5 MW PV Grid Interconnection Cost Breakdown (Q3 2026 China Supplier Pricing)
5 MW PV Grid Interconnection Cost Breakdown (Q3 2026 China Supplier Pricing) — itemized bill of materials and FOB pricing for a typical configuration.
Estimated total (FOB): $1,607,744
Bill of materials
| Item | Specification | Qty | Price (USD) |
|---|---|---|---|
| PV Modules (550 Wp Mono PERC) | 550 Wp · 10455 pcs (DC/AC ≈ 1.15) | 10455 | $632,528 |
| Central Inverter (2.5 MW string/central) | utility-scale · 5.0 MW AC | 2 | $500,000 |
| Ground Mounting Structure (Fixed tilt) | tilt optimized for lat 30° | 1 | $400,000 |
| Box-Type Substation (step-up) (0.8/10 kV) | 1600 kVA step-up | 4 | $67,600 |
| HV Switchgear (collector) (KYN28A-12) | collector switchgear · 1 feeders | 1 | $2,226 |
| Ring Main Unit (XGN15-12) | SF6 · 630 A · 4-way | 1 | $2,350 |
| SVG (Static Var Generator) (SVG-1Mvar/10kV) | dynamic reactive compensation | 1 | POA |
| Collector Cable (YJV 26/10 kV) | 240 mm² · radial feeders · 1 feeders | 1 | POA |
| Earthing System (flat bar + rods) | plant grounding grid | 1 | $1,040 |
| SCADA Monitoring (plant-level) | power plant controller + SCADA | 1 | $2,000 |
Single-line diagram
How it was calculated
- ['Voltage level (Module A)', '5.0 MW → 10 kV POI (0.8 kV (inverter) → 10 kV (collector) → 10 kV POI)']
- ['Collector (Module B)', '4 arrays × 1600 kVA box sub · 1 feeder(s) · 240 mm² cable']
- ['Main transformer (Module C)', 'none (collector connects directly to POI)']
- ['Reactive power (Module D2)', 'requirement ±0.75 Mvar → SVG 1 Mvar']
- ['Short-circuit (Module D4)', 'grid 28.87 kA + PV 0.35 kA (current-source) = 29.21 kA at 10 kV POI']
- ['Generation (Module F)', 'GHI 3.97 kWh/m²/day · PR 0.8 → P50 5,796,200 kWh/yr']
- ['Probability (Module F)', 'P75 5,639,934 · P90 5,499,435 kWh/yr (σ=4% interannual)']
- ['LCOE (Module G)', '$0.1063/kWh full-cost (O&M + WACC + inverter replacement + degradation)']
- ['Economics (Module G)', 'payback 23.8 yr · IRR -0.5% · NPV $-3,347,159 · DSCR 0.47']
What drives the cost
- Equipment — the transformer/switchgear/inverter is the largest single line item.
- Storage (where applicable) — batteries are the biggest swing factor.
- Copper & freight — copper-linked cabling and freight shift landed cost ±5–10%.
Frequently asked questions
At what voltage should a PV plant connect to the grid?
Connection voltage follows plant size: under ~250 kW use 0.4 kV, 250 kW-6 MW use 10 kV, and above 6 MW use 35 kV or 110 kV. A 50 MW plant typically connects at 110 kV. The choice balances transformer losses against interconnection cost; grid operators specify the exact point of connection. The calculator selects voltage and main-transformer rating automatically.
How much reactive compensation does a PV plant need?
Grid codes (GB/T 19964, IEEE 1547) require PV inverters to operate within a 0.95 leading to 0.95 lagging power-factor range and often to supply reactive support during faults. Large plants usually add a centralized SVG/SVC of 10-30% of plant capacity. A 50 MW plant commonly pairs a 10-15 Mvar dynamic compensator to meet grid-code voltage support.
What short-circuit contribution does a PV inverter add?
A grid-following PV inverter contributes roughly 1.0-1.2 times its rated current for a few cycles, far less than a synchronous generator (5-7 times rated). For a 50 MW plant the contribution is ~60-70 MVA. This matters when checking breaker and transformer fault ratings; the calculator folds PV short-circuit contribution into the interconnection study.
What is the typical collector system voltage in a PV plant?
Large PV plants gather strings through 800 V DC to central or string inverters, then step up through a 0.8 kV to 10 kV or 35 kV collector network. String inverters (up to 250 kW) feed a 10 kV collector; central inverters (500 kW-3 MW) feed 35 kV. Collector cable runs are typically 5-20 km, sized for under 2% voltage drop.
How is the main transformer sized for a PV plant?
The main transformer rating matches inverter AC capacity divided by power factor, with 5-10% margin and the next standard size (IEC 60076). A 50 MWac plant with 0.95 pf needs roughly 55 MVA, so select 63 MVA. Most PV main transformers are oil-immersed, ONAN, 35/110 kV, with a no-load loss limit set by GB/T 6451 efficiency grades.
What grid-code compliance checks does interconnection require?
Key checks per GB/T 19963/19964 and IEEE 1547 include: low/high-voltage ride-through, frequency ride-through (typically 47.5-51.5 Hz), power-factor capability, ramp-rate limits, and anti-islanding. The calculator verifies voltage-level fit, main-transformer sizing, reactive compensation and fault contribution, flagging parameters that fall outside the typical grid-code envelope.
Size your own configuration
Run the calculator for your exact load and get a full BOM + FOB price.
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