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Off-grid electrical planner

Choose a bus or van platform, then build one connected plan: daily loads and solar array, usable battery capacity, generator backup, and the physical space the battery bank actually needs. Free to use and experiment with — saving a plan to come back to just needs one free verified account.

1. Choose the conversion platform

Vehicle geometry feeds the roof-fit estimate and the battery-compartment presets below.

Vehicle type
Interior length—buildable / cargo
Interior width—floor-width basis
Interior height—ceiling-height basis
Floor / roof area—gross rectangle
Interior volume—before cabinetry
Long wall area—both long walls

2. Daily loads and solar array

Select appliances, edit real-world wattage and runtime, then size the array for the worst month.

Use Appliance Qty Watts each Hours/day Daily Wh Surge W On generator

Solar conditions

Peak-sun-hour presets are planning starting points, not site guarantees. Verify the worst-month value for the places and seasons where the vehicle will actually be used.

Panel and roof assumptions

The roof-fit check uses the gross rectangular roof. Roof vents, air conditioners, curves, emergency hatches, racks, walkways, edge setbacks, and shading must be deducted manually — or laid out precisely in the Roof Layout Planner.
Daily load—including 20% overhead
Calculated array——
Worst-month harvest——
MPPT current——

3. Battery bank sizing

Turn daily energy use into a nameplate bank size, amp-hours, and a series/parallel module count.

Energy target

System and chemistry

Efficiency assumptions

Module dimensions
—
—
Required nameplate bank——
Required capacity——
Module configuration——
Selected-module bank——

4. Generator planner

Generator load selection comes from the "On generator" checkboxes in the Loads & Solar table.

Selected running loads

Continuous load—selected appliances
Largest surge—single largest startup

Charging target

—

Derating conditions

—
Recommended generator——
Generator class—round up to an available continuous-rated unit
Charging target——
50% to full—idealized battery-only recharge time
Generator nameplates, inverter-generators, chargers, and high-frequency inverter loads do not all behave identically. Confirm continuous output, surge duration, charger input limits, power factor, fuel type, and manufacturer derating before purchase.

5. Battery layout designer

Test the top-down module footprint, rotate batteries, drag them into position, and use a second layer only when compartment height allows.

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Live project data (JSON) 

  


 


 

  This planner uses steady-state off-grid electrical formulas similar to common solar and battery
  calculators, but it is not a substitute for a licensed electrician or an NEC/ABYC-compliant design.
  Use it for planning, then verify with a professional. See the
  solar setup guide and the
  battery system guide
  for how these numbers translate into real parts.
 




  











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