🏇 RV & Camper Solar Systems

RV Solar Panel Calculator:
Roof Space Check, 12V DC vs AC Loads, Shore Power

The only RV solar calculator that checks if your panels actually fit on your roof, separates 12V DC from 120V AC loads, and factors in shore power and driving charge so you don’t overbuild your system.

🏘 Design Your RV Solar System

Step 1 — Select Your RV Type
Cab-over design, 25-35 ft. Good roof access. Typical usable roof: 130 sq ft.
Step 2 — Your RV Appliances
Check the appliances you use. Teal = 12V DC (no inverter needed). Orange = 120V AC (needs inverter). Edit watts and hours to match your actual usage.
Appliance Watts Hrs
🔋 Essential 12V DC Loads
⚡ Optional 120V AC Loads (Need Inverter)
Total Daily Load
12V DC: 0 kWh | 120V AC: 0 kWh
— kWh/day
Step 3 — Location and Autonomy
hrs/day
Peak sun hours: Phoenix AZ 6.5 / Las Vegas NV 6.0 / Denver CO 5.1 / Dallas TX 5.2 / Nashville TN 4.7 / Seattle WA 3.8. Most RVers use 4.5 as a safe average.
Step 4 — Components
Step 5 — Charge Sources (Reduces Solar Need)
kWh/day
hrs/day
Shore power: Enter your average daily shore power top-up. If you plug in 3 nights/week at 10 kWh each, that is ~4.3 kWh/day average. Driving charge assumes ~30A alternator output via DC-DC charger.

☀ Your RV Solar System

🏇

Select your RV type, check your appliances, and hit Calculate to get your panel count, battery size, and roof space check.

Why RV Solar Sizing Is Different from Home or Off-Grid Solar

Sizing solar for an RV is not simply a smaller version of sizing solar for a house. The constraints are completely different, and most online calculators miss all of them. Three things make RV solar uniquely challenging: your roof is small, your load is split between 12V DC and 120V AC, and your battery location has to move down the road at 65 mph. Every pound and every inch of roof matters.

The Roof Space Problem Nobody Talks About

A standard 400W solar panel measures roughly 40 inches wide by 70 inches long — that is almost 20 square feet per panel. A typical Class B van conversion has about 65 square feet of usable roof space once you account for the roof vents, AC unit, antennas, and the curved edges where panels would overhang. That means a Class B van can physically fit a maximum of three 400W panels (60 sq ft) before running out of space. If your load calculation says you need 1,200 watts of solar and you have a van, you have a design problem that no charge controller or battery chemistry can solve. Our calculator checks panel count against your specific RV type roof dimensions before anything else.

The 12V DC vs 120V AC Split

This is the single biggest thing RV solar beginners get wrong. Modern RVs are wired as mini-houses with both a 12V DC system and a 120V AC system. The 12V system runs your lights, water pump, vent fans, compressor refrigerator, and slideouts directly from the battery — no inverter involved. The 120V AC system runs your roof air conditioner, microwave, hair dryer, and standard household outlets. AC appliances need an inverter to convert battery DC to 120V AC, and inverters add efficiency losses of 8-12%. If you run only DC loads, you do not need an inverter at all. Most solar calculators lump everything together and always add inverter losses to everything, which both oversizes the battery bank and adds the cost of an inverter you might not need.

How the RV Solar Calculator Works

Our calculator builds your system from the ground up using the specific physics of RV electrical systems. Here is the exact logic:

  • DC loads are drawn directly from the battery. They are sized at 100% of their rated consumption, with only wire and battery efficiency losses applied.
  • AC loads are divided by 0.90 to account for inverter losses (10% efficiency loss for a quality pure sine wave inverter). The battery must supply 11% more energy than the AC appliance actually uses.
  • Shore power offset reduces the net solar requirement. If you average 3 kWh per day of shore power top-up, that is 3 kWh less your panels and batteries need to provide.
  • Driving charge is calculated at approximately 30 amps from a properly installed DC-DC charger (like a Victron Orion-TR Smart 12/12-30) during driving hours. At 12V x 30A = 360 watts, each driving hour adds about 0.36 kWh to your battery, reducing solar and storage requirements.
  • Roof space check converts your panel count into square footage and compares against your RV type’s typical usable roof area, flagging tight or over-capacity scenarios before you buy anything.

