Off-grid, RV & cabin
Enter your panel, battery, and inverter sizes. See total system weight and how much of your vehicle's payload it uses.
How it works Remote systems are easy to neglect. The panel degradation calculator in our Maintenance & Lifespan section can help you budget for the maintenance that keeps output from slipping.
Step 1
From your other sizing calculations.
Step 2
Found on your vehicle's door sticker or manufacturer specifications.
Step 3
Know exactly how much room remains for everything else you carry.
For a 400-watt panel array, a 300Ah 24V LFP battery, and a 3,000-watt inverter, total system weight comes to about 319 pounds, with the battery bank making up the large majority of that total. This is a manageable weight for most vans and trucks, but worth confirming against your specific vehicle's rated capacity. The DOE's overview of battery and energy storage technology lays out the same rules from the regulator's side.
For a 319-pound system against a 1,500-pound vehicle payload capacity, the system uses about 21% of available payload, leaving roughly 1,181 pounds for passengers, gear, water, and everything else you carry day to day. Water alone can add hundreds of pounds when tanks are full, so weigh your full loadout, not just the solar system, against your vehicle's rating.
Battery weight typically dominates total system weight by a wide margin, and LFP batteries weigh dramatically less than lead-acid batteries of equivalent usable capacity, making chemistry choice the single biggest lever for reducing total system weight in a mobile setup. If weight is a genuine concern, this is the first place to look before trimming panel or inverter size. Pair this with the battery lifespan estimator to see the full picture before you commit.
Exceeding payload capacity affects handling, braking distance, and tire wear, and can be a safety and legal issue depending on your vehicle's rated limits and local regulations. If your system pushes close to or over the limit, reducing battery capacity or choosing lighter components becomes a genuine safety consideration, not just a preference for a lighter build. FMCSA's federal vehicle safety regulations cover the legal side of payload limits for anyone unsure where their vehicle's rating actually comes from.
Check the tiny house battery sizing calculator if battery weight is your biggest concern, and see the battery voltage selection tool for how voltage choice affects wiring weight as well. The battery chemistry weight comparison tool in our battery chemistry storage tools breaks the LFP-versus-lead-acid weight gap down further across a range of capacities, and the battery lifespan estimator in our maintenance and lifespan tools is worth checking too, since a lighter battery isn't worth much if it needs replacing twice as often. DOE's overview of battery and energy storage technology covers the chemistry fundamentals behind this weight difference.
Questions
For a 400-watt panel array, a 300Ah 24V LFP battery, and a 3,000-watt inverter, total system weight comes to about 319 pounds, with the battery bank making up the large majority of that total.
For a 319-pound system against a 1,500-pound vehicle payload capacity, the system uses about 21% of available payload, leaving roughly 1,181 pounds for passengers, gear, water, and everything else you carry.
Battery weight typically dominates total system weight by a wide margin, and LFP batteries weigh dramatically less than lead-acid batteries of equivalent usable capacity, making chemistry choice the single biggest lever for reducing total system weight in a mobile setup.
Exceeding payload capacity affects handling, braking distance, and tire wear, and can be a safety and legal issue depending on your vehicle's rated limits. If your system pushes close to or over the limit, reducing battery capacity or choosing lighter components becomes a genuine safety consideration, not just a preference.
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