DEC Group Inc. · Free Solar Calculator App

Size your solar system in minutes — not weeks

Solar Pal uses real astronomical solar calculations to compute the exact number of solar panels, battery bank size, wiring configuration, and system losses for any location on earth. No engineering background required.

3

Step Wizard

4

Battery Chemistries

12

Months Modelled

$0

Personal Use

Free for personal use Works fully offline No account required All data stays on your device
Who Solar Pal Is For

A data-driven starting point for any solar project

Whether you're designing an off-grid cabin system or sizing a battery backup for a grid-tied home, Solar Pal gives you numbers you can take straight to your electrician or solar installer.

Homeowners

Understand system size and cost before calling an installer.

Off-grid owners

Cabins, farms, and remote worksites needing reliable standalone power.

Contractors & installers

A fast, repeatable pre-design scoping tool for client estimates.

Students & educators

Study real renewable energy system design with live calculations.

DIY solar builders

Plan your own residential installation with confidence.

How It Works

A guided three-step solar system wizard

Solar Pal's guided workflow prevents common sizing mistakes by ensuring all required data is collected before any calculation runs.

1

Site Information

Enter your project name, GPS coordinates (or auto-detect), panel direction, tilt angle, panel capacity, battery chemistry, system voltage, and days of autonomy.

2

System Loads

Build a complete inventory of electrical loads. Enter power draw and daily duration — Solar Pal totals watt-hours and daily energy demand in real time.

3

Computed Results

Get panel count, array capacity, battery bank size, wiring configuration, a monthly peak sun hours chart, itemized losses, and a full system summary.

Built on Real Solar Science

Astronomical calculations, not generic tables

Solar Pal does not use generic solar irradiance tables or hardcoded regional values. Every calculation is derived from real astronomical formulas applied to your specific latitude, panel tilt, and azimuth.

  • Solar declination by day-of-year across all twelve calendar months
  • Sunrise hour angle computed from latitude and declination
  • Surface irradiance adjusted for panel tilt and compass orientation
  • Worst-case design month automatically identified and applied to sizing
Why this matters: this approach ensures the system is always sized for the month with the least solar energy — typically December at northern latitudes — so it never falls short in winter while still generating a useful surplus in summer.

Ready to size your solar system?

Install Solar Pal on your phone in under a minute. No App Store download, no account, no cost for personal use.