Three Real RV Solar Examples

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Weekend Warriors — Class C Motorhome, Southwest Boondocking

Moab UT / Sedona AZ | 5.8 peak sun hours | LFP battery

The Garcias use their Class C on alternate weekends, boondocking in BLM land around Moab and Sedona. They run the basics: compressor fridge, fans, lights, and phone charging. No AC and no microwave — they cook on propane and use the roof vent for cooling.

ApplianceTypeWHrskWh/day
Compressor fridge12V DC45W241.08
LED lights12V DC40W50.20
Vent fans (2x)12V DC70W60.42
Water pump12V DC60W10.06
Devices charging12V DC80W40.32
Total2.08 kWh
At 5.8 sun hours, 2-day autonomy, LFP: 2 x 200W panels (0.4 kW) | 200Ah LFP battery (2.4 kWh usable) | 20A MPPT | No inverter needed (all DC loads). Roof use: 2 panels x 10.5 sq ft = 21 sq ft out of 130 sq ft (16%). Total cost: $1,200-$1,900. The Garcia’s system required no inverter, saving $300-$400 and reducing complexity significantly.
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Full-Time Family Living — Class A Coach, Mixed Campground/Boondocking

Full-time travelers | 4.5 avg peak sun hours | LFP battery

The Kellerman family of four sold their house in Ohio and hit the road full-time in a 40-foot Class A. They plug into shore power 4 nights per week at campgrounds (averaging 8 kWh per hookup) and boondock 3 nights per week. They run the AC unit during hot afternoons and use a microwave daily.

ApplianceTypeWHrskWh/day
Compressor fridge12V DC45W241.08
All 12V DC basics12V DC180Wvarious1.20
Roof A/C120V AC1,500W34.50
Microwave120V AC1,000W0.50.50
Total7.28 kWh
Shore power offset: (4 nights x 8 kWh) / 7 = 4.6 kWh/day average. Net solar need: 7.28 – 4.6 = 2.68 kWh/day. System at 4.5 sun hours, 3-day autonomy, LFP: 4 x 200W panels (0.8 kW) | 400Ah LFP | 40A MPPT | 2,000W pure sine inverter. Roof use: 4 panels x 10.5 sq ft = 42 sq ft of 200 sq ft Class A roof (21%). Total: $6,500-$9,000. Shore power covers most AC load; solar handles the boondocking nights.
🚗

Stealth Van Build — Class B Ford Transit, Pacific Northwest

Portland OR to coastal BC | 3.8 peak sun hours | LFP battery

Graphic designer Mia built a 148-inch Transit High Roof for remote work life. Her roof has two low-profile 100W flexible panels (no rigid mounts needed for stealth), a Victron MPPT, and two 100Ah LFP batteries. She drives 1-2 hours most days, which charges via DC-DC from the alternator.

ApplianceTypeWHrskWh/day
12V fridge12V DC45W241.08
MacBook Pro charging12V DC96W60.58
Monitor + peripherals12V DC60W80.48
Lights + fan12V DC50W40.20
Total2.34 kWh
Driving charge: 1.5 hrs/day x 0.36 kWh = 0.54 kWh/day offset. Net solar: 2.34 – 0.54 = 1.80 kWh/day. At only 3.8 sun hours in the Pacific Northwest: 2 x 100W panels barely covers it (0.2 kW x 3.8 = 0.76 kWh vs 1.80 needed). Mia added a 3rd 100W panel and relies on driving charge and occasional campground plug-ins to fill the gap during winter. Roof check: 3 x 6.8 sq ft = 20.4 sq ft of 65 sq ft van roof — feasible. Total cost: $2,200-$3,200. No inverter needed since everything runs 12V DC, including her laptop via USB-C PD.

