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1.1.4 Solar Charging

Cascadia 4x4 Solar Panel

Type: Flexible Monocrystalline Solar Panel

Model: Cascadia 4x4 80W Hood Solar Panel (VSS System for TJ/LJ 2003-2006)

Manufacturer: Cascadia 4x4

Product Page: Cascadia 4x4 VSS System

Note: VSS System includes MPPT controller, but using BCDC's built-in solar MPPT instead (panel only from VSS kit)

Electrical Specifications

Power Output:

  • Maximum Power @ STC: 80W
  • Optimum Operating Voltage (Vmp): 40.1V
  • Optimum Operating Current (Imp): 1.95A
  • Open Circuit Voltage (Voc): 46.8V
  • Short Circuit Current (Isc): 2.23A

BCDC Compatibility: Voc 46.8V within BCDC solar input range (9-48V) at STC (25°C)

Cold Weather Voc

Solar panel Voc increases in cold temperatures (~0.35%/°C). At 0°F (-18°C), Voc may reach ~53V, exceeding BCDC's 48V limit. The BCDC Alpha has overvoltage protection - soft fault (LED warning) progressing to hard fault as voltage increases. See Optional Overvoltage Protection below for automatic disconnect solution.

Physical Specifications

  • Dimensions: 68 × 66 × 5 cm (27 × 26 × 2 in)
  • Weight: 2.6 kg (5.7 lb)
  • Top Sheet Material: ETFE (fluoropolymer)
  • Mounting Method: SolarClasp™ adhesive system
  • Connector Type: MC4 (standard solar connectors)
  • Cable Length: 190 cm (74.8 in)
  • Mounting: Permanently adhered to hood surface
  • Connection: Wired to BCDC Alpha 50 solar input

Wiring

Solar Panel Connections:

  • Positive (+): Panel output → BCDC Alpha 50 solar input positive terminal
  • Negative (-): Panel output → Chassis ground (NOT to BCDC negative)
  • Wire Gauge: 10 AWG minimum (for 2.23A Isc with safety margin)
  • Routing: Hood → Firewall → BCDC location in passenger rear wheel well
  • Maximum Current: 2.23A (Isc) - well within BCDC solar input capacity

VSS System Note: VSS kit includes standalone MPPT controller - not used. BCDC has built-in MPPT on solar input, providing Green Power Priority and unified charge control.

Important: Solar negative connects to chassis ground per REDARC specifications. The BCDC requires a common ground system where all batteries and components share the same ground reference (vehicle chassis).

Function

80W panel maintains AUX battery during extended stops via BCDC solar input. Full sun panel output at optimal conditions: 80W (1.95A @ 40V), variable in partial sun/clouds.

Panel-side vs battery-side current: The 1.95A figure is panel-side current at the panel's ~40V operating voltage (40V × 1.95A ≈ 78W). The BCDC's MPPT steps that down to battery charge voltage: 78W ÷ ~13.4V ≈ ~5.8A to the AUX battery.

BCDC Green Power Priority: Solar input used first when available, alternator supplements to reach 50A total charging current. Battery-side contribution by condition:

  • Full sun: ~5.8A (reduces alternator load from 50A to ~44A)
  • Partial sun: Variable, proportional to available irradiance
  • Overcast/Night: 0A (BCDC uses alternator only)

See BCDC Alpha 50 for complete charging system details.

Installation: See Section 1 Installation Checklist

Critical: Verify polarity before connection - reverse polarity damages BCDC.

Optional Overvoltage Protection

To automatically disconnect the solar panel when cold-weather Voc exceeds the BCDC's 48V limit, install an adjustable overvoltage disconnect module.

Over/Under Voltage Protection Relay Module

  • Type: Compact PCB module with adjustable thresholds
  • Example: Amazon DC Over/Under Voltage Relay Module (~$15-25)
  • Voltage Range: DC 36V version has overvoltage adjustment range of 39-51V
  • Delay: Adjustable 0.1-15s (prevents nuisance trips from brief voltage spikes)
  • Contacts: Relay with NO/NC contacts, rated 10A (solar is only 2.2A)
  • Power: Self-powered from monitored circuit (no separate 12V tap needed)
  • Size: Compact (~2" x 2") - mount near BCDC or in small enclosure

Wiring Diagram

Solar Panel (+) ──┬── Voltage Module Sense Input
                  │
                  └── Voltage Module Relay (NC) ──── BCDC Solar Input (+)

Solar Panel (-) ────────────────────────────────── Chassis Ground

Voltage Module Power: Self-powered from solar panel voltage

Configuration

Setting Value Purpose
Overvoltage Threshold 47V Disconnect before BCDC 48V limit
Undervoltage Threshold Disabled or 10V Don't disconnect at low voltage
Reconnect Hysteresis ~3V (44V reconnect) Prevent rapid cycling
Trip Delay 1-2 seconds Ignore brief voltage spikes

Operation

  1. Normal conditions (Voc < 47V): Relay closed, solar charges normally
  2. Cold weather (Voc > 47V): Relay opens, disconnects solar from BCDC
  3. Panel warms up (Voc drops < 44V): Relay closes, charging resumes automatically
  4. BCDC protected: Never sees voltage above 47V

Installation Notes

  • Mount module in weatherproof location (near BCDC in passenger rear wheel well, or sealed enclosure)
  • Use MC4 inline connectors for easy solar disconnect during installation
  • Consider conformal coating on PCB for moisture protection
  • Test threshold settings before final installation

Alternative: Series Diode Voltage Drop

For a passive (no electronics) solution, install 4-5 series rectifier diodes (10A10 type) in the solar positive line:

  • Voltage drop: ~0.7V per diode × 5 = 3.5V permanent drop
  • Result: Reduces 53V cold Voc to ~49.5V (still marginal)
  • Cons: Permanent ~8% power loss, generates heat
  • Pros: No moving parts, no adjustment needed

Recommendation: The relay module is preferred - no power loss during normal operation and provides automatic protection only when needed.

Outstanding Items

High (3)

  • JL Audio amp feed: 100A CB exceeds 4 AWG ampacity (95A @ 20°C) (#149) — The amp's battery feed is 4 AWG (95A continuous @ 20°C per the project reference table) protected by a 100A CB. The amp's internal 80A fuse is downstream and does not protect the battery-to-amp run against a chafe/short. This violates the project's "CB protects the wire" rule and is NOT covered by STANDARDS-EXCEPTIONS (which only sanctions the SwitchPros/SafetyHub 150A-on-2-AWG case).
  • START+ auxiliary distribution busbar + breakers for relocated fan / iBooster / TCU (#135) — Relocating the radiator fan, iBooster, and TCU from the PMU to START-battery-direct adds three breaker-protected feeds. All three loads are forward (engine bay / transmission) while the START battery is rear, so the chosen architecture mirrors the AUX forward-feed pattern: a single master-protected feed forward to an engine-bay busbar rather than three long runs or ~9 stacked lugs on the battery post.
  • Dakota Digital Panel Mounting (#39) — HDPE sheet dimensions and location for the Dakota Digital panel.

📋 Medium (10)

📝 Low (1)

🔍 Verify (2)

Build Tasks

  • Order overvoltage protection relay module (DC 36V version, ~$15-25)
  • Determine mounting location for voltage module (near BCDC or inline with solar wiring)
  • Test and configure voltage thresholds before final installation (47V disconnect, 44V reconnect)