RV Solar Calculator: Size the System You Actually Need

For a couple running a 12V fridge, LED lights, Starlink, a laptop, and a vent fan — roughly 1,800–2,500 Wh per day — you typically need 400–600 watts of panels and 200–400 Ah of LiFePO4 storage. Adding a residential fridge or running roof AC off-grid pushes the panel count to 800W+ and the battery bank to 600 Ah or more. The calculator above prices both scenarios.

LiFePO4 wins almost every cost-of-ownership analysis in 2026. A single 100Ah LiFePO4 battery from BougeRV or Battle Born delivers ~90 Ah of usable capacity for 3,000–5,000 cycles. A 100Ah AGM delivers ~50 Ah usable for 500–800 cycles. Over a 10-year window, AGM ends up costing more per usable kWh and weighs twice as much. AGM still makes sense for weekend-only use or when upfront cost is the hard constraint.

Entry-tier 100W panels average ~7 sq ft each. Mid-tier 200W bifacials average ~11 sq ft. Premium 550W N-type panels are roughly 28 sq ft. Subtract your roof AC (roughly 15 sq ft), vents, and antennas before comparing to usable roof space. If roof area is the binding constraint, bifacial mid-tier panels are the best watts-per-square-foot value in 2026.

For boondockers, payback depends on the nightly fee difference versus paid campgrounds plus avoided generator fuel. A couple spending 120 nights per year boondocking (vs $45/night state-park sites) saves $5,400 annually — payback in roughly 7 months. For weekend-only users, payback rarely beats 5 years. Solar is a lifestyle purchase for most; financial ROI is the bonus for full-timers.

Most RVers 55+ who are comfortable with basic electrical work install their own roof-panel system in a weekend. The hard parts are running wire through the roof (use a proper gland — not caulk) and wiring the battery bank safely. Professional installation runs $800–$2,000. If you're swapping from AGM to LiFePO4 and keeping the existing charge controller, the swap is essentially a 2-hour job.

Yes, but with caveats. A standard 13,500 BTU roof AC draws ~1,500W running plus a startup surge of 3,000W+. You need a soft-start kit ($250–$400), a 3,000W+ inverter, and at least 600 Ah of LiFePO4 at 12V (or 300 Ah at 24V). Most successful setups use 800–1,200W of panels dedicated to AC duty. We don't recommend this for first-time solar buyers — size it after you've lived with a simpler setup for a year.

Peak sun hours measure effective solar energy: one peak sun hour equals 1,000 W/m² for one hour. A state with 6.5 peak sun hours per day (Arizona) produces nearly twice the energy per panel as one with 3.6 peak sun hours (Washington). The calculator uses annual state averages from NREL; if you boondock in a single region year-round, you can weight your sizing toward that region's number.

MPPT (maximum power point tracking) controllers harvest 15–30% more energy than PWM controllers under the same panel and battery conditions. At 2026 prices, a 40A MPPT from Renogy is around $129. The extra harvest covers the price difference in one season of boondocking. PWM is fine only for weekend-only setups with a single 100W panel.

Yes for almost everything sensitive — CPAPs, newer TVs, laptops, variable-speed motors, LED lighting with dimmers, coffee makers with digital controls. Modified sine inverters are 30–40% cheaper but can cause hums, flicker, and motor damage. We recommend pure sine for any RV built after 2015 because the on-board converter and appliances assume clean AC.

We use a 0.75 system efficiency derate (temperature, wiring losses, panel mismatch, soiling), LiFePO4 DoD of 90% (manufacturer spec — Battle Born and BougeRV both publish full 90% usable), AGM DoD of 50% (cycle-life preservation), and a 25% MPPT safety margin on panel-to-battery amperage. These match the standards published by the Renewable Energy Education Project and the defaults used by Victron's sizing tool. If you're getting very different numbers from another calculator, check what efficiency derate they assume.