Expert Tips for Getting Your RV Solar Right the First Time

1

Run Your RV AC from Solar — Here is the Math Reality

Running a 15,000 BTU RV air conditioner (1,500W) for 6 hours requires 9 kWh per day just for cooling. At 4.5 sun hours, that needs a 2+ kW solar array plus at least 400Ah of LFP battery storage. A Class B van cannot fit this system on its 65 sq ft roof. On a Class C or A, it is possible but expensive — expect $12,000-$18,000 all-in. Most full-timers instead use a Comfort Control or smaller mini-split unit (600-900W) and park in the shade during peak afternoon heat.

2

LFP Batteries Pay for Themselves on the Second Replacement Cycle

A 200Ah AGM bank costs around $350-$450 and lasts 400-600 cycles — about 2-3 years in full-time daily use. A 200Ah LFP bank costs $600-$900 and lasts 3,000+ cycles — 10+ years. After year 3 when the AGM needs replacing, you pay another $400. After year 6, another $400. By year 10 you have spent $1,200 on AGM replacements. The LFP bought in year 1 is still working perfectly. LFP also weighs 60% less per Ah — in a vehicle, that weight savings has real fuel economy value over a decade.

3

Install a DC-DC Charger, Not a Battery-to-Battery Relay

Most RVs come from the factory with a simple battery-to-battery relay (also called a VSR — voltage sensing relay) that connects the house battery to the chassis battery when the engine is running. This is fine for maintaining a charge but delivers only 5-15 amps. A Victron Orion-TR Smart 30A DC-DC charger delivers the full 30 amps the house bank can absorb at its current state of charge — that is 360 watts of free energy every hour you drive. Over a 500-mile travel day (8 hours), that is nearly 3 kWh of recovered energy, equivalent to running a small solar array all day.

