.
Related Resources
Last updated: February 2026