Solar Inverter Sizing & Selection Guide (2026) | PES Supply
Solar Inverter Sizing & Selection Guide (2026)
Complete guide to choosing the right inverter for your solar system
Types of Solar Inverters
| Type | Best For | Cost | Efficiency | Monitoring |
|---|---|---|---|---|
| String Inverter | Unshaded roofs | $1,000-$3,000 | 97-99% | System-level |
| String Inverter + Optimizers | Partial shade | $1,500-$4,000 | 97-99% | Module-level |
| Microinverter | Complex roofs, shade | $1,200-$2,500 | 96-97% | Module-level |
| Hybrid Inverter | Solar + battery | $2,000-$5,000 | 96-98% | System-level |
| Off-Grid Inverter | Off-grid systems | $1,500-$5,000 | 90-95% | System-level |
Sizing Your Inverter
The inverter must handle both the DC input from panels and the AC output to your home:
Rule of Thumb: Inverter AC rating = 75-100% of array DC rating
Example: 10 kW array → 7.5-10 kW inverter (oversizing = clipping at peak)
Inverter Sizing by System Size
| Array Size | Panel Count (450W) | Min Inverter | Recommended Inverter | Est. Cost |
|---|---|---|---|---|
| 3 kW | 7 panels | 2.5 kW | Enphase IQ8+ (7 units) | $1,400 |
| 5 kW | 12 panels | 4.0 kW | SolarEdge SE5000H | $1,500 |
| 7.5 kW | 17 panels | 6.0 kW | EG4 6500EX | $3,500 |
| 10 kW | 23 panels | 8.0 kW | SolarEdge SE10000H | $2,500 |
| 15 kW | 34 panels | 12.0 kW | SMA Sunny Boy 12.0 | $3,000 |
| 20 kW | 45 panels | 15.0 kW | 2× SolarEdge SE10000H | $4,500 |
Max DC/AC Ratio (Oversizing)
Inverter manufacturers specify a maximum DC-to-AC ratio:
| Manufacturer | Max DC/AC Ratio | Notes |
|---|---|---|
| SolarEdge | 1.35 (some 1.55) | Clipping above ratio |
| Enphase IQ8 | 1.33 | Module-level, no clipping issue |
| SMA Sunny Boy | 1.30 | SMA ShadeFix |
| EG4 | 1.50 | Off-grid/hybrid |
| Sol-Ark | 1.50 | Hybrid |
Grid-Tie vs Off-Grid vs Hybrid
| Feature | Grid-Tie | Off-Grid | Hybrid |
|---|---|---|---|
| Grid Connection | Required | Not needed | Optional |
| Battery | No | Required | Optional |
| Backup Power | No (shuts off) | Yes | Yes |
| Net Metering | Yes | No | Yes |
| Best For | Max savings | Remote locations | Backup + savings |
Popular Inverters at PES Supply
| Inverter | Type | Power | Key Features |
|---|---|---|---|
| EG4 6500EX | Hybrid | 6.5 kW | 48V, 2 MPPT, split-phase |
| EG4 3000EHV | Off-Grid | 3.0 kW | 48V, 1 MPPT, stackable |
| Sol-Ark 15K | Hybrid | 15.0 kW | 3-phase, 6 MPPT |
| SolarEdge SE10000H | Grid-Tie | 10.0 kW | HD-Wave, optimizer ready |
| SMA SB 12.0 | Grid-Tie | 12.0 kW | Sunny Boy, Secure Power Supply |
| Enphase IQ8+ | Microinverter | 300W/panel | Per-panel, grid-forming |
| Sungrow SG4400UD | Commercial | 4.4 kW | 3-phase, hybrid-ready |