16 Frequently Asked Questions About RV Solar Panels

How many solar panels does an RV need?+
It depends entirely on what you run and how much sun you get. A weekend warrior running a 12V fridge, lights, fans, and phone charging in the Southwest needs 1-2 x 200W panels and 200Ah of lithium — roughly a $1,500-$2,500 system. A full-time family running AC and appliances needs 4-6 x 200W panels, 400-600Ah of LFP, and a pure sine inverter — a $10,000-$15,000 system. Use our calculator with your actual appliance list for an accurate answer rather than relying on generic “200W is enough” rules of thumb.
Can I run my RV air conditioner on solar?+
Yes, but it requires a significant system. A standard 15,000 BTU RV AC (1,500W) running 6 hours needs 9 kWh/day from the battery, plus inverter losses. You need at least 1,600-2,000W of solar (8-10 x 200W panels) and 400-600Ah of LFP storage just for the AC, plus additional capacity for all other loads. This is feasible on a Class A or large 5th wheel with 160-200 sq ft of roof, but impossible on a van. Many RVers use a Micro Air EasyStart soft-starter to reduce the AC startup surge, which allows the use of a smaller generator or inverter for the initial startup spike.
What is the difference between a 30-amp and 50-amp shore power connection?+
A 30-amp shore power connection (standard TT-30R receptacle) provides 30A x 120V = 3,600 watts of total power. A 50-amp connection (NEMA 14-50R) provides 50A x 240V across two 120V legs = 12,000 watts total, or 50A x 120V = 6,000 watts per leg. Most Class A and large 5th wheels have 50-amp service so they can run two air conditioners simultaneously. For battery charging: plugging into shore power at either amperage fully charges your house bank overnight through the RV’s built-in converter/charger, typically delivering 30-100A depending on the converter’s rating. A quality aftermarket charger like a Victron MultiPlus-II can charge at up to 120A when on 50-amp service.
Should I use flexible or rigid solar panels for my RV?+
Rigid panels (monocrystalline or polycrystalline in aluminum frames) are more efficient, last 25+ years, and cost less per watt. They require tilting brackets or fixed mounts 1-2 inches above the roof for airflow, which is critical — a panel at 150F loses 25% of its rated output. Flexible panels are thinner and lighter, conforming to curved roofs, making them popular for vans where stealth or aerodynamics matter. However, most flexible panels have a 5-year warranty versus 25 years for rigid, degrade faster due to no airflow underneath, and cost more per watt. Best advice: use rigid panels with Z-brackets or tilt mounts where roof shape allows; use flexible only where rigid physically will not fit.
What size MPPT charge controller do I need?+
MPPT controller size is determined by two limits: (1) max charge current to the battery, and (2) max solar input wattage. For battery current: divide total panel watts by battery voltage, then multiply by 1.25 for NEC safety. Two 200W panels at 12V: 400W / 12V x 1.25 = 41.7A — requires a 40A or 60A MPPT. For solar input voltage: check the controller’s PV input voltage limit (usually 100V or 150V Voc). Never wire panels in series if the combined open-circuit voltage exceeds the controller’s limit; in cold weather, Voc can be 10-15% higher than the spec sheet rated voltage. Our calculator handles this sizing automatically and recommends standard Victron or Renogy controller sizes.
Do I need a pure sine wave inverter or will a modified sine wave work?+
Modified sine wave inverters (MSW) are cheaper but cause problems in RVs: they make a loud audible buzz through speakers and TV audio; they cause some microwave models to run at reduced power; they can damage or not operate CPAP machines (most CPAP manufacturers explicitly require pure sine wave); and they run motors (AC units, water heaters with motors) hotter and less efficiently, shortening their lifespan. For any permanent RV installation, only use a pure sine wave inverter. The cost difference between MSW and PSW at 2,000W is typically $100-$200 — completely worth it.
How does the alternator charge my RV batteries while driving?+
In most factory RVs, the house battery connects to the chassis (starter) battery through a battery isolator or VSR that only allows current to flow when the engine is running and the chassis battery is fully charged. This is highly inefficient for LFP house batteries because LFP holds a high charge acceptance voltage that confuses simple voltage-sensing relays into cutting off the connection early. A proper DC-to-DC charger (like the Victron Orion-TR Smart or Renogy DCC50S) eliminates this problem by actively controlling the charge current from alternator to LFP, delivering a true 20-50A depending on the charger model. At 30A and 12V, you are producing 360 watts of charge — equivalent to two 200W solar panels in full sun.
What is a reasonable RV solar budget?+
Entry-level systems for weekend warriors (2 x 200W panels, 200Ah LFP, 20A MPPT): $1,200-$2,000 DIY or $2,500-$3,500 professionally installed. Mid-range full-timer systems (4 x 200W panels, 400Ah LFP, 40A MPPT, 2,000W inverter): $5,000-$8,000 DIY or $9,000-$14,000 installed. Premium Class A systems with roof AC capability (8 x 200W panels, 600Ah LFP, 80A MPPT, 3,000W inverter): $12,000-$18,000 DIY. Labor for professional installation typically runs $75-$150/hour and adds $1,500-$4,000 to a typical system. DIY installation is the most popular route for RVers because the wiring is accessible and the systems are modular.
