Daily Energy Usage
0Wh/day
0.00 kWh/day after your 20% safety buffer.
Quick Start
Load a sample profile
Not sure where to begin? Pick the profile closest to your trip style, then fine-tune everything below.
Step 1
System settings
“Usable” means how much of the rated capacity you can safely use before recharging. Lithium gives you more of what you pay for.
12V is the RV standard. Larger systems often move to 24V or 48V to keep wiring and currents manageable.
Most RV users can use 4 to 5 hours as a starting point. Cloudy areas may use 3 or less. Desert/sunny areas may use 6+.
Adds extra energy for unexpected usage.
How long your battery should last without meaningful solar charging.
Accounts for losses from wiring, inverter, charge controller, temperature, and dust.
Step 2
Add the devices you want to run
Quick-add common RV devices, then adjust the watts, quantity, and hours per day. Check AC for anything that plugs into a normal wall outlet.
Quick add
Your device list
No devices yet.
Use the quick-add buttons above, load a sample profile, or add a custom device below.
Tip: the wattage label is usually printed on the device or its power brick. For devices that cycle on and off (like fridges), the hours estimate matters a lot.
Step 3
Get your results
Results also update automatically as you type. Saving keeps your inputs on this device only — nothing is sent anywhere.
Results
Your estimated system size
Recommended Battery Capacity
0Ah @ 12V
0 Wh usable needed · 0 Wh total bank.
Usable portion based on battery type
Recommended Solar Array
0W
0 × 100W panels or 0 × 200W panels.
Charge Controller
0A
Includes a 25% safety margin on array output.
PWM or MPPTInverter (AC Devices)
—
You may not need a large inverter unless you plan to run AC devices.
System Notes & Warnings
Reality check on big appliances: Air conditioners, electric heaters, microwaves, and induction cooktops require large amounts of power. For many RV users, propane or generator power may be more practical for these devices.
This tool provides general estimates for planning purposes only. RV electrical systems can involve high currents, batteries, wiring, fuses, and inverters. Incorrect installations can cause equipment damage, fire, or injury. Consult manufacturer specifications and a qualified electrician or RV solar installer before purchasing or installing equipment.
Plain English
What these numbers mean
Shopping List
Your equipment checklist
Generated from your current inputs. Use it as a starting point and always verify specifications before buying.
Gear
Recommended Equipment Categories
Affiliate disclosure: As an Amazon Associate, this site may earn from qualifying purchases. Product availability and prices change frequently. We link to broad product categories, not specific items — always compare specifications and reviews yourself.
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The beginner’s guide to RV solar power
How to Size an RV Solar System
Sizing comes down to five simple steps, and this calculator does all five for you:
- List your devices. Write down everything that uses power: lights, fans, pumps, fridge, phone chargers, laptops, CPAP, and so on. Check the label on each device for its wattage.
- Estimate daily usage. Multiply each device’s watts by the hours it runs per day (and by quantity). Add them up to get watt-hours per day (Wh/day).
- Size your battery bank. Decide how many days of autonomy you want, then divide by your battery’s usable depth of discharge (about 50% for lead-acid/AGM, 80% for lithium).
- Size your solar array. Divide your adjusted daily usage by your peak sun hours and an efficiency factor (around 75–85%).
- Match the supporting gear. Pick a charge controller with enough amperage, correctly sized wiring and fuses, and an inverter only if you truly need AC power.
When in doubt, be conservative about sun hours and generous about usage — a slightly oversized system is far more pleasant than one that runs flat on a cloudy day.
Battery Types for RVs: Lead-Acid, AGM, and Lithium
The battery is usually the biggest part of the budget, so understanding the trade-offs matters.
| Battery type | Safely usable | Typical lifespan | Upfront cost | Notes |
|---|---|---|---|---|
| Flooded Lead Acid | ~50% | Shorter | Lowest | Needs ventilation and periodic water checks. |
| AGM | ~50% | Moderate | Moderate | Sealed, low maintenance, good starter choice. |
| Lithium LiFePO4 | ~80% | Longest | Highest | Lighter, more cycles, more usable energy per rated Ah. |
A 100Ah lithium battery therefore delivers roughly as much usable energy as a much larger lead-acid bank. Over many cycles, lithium can be competitive on cost despite its higher sticker price — but AGM remains a sensible, budget-friendly option for lighter use.
How Many Solar Panels Do I Need?
