FranklinWH System Architecture¶
This document clarifies the AC-coupled vs DC-coupled architecture of FranklinWH systems.
Overview¶
FranklinWH uses different coupling architectures depending on the product line:
| Product | Coupling | Solar Input | Battery Coupling | Region |
|---|---|---|---|---|
| aGate X | AC-Coupled | 2x 63A AC circuits | AC (internal inverter) | AU/US |
| aPower S | Hybrid | 4x MPPT DC + AC inputs | DC | US |
| aPower 2 | DC-Coupled | MPPT DC inputs | DC | US |
| aPower X | DC-Coupled | MPPT DC inputs | DC | US |
aGate X (AC-Coupled) - Most Common¶
Architecture Diagram¶
Solar Panels → AC Solar Input (63A) →┐
├→ aGate Inverter → AC Output → Home/Grid
Battery ↔ AC Battery Port ↔ Inverter ┘
Key Characteristics¶
- Solar: Connects via AC inputs (not DC MPPT)
- Battery: AC-coupled (inverter built into aGate)
- Remote Solar: Supported via aPbox or aHub accessories
- Monitoring: Model 502 shows solar AC output, Model 714 shows battery DC power
Why "AC-Coupled"?¶
- Solar panels connect to AC inputs (like a regular appliance)
- Battery stores AC power (converted by internal inverter)
- No high-voltage DC wiring to battery
SunSpec Models for aGate X¶
| Model | Purpose | Notes |
|---|---|---|
| 701 | Grid/AC measurements | Primary AC monitoring |
| 714 | Battery DC status | DC power, voltage, current |
| 502 | Solar AC output | AC-coupled solar production |
aPower S (Hybrid)¶
Architecture Diagram¶
Solar Panels → DC MPPT (4x) → DC Bus → Battery
↓
Inverter → AC Output → Home/Grid
↑
Solar Panels → AC Input ──┘
Key Characteristics¶
- Solar: BOTH DC MPPT (4x) AND AC inputs
- Battery: DC-coupled to DC bus
- Flexibility: Can accept both DC and AC solar sources
Common Misconceptions¶
"PV" in DERMode Means DC-Coupled? ❌¶
The SunSpec DERMode register (Model 701) bit 0 is labeled "PV" but this refers to solar generation, not DC-coupling. On the aGate X: - Bit 0 = Solar active (via AC inputs) - Bit 1 = Battery active - The "PV" label is misleading for AC-coupled systems
Model 502 Solar Power is DC? ❌¶
Model 502 (Solar AC Output) shows AC power even though the model name suggests DC. For aGate X: - Solar panels → AC inputs → Inverter → Model 502 shows AC output - This is different from MPPT DC measurements on DC-coupled systems
Power Flow Summary (aGate X)¶
┌─────────────────┐
Solar (AC) ─────┤→ aGate X ├──→ AC Output → Home
(2x 63A) │ (Inverter) │
│ │
Battery (AC) ←──┤←── (AC Port) ├──→ Grid
└─────────────────┘
Power Equation (AC-Coupled)¶
Note: All values are AC power measurements. Battery DC power (Model 714) is separate from AC power flow.
Accessories¶
aPbox (Remote Solar Receiver)¶
- Purpose: Add remote solar panels to aGate X
- Connection: Wireless or wired to aGate
- Architecture: Still AC-coupled (aPbox has its own inverter)
aHub (Solar Aggregator)¶
- Purpose: Connect multiple solar arrays to aPower S
- Connection: DC or AC depending on configuration
- Architecture: Maintains DC-coupling for aPower S
Smart Circuits¶
- Purpose: Load management and backup circuits
- Connection: AC panel integration
Generator Module¶
- Purpose: Backup generator integration
- Connection: AC input to aGate
Status Display Corrections¶
Before (Incorrect)¶
This implied DC-coupled hybrid system.After (Correct)¶
DER Type: Battery+Solar (AC-Coupled)
Architecture: AC-Coupled (aGate X)
Solar Inputs: 2x 63A AC circuits (+ remote via aPbox/aHub)
Implications for Control¶
AC-Coupled (aGate X)¶
- Advantage: Safer installation (no HV DC)
- Efficiency: Double conversion (DC→AC→DC→AC for battery storage)
- Monitoring: Model 714 shows battery DC, Model 502 shows solar AC
- Control: WSetPct controls battery AC power
DC-Coupled (aPower S/2)¶
- Advantage: Higher efficiency (single conversion)
- Installation: Requires HV DC wiring
- Monitoring: Model 714 shows battery DC, MPPT shows solar DC
- Control: WSetPct controls battery AC power
References¶
- FranklinWH aGate X Datasheet
- FranklinWH aPower S Datasheet
- SunSpec Alliance DER Model Specification
Last Updated: February 22, 2026