VoltForge PRO v1.0

Off-Grid Solar Calculator — Panels, String Voc, Batteries, Cables & Inverter Sizing

Q: How are DC cable gauges and inline fuse ratings calculated?

Conductor gauge sizing evaluates NEC 75°C copper ampacity tables against round-trip length to keep voltage drop under 3%, pairing with ANL fuses rated at 1.25x peak continuous DC current.

Q: Why is cold-temperature panel Voc critical for MPPT selection?

PV module open-circuit voltage increases in cold weather. VoltForge applies a 1.15 safety multiplier to string Voc to prevent MPPT voltage overload.

Installer Design Suite & Quoting Engine

📋 Project Identification & Site Meta

Project / Job Name

Client Name

Site Location

Date / Revision

⚡ Quick Load Templates

Instantly populate equipment lists for common off-grid use cases:

High Current DC Bus Warning: Calculated MPPT output (A) on a 12V DC bus exceeds practical single-controller limits (80A). To reduce cable gauge thickness, resistive losses, and hardware costs, consider upgrading to a 24V or 48V DC bus.

1. Solar System Sizing — DC Bus & Environment

DC Bus Voltage

Battery Technology

Autonomy Cushion

Site Insolation (PSH)

Shading / Orientation Loss

Battery Temp Environment

⚠️ Low-Temperature LiFePO4 Charge Hazard: LiFePO4 cells must not be charged below 0°C without dedicated heating pads or a BMS low-temp charge cutoff. System capacity is derated by 35% for cold discharge performance.

Inverter Tare Draw (W)

Inverter Efficiency (%)

MPPT Max PV Input (V)

2. Appliance Load Profile — Daily Energy Consumption

Equipment Description	Watts	Qty	Hrs/Day	Motor?	Daily Wh

Hardware Specification

Daily DC Energy

Inverter SKU

Battery Storage

Solar Array & String

Cable Gauge & Protection Specs

Battery Cable Run (MPPT/Inverter → Battery)

PV Cable Run (PV Array → MPPT Combiner)

Battery Cable Gauge

PV Combiner → MPPT

ANL Fuse Rating

Commercial MPPT SKU

Budget & Backup Generator

Recommended Generator

Architecture Flow Schematic

PV Array

↓ Solar DC Generation

MPPT Controller

↓ DC Bus Charging

Battery Storage

↓ DC Bus Discharging (+Tare)

Pure Sine Inverter

Energy Load Distribution

Off-Grid Solar Sizing — Frequently Asked Questions

How does VoltForge calculate required battery capacity?

Battery storage is dimensioned using gross daily DC energy demand (AC loads adjusted for inverter efficiency plus continuous inverter standby tare draw). Total Wh is expanded by required days of autonomy, derated for battery depth-of-discharge (e.g., 85% for LiFePO4, 50% for AGM), and adjusted for ambient temperature factors.

How are DC cable gauges and inline fuse ratings calculated?

Battery-to-inverter conductor sizing is determined by maximum continuous DC current draw under peak inverter loading. VoltForge evaluates NEC 75°C copper ampacity tables against round-trip conductor length to ensure both thermal safety and acceptable voltage drop percentage (under 3%). ANL inline fuses are sized with a standard 1.25x safety factor over max continuous current.

Why is cold-temperature panel Voc critical for MPPT selection?

Photovoltaic module open-circuit voltage (Voc) increases in low ambient temperatures. VoltForge applies a conservative 1.15 multiplier to PV string Voc to prevent cold-morning over-voltage conditions that can permanently damage MPPT charge controller inputs.

Can I export proposals directly to clients?

Yes. VoltForge includes one-click CSV export for spreadsheet Bill of Materials (BOM) editing, direct clipboard spec copying, and a built-in print stylesheet that formats the current system design into a clean PDF proposal document.