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RV Solar Calculator — Panel, Battery & Controller Sizing

Calculate how many solar panels, battery capacity, and controller amps your RV needs for off-grid camping

Solar Panels Needed

2 × 200W

Total Watts

400W

Battery

313 Ah

Controller

42A

Wh
hrs

Common RV Appliance Reference

LED Lights (5 bulbs)50W × 5h = 250 Wh
12V Fridge50W × 24h = 1200 Wh
Laptop Charger60W × 3h = 180 Wh
Phone Charger (2x)20W × 2h = 40 Wh
Water Pump60W × 0.5h = 30 Wh
Vent Fan40W × 6h = 240 Wh
TV / Monitor60W × 3h = 180 Wh
Coffee Maker600W × 0.17h = 102 Wh
days

Solar Panels Needed

2 × 200W

400 watts total

Battery Bank

313 Ah

Battery Capacity

3.8 kWh

Controller Size

42A MPPT

Daily Production

1,700 Wh

Battery Bank Details

TypeLithium (LiFePO4)
Depth of Discharge80%
System Voltage12V
Autonomy2 days

Sizing Tip

Add 15–20% extra panel capacity to account for cloudy days, panel aging, and shading. MPPT controllers are 20–30% more efficient than PWM.

Frequently Asked Questions

Q

How many solar panels does an RV need?

Most RVs need 2–4 solar panels (400–800W total) for moderate use. The exact number depends on your daily energy consumption divided by peak sun hours and system efficiency (about 85%). A typical boondocking setup using 1,500 Wh per day in 5 sun hours needs roughly 400W of panels.

  • Minimal use (lights, phone, fan): 200–400W total, 1–2 panels
  • Moderate use (fridge, laptop, TV): 400–800W total, 2–4 panels
  • Heavy use (AC, microwave, coffee maker): 800–1,200W+ total, 4–6 panels
  • MPPT controllers add 20–30% efficiency over PWM controllers
  • Account for 15–20% extra capacity for cloudy days and panel aging
Usage LevelDaily WhPanels (200W)Battery (12V)
Minimal500–800 Wh1–2100–150 Ah
Moderate1,200–1,800 Wh3–4200–300 Ah
Heavy2,500–4,000 Wh5–8400–600 Ah
Q

What size charge controller do I need for my RV?

Divide your total solar panel wattage by your system voltage, then add 25% overhead. A 600W array on a 12V system needs at least 63A (600/12 × 1.25). MPPT controllers are recommended over PWM for RV use because they harvest 20–30% more energy.

  • Formula: Controller Amps = (Total Panel Watts / System Voltage) × 1.25
  • 600W on 12V: 600/12 × 1.25 = 63A MPPT minimum
  • 800W on 24V: 800/24 × 1.25 = 42A MPPT minimum
  • MPPT controllers cost more but recover the investment in 20–30% more energy
  • Always round up to the next standard controller size (30A, 40A, 50A, 60A)
Q

Lithium vs AGM batteries for RV solar: which is better?

Lithium (LiFePO4) batteries are the better long-term choice for RV solar despite costing 2–3x more upfront. They offer 80% depth of discharge vs 50% for AGM, 3,000+ cycle life vs 600, and weigh 40–60% less. Over their lifespan, lithium batteries cost less per cycle.

  • Lithium: 80% DOD, 3,000 cycles, 0.26 lbs/Ah, ~$4.50/Ah upfront
  • AGM: 50% DOD, 600 cycles, 0.60 lbs/Ah, ~$2.00/Ah upfront
  • For 200Ah usable: lithium needs 250Ah ($1,125), AGM needs 400Ah ($800) but weighs 2.3x more
  • Lithium cost per cycle: $0.38 vs AGM: $1.33 — lithium saves 71% long-term
  • Lithium cannot charge below 32°F without a heated BMS
FeatureLithium (LiFePO4)AGM
Depth of Discharge80%50%
Cycle Life3,000+~600
Weight per 100Ah26 lbs60 lbs
Cost per Ah$4.50$2.00
Cost per Cycle$0.38$1.33
Q

How many peak sun hours do I get for RV solar?

Peak sun hours vary by location and season. The US Southwest averages 6–7 peak sun hours, the Southeast 4–5, and the Pacific Northwest 3–4 in winter. Use NREL’s PVWatts tool for site-specific data. Most RV solar calculations use 4–5 hours as a conservative estimate.

  • Southwest US (AZ, NM, NV): 6–7 peak sun hours year-round
  • Southeast US (FL, TX, GA): 4.5–5.5 peak sun hours average
  • Midwest US (OH, IL, MN): 3.5–5 peak sun hours depending on season
  • Pacific Northwest (WA, OR): 3–4 in winter, 5–6 in summer
  • Use 4–5 hours as a conservative planning estimate for most US travel
Q

Can RV solar run an air conditioner?

