800 kW Rooftop PV: 0.4 kV Grid Connection with Anti-Islanding & Metering Deep-Read
800 kWp PV · 0.4 kV grid connection · anti-islanding · net metering · 640 kW effective
1 · TL;DR Conclusion
Conclusion: this 800 kW rooftop PV connects at 0.4 kV with 800 kWp of PV (640 kW effective, 100% renewable), anti-islanding + net metering — configurator total ≈ $230,007, EPC ≈ $440,000, 6 yr payback, 18.15% IRR, 345% 25-yr ROI, 487 t CO2 avoided/yr (feasibility-level).
- •0.4 kV LV grid connection; 800 kWp PV → 640 kW effective demand, stdKva 674, 100% renewable share
- •PV yields ≈812,160 kWh/yr (P50), 0.8 self-consumption → 649,728 kWh self-used + 162,432 kWh exported (net metering)
- •Anti-islanding + net metering on the 0.4 kV PCC; compliance pass (no failures)
- •Economics: $440,000 EPC, 6 yr payback, 18.15% IRR, 345% ROI, LCOE $0.0562/kWh, NPV $412,017
- •Watch V6 (THDi over limit → APF/SVG) and V7 (160 kW over-generation → export or storage)
2 · Solution Overview
A rooftop distributed PV plant at 800 kW is sized to the 0.4 kV grid connection: inverters feed the LV bus, self-consume 80% on-site and export 20% through net metering. Anti-islanding disconnects on grid loss, and the main design risk is the high LV fault level (24.31 kA) that squeezes the breaking-capacity margin.
| Source | Role | Share kW | Share |
|---|---|---|---|
| Grid 0.4 kV | base | 0 kW | 0% |
| Solar PV 800 kWp | variable | 640 kW | 100% |
3 · Design Process & Rationale
1. Requirement identification
800 kWp rooftop PV on a 0.4 kV grid connection, self-consumption + export.
2. Load & PV balance
800 kW site demand → 640 kW effective (0.8 kd); 800 kWp PV covers 100% renewable.
3. PV stringing
800 kWp → 250 kW-class string inverters, 1500 VDC MPPT, PR 0.846.
4. LV connection
0.4 kV switchgear + 300 mm² feeders; 640 kW at 0.4 kV → 24.31 kA fault level.
5. Anti-islanding & metering
Grid-tie inverters + anti-islanding relay on the PCC; 162,432 kWh export via net metering.
6. Power quality
THDi flagged (V6) → APF/SVG; PFC for reactive compensation.
7. Over-generation
160 kW instantaneous over-generation (800 vs 640) → export via metering (or curtail/store).
Pain Points → Solution → Evidence
PV export must not island the grid
Anti-islanding relay + grid-tie inverter on the PCC
Compliance pass; grid-connection approval in toConfirm
Inverter harmonics pollute the LV bus
APF/SVG active filtering
V6 THDi exceeds limit (warn)
800 kWp over-generates vs 640 kW demand
Export the 160 kW via net metering (or add storage)
V7 160 kW over-generation; economic export 162,432 kWh
0.4 kV fault level is punishing
25 kA gear + 300 mm² cable, verify Ssc
ikLv 24.31 kA, 1× margin (tight)
4 · Key Parameter Deep-Read
| Parameter | Value | Basis | Impact & Boundary |
|---|---|---|---|
| PV capacity | 800 kWp | 812,160 kWh/yr (P50), PR 0.846 | 100% renewable, LCOE $0.0562 Limited by roof area / orientation |
| Effective supply | 640 kW | 800 × 0.8 diversity | stdKva 674 Depends on demand profile |
| Self-consumption | 0.8 | Default | 649,728 kWh self-used, 162,432 kWh export Higher with storage |
| LV fault | 24.31 kA | 0.4 kV + 800 kW | 25 kA breaking = 1× margin (tight) Confirm Ssc; may need 36/50 kA gear |
| Grid connection | 0.4 kV + anti-islanding | Distributed PV | Net metering export Grid-code approval |
| Power quality | THDi (V6 warn) | Inverter harmonics | APF/SVG needed Filter sizing |
| Economics | $440,000 EPC | PV + LV connection | 6 yr payback, 18.15% IRR Feed-in tariff / curtailment |
5 · Drawing Deep-Read
The following drawings are shown for reference (full set in the configurator “View design document”):
6 · Operation Demo (Deep-Read)
Energy flow
PV 800 kW feeds the 640 kW site first, the 160 kW surplus exports via metering; the grid fills gaps; anti-islanding disconnects on grid loss — self-consumption + export at a glance.
Economics
812,160 kWh/yr, $87,713/yr saved; $440,000 EPC, 6 yr payback, 18.15% IRR, LCOE $0.0562/kWh, NPV $412,017, 487.3 t CO2 avoided/yr.
Power quality
THDi over the limit (V6) needs APF/SVG; PFC compensates reactive power — the key power-quality point for large 0.4 kV PV.
Fault & protection
0.4 kV fault 24.31 kA, 25 kA breaking (1× tight margin); anti-islanding 81U/81O disconnects on grid loss — the safety core of interconnection.
Other views (shown): Voltage profile · Scheme features · LCC (life-cycle cost) · Environmental
7 · Economics & Payback
EPC ≈ $440,000 (800 kWp PV + 0.4 kV connection). PV saves ≈$87,713/yr (self-consumption at $0.12/kWh + 0.2 export at $0.06/kWh); 6 yr payback, 18.15% IRR, 345% 25-yr ROI, LCOE $0.0562/kWh, NPV $412,017, 487.3 t CO2 avoided/yr. The high self-consumption ratio (0.8) is what drives the strong payback.
8 · FAQ
Can 800 kW PV connect at 0.4 kV?
How much does it generate?
What's the payback?
Do I need anti-islanding protection?
What about inverter harmonics?
What happens to the 160 kW over-generation?
How is the export metered?
What cables and switchgear?
How much CO2 does it avoid?
Special Considerations
- LV fault level 24.31 kA leaves only ~1× margin on standard 25 kA gear — confirm the actual grid Ssc and consider 36/50 kA switchgear.
- V6 THDi exceeds the limit (inverter harmonics) — add APF/SVG active filtering on the LV bus.
- V7 flags 160 kW instantaneous over-generation (800 kWp vs 640 kW demand) — export via net metering, or add storage to absorb it.
- Anti-islanding + grid-connection approval are mandatory (toConfirm: local grid code) — do not energize without utility sign-off.
- Feasibility-level; schematic drawings pending a licensed design institute.
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