The core formula is: solar watts = daily watt-hours ÷ (peak sun hours × system efficiency). For example, if you use 800 Wh/day with 4.5 sun hours and 80% efficiency, you need about 800 ÷ (4.5 × 0.8) ≈ 222 W of panels — so two 100W panels or one 200W panel, with a little room to spare. Shading is the silent killer: even partial shade on one panel can cut array output dramatically, so think carefully about roof placement, vents, and awnings.
What Is a Charge Controller?
A charge controller regulates the power flowing from your panels to your batteries so they charge safely and are not overcharged. There are two main types: PWM (simpler and cheaper, fine for small systems) and MPPT (more efficient, often harvesting 10–30% more energy, and the usual choice for arrays above roughly 200–300W or higher-voltage systems). Size it with a safety margin — this calculator adds 25% — and check the manufacturer’s maximum input voltage.
Do I Need an Inverter?
Only if you want to run devices designed for a wall outlet. Many RV essentials — lights, fans, water pumps, USB charging — run happily on 12V DC, and keeping them on DC avoids inverter losses. If you do need AC, size the inverter for the watts you will draw at the same time, plus a margin, and remember motor-driven devices need extra surge capacity. Pure sine wave inverters are the safer choice for sensitive electronics.
Common RV Solar Mistakes
- Underestimating phantom loads. Stereo memory, alarm systems, and “off” appliances quietly drain batteries 24/7.
- Overestimating sun hours. Planning for perfect desert sun while camping under trees leads to disappointment.
- Undersized wiring and missing fuses. Thin wires heat up; every circuit needs proper protection.
- Regularly draining lead-acid batteries below 50%. It dramatically shortens their life.
- Buying panels before measuring the roof. Vents, antennas, and shade can change what actually fits.
- Skipping a battery monitor. Guessing state of charge is stressful; a shunt-based monitor removes the guesswork.
FAQ
Frequently asked questions
Can I run an air conditioner on RV solar?
Usually it is impractical. A typical RV air conditioner draws roughly 1,000–1,800 watts and may run for hours, which can require 10–20+ kWh of battery storage and several kilowatts of solar. Most RVers cool with a generator, shore power, or propane-based solutions, and use solar for lights, fans, and electronics. Try adding the “RV Air Conditioner” preset above — the warnings show you the scale of system it demands.
How many solar panels do I need to charge a 100Ah battery?
As a rough rule of thumb, plan on 200–300 watts of solar for a 100Ah battery bank with 4–5 peak sun hours, depending on battery chemistry and how much energy you actually use. A 100Ah lithium battery stores more usable energy than a 100Ah lead-acid battery, so your real usage matters more than battery size alone.
Is lithium better than AGM for RVs?
Lithium LiFePO4 offers more usable capacity (about 80% vs 50%), longer cycle life, lighter weight, and better charging efficiency, but costs more up front. AGM is cheaper, simple, and fine for light or occasional use. The better choice depends on your budget and how often you camp off-grid.
What is peak sun hours?
Peak sun hours measure the equivalent hours per day when sunlight intensity averages 1,000 watts per square meter. It is not the same as daylight hours — a 14-hour summer day might only deliver 5–6 peak sun hours. Many locations average 3–6 peak sun hours depending on season, latitude, weather, and shading. Use a conservative number for reliable planning.
Do I need a charge controller?
Almost always, yes. Any solar panel large enough to meaningfully charge a battery should go through a charge controller to prevent overcharging and damage. Small trickle/maintainer panels sometimes include built-in regulation, but dedicated PWM or MPPT controllers are standard for RV systems.
What size inverter do I need?
Add up the watts of all AC devices you might run at the same time, then add about a 25% margin. Devices with motors or compressors also need extra surge capacity beyond their running watts. If you only charge USB devices and run 12V appliances, you may not need a large inverter at all.
Can I use a generator with solar?
Yes — solar and generators complement each other well. Solar handles quiet, fuel-free daily charging, while a generator can quickly recharge batteries or power heavy loads like air conditioners and microwaves. Many full-time RVers combine solar, a generator, and shore power.
Is this calculator accurate?
The calculator uses standard sizing formulas, but results are estimates based on the numbers you enter. Real-world results vary with weather, shading, temperature, device duty cycles, and equipment quality. Use the results as a planning starting point, then verify against equipment specifications and, for larger builds, a professional’s advice.
Do I need a professional installer?
Small plug-and-play kits can be DIY-friendly for experienced hobbyists. Larger systems with high currents, big inverter loads, or lithium upgrades involve serious electrical work, fusing, and wire sizing, so consulting a qualified electrician or RV solar installer is strongly recommended. Batteries can deliver dangerous currents, and mistakes can cause fire or damage.
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