Running a 13,500 BTU RV AC requires 1,300W continuous (3,800W starting surge). This demands a large solar system: 1,500–2,000W of panels, 400–600Ah lithium batteries, and a 3,000W+ inverter. Most RV solar setups can run AC for only 3–4 hours per day with full sun recharging.

  • 13,500 BTU AC: 1,300W running, 3,800W starting surge
  • 4 hours of AC = 5,200 Wh daily — requires ~1,200W of panels in 5 sun hours
  • Battery bank: 5,200 Wh / (12V × 0.8 DOD) = 542 Ah lithium minimum
  • 3,000W pure sine wave inverter required for motor startup surge
  • Soft-start kits reduce AC starting surge from 3,800W to ~1,500W

Example Calculations

1Moderate Boondocking Setup

Inputs

Daily Consumption1,500 Wh
Peak Sun Hours5
Battery TypeLithium (LiFePO4)
System Voltage12V
Panel Size200W each
Days Autonomy2

Result

Solar Panels Needed4 × 200W (800W)
Battery Bank313 Ah
Charge Controller84A MPPT
Daily Production3,400 Wh

1,500 Wh / (5 hrs × 0.85 × 0.97) = 364W minimum. Rounded to 4 × 200W = 800W. Battery: (1,500 × 2) / (12 × 0.8) = 313 Ah. Controller: (800 / 12) × 1.25 = 84A.

2Weekend Camper (Minimal Setup)

Inputs

Daily Consumption600 Wh
Peak Sun Hours5
Battery TypeAGM
System Voltage12V
Panel Size100W each
Days Autonomy1

Result

Solar Panels Needed2 × 100W (200W)
Battery Bank100 Ah
Charge Controller21A MPPT
Daily Production850 Wh

600 Wh / (5 × 0.85 × 0.97) = 146W minimum. 2 × 100W = 200W. Battery: (600 × 1) / (12 × 0.5) = 100 Ah. Controller: (200 / 12) × 1.25 = 21A.

3Full-Time RVer with AC

Inputs

Daily Consumption3,500 Wh
Peak Sun Hours6
Battery TypeLithium (LiFePO4)
System Voltage24V
Panel Size400W each
Days Autonomy2

Result

Solar Panels Needed2 × 200W (400W)
Battery Bank365 Ah
Charge Controller42A MPPT
Daily Production1,700 Wh

3,500 / (6 × 0.85 × 0.97) = 708W minimum. 2 × 400W = 800W. Battery: (3,500 × 2) / (24 × 0.8) = 365 Ah at 24V. Controller: (800 / 24) × 1.25 = 42A.

Formulas Used

Solar Panel Sizing

Panel Watts = Daily Wh / (Sun Hours × 0.85 × 0.97)

Calculates total solar panel wattage needed based on daily energy use, available sunlight, and system losses from inverter efficiency and wire resistance.

Where:

Daily Wh= Total daily energy consumption in watt-hours
Sun Hours= Peak sun hours per day at your location (typically 4–6)
0.85= System efficiency factor (inverter, temperature, shading losses)
0.97= Wire loss factor (3% typical copper wire loss)

Battery Bank Sizing

Battery Ah = (Daily Wh × Days) / (Voltage × DOD)

Determines battery bank capacity in amp-hours, accounting for autonomy days and safe depth of discharge for the chosen chemistry.

Where:

Daily Wh= Total daily energy consumption in watt-hours
Days= Number of days without sun (autonomy)
Voltage= System voltage (12V, 24V, or 48V)
DOD= Depth of discharge (0.8 for lithium, 0.5 for AGM/lead-acid)

Charge Controller Sizing

Controller Amps = (Total Panel Watts / System Voltage) × 1.25

Sizes the MPPT charge controller with a 25% overhead factor to handle peak output and prevent controller overload.

Where:

Total Panel Watts= Combined wattage of all solar panels
System Voltage= Battery bank voltage (12V, 24V, or 48V)
1.25= 25% safety overhead for peak conditions and controller headroom

RV Solar System Sizing Guide

Sizing an RV solar system correctly is the difference between comfortable off-grid camping and constantly worrying about battery levels. The three critical components — solar panels, battery bank, and charge controller — must be balanced to match your energy consumption and the amount of sunlight available at your camping locations.

The sizing process starts with your daily energy consumption in watt-hours. Add up the wattage of every appliance you plan to use and multiply by hours of daily operation. A typical moderate RV setup (fridge, lights, laptop, phone chargers, water pump, vent fans) consumes 1,200–1,800 Wh per day. From there, divide by peak sun hours and system efficiency (85%) to get your required panel wattage.

Battery bank sizing depends on how many days you want to operate without sun (autonomy) and your battery chemistry’s depth of discharge. Lithium batteries can safely discharge to 80% DOD, while AGM and lead-acid should stop at 50% DOD. This means you need nearly twice the rated capacity with lead-acid compared to lithium to store the same usable energy.

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Last Updated: Mar 25, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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