Can I use my RV solar system while plugged into shore power?+
Yes — in fact, this is the ideal configuration. With an inverter-charger (like a Victron MultiPlus), the system automatically uses shore power for heavy loads and supplements from solar and battery when the sun is shining. When plugged in, the shore power charges the batteries and runs the loads while solar reduces the amount of shore power consumed. When you unplug, the system seamlessly switches to battery power. This “hybrid” mode is how most full-timers operate and is the reason good solar/battery systems dramatically reduce campground electrical fees even on nights when they plug in.
What is the best battery chemistry for RV use?+
LFP (Lithium Iron Phosphate) is the clear winner for most RVers in 2024-2025 for four reasons: weight (a 200Ah LFP is about 56 lbs vs 130 lbs for equivalent AGM capacity at 50% DoD), lifespan (3,000-6,000 cycles vs 400-600 for AGM), usable capacity (90% vs 50%), and maintenance (zero vs regular equalization and watering for flooded lead-acid). The higher upfront cost ($600-$900 for 200Ah LFP vs $350-$450 for 200Ah AGM) is recovered in 3-4 years through eliminated replacements and the weight savings from needing fewer cells. The one scenario where AGM wins: extremely cold storage, as LFP should not be charged below 32F without a built-in Battery Management System (BMS) with low-temperature cutoff.
How do I mount solar panels on my RV roof?+
Z-brackets are the most popular low-profile mounting option, attaching directly to the panel frame and the roof at four points per panel. They typically raise the panel 1-2 inches off the roof — enough airflow to prevent excessive heat buildup. The mounting points must be drilled and sealed with Dicor lap sealant or similar self-leveling sealant rated for your roof type (TPO, EPDM, or fiberglass). Tilt mount brackets allow adjusting the panel angle seasonally, increasing winter production by 15-25% in northern states. Some RVers use no-drill VHB tape mounting for flexible panels, but this is not recommended for permanent installations in areas that see freezing temperatures or freeway speeds.
What wire gauge do I need for my RV solar installation?+
Wire sizing depends on amperage and run length. Panels to controller: calculate amps as (panel watts / system voltage) x 1.25 safety factor; typical runs require 10-12 AWG. Controller to battery: use the controller’s rated amps to size the wire; a 40A MPPT running 3 feet to the battery needs 8 AWG minimum. Battery to inverter: this is the highest current run; a 2,000W inverter at 12V draws 167A continuously, requiring 2/0 AWG for runs under 3 feet. Use marine-grade tinned copper wire for RV applications — it resists corrosion and vibration far better than standard residential wire. All positive conductors must be fused within 18 inches of the positive battery terminal as required by the NEC and NFPA 70.
How many peak sun hours does my travel route average?+
Peak sun hours vary dramatically by location and season. The American Southwest (AZ, NV, NM, Southern CA) averages 5.5-7 peak sun hours annually — the best RV solar territory in the country. The Southeast (FL, GA, TX) averages 4.5-5.5. The Mountain West (CO, WY, UT) averages 4.5-5.5. The Pacific Northwest and Upper Midwest average 3.5-4.5 with significant winter drops. Many full-timers plan their routes around sun — “solar snowbirds” who head southwest for winter are consciously optimizing their solar production. For a mixed-route annual average, 4.5 peak sun hours is a reasonable planning figure for most of the continental US. Use NREL’s PVWatts tool at pvwatts.nrel.gov for your specific locations.
Do RV solar systems qualify for the federal 30% tax credit?+
Yes, with important caveats. The Residential Clean Energy Credit under the IRA 2022 provides a 30% tax credit for solar and battery storage systems that power a dwelling. An RV qualifies if it is your primary or secondary residence — which covers full-time RVers and many part-time users. The credit applies to panels, batteries, inverter, charge controller, wiring, and labor if professionally installed. It does not apply to RVs used purely for recreational purposes with no residential qualification. Consult a tax professional for your specific situation and review current IRS guidance as eligibility rules can change.
How do I protect my solar system from damage while driving?+
The biggest risks while driving are vibration stress on connections and overheating from no airflow when the vehicle is moving. For connections: use ring terminals properly crimped (not twisted) onto wire ends, and use thread-locking compound on all bolts in terminal blocks. For panels: ensure all mounting screws are tightened to spec and re-checked after the first 500 miles. The vibration from highway driving will loosen everything initially. For the MPPT controller and inverter: mount them in ventilated compartments with airflow; these components generate significant heat under load and need at least 2 inches of clearance on all sides. Never mount electronics in airtight compartments.
What monitoring should I install for my RV solar system?+
A battery monitor (shunt-based) is the most important display. It tells you state of charge, amps in/out, and estimated hours remaining — exactly like a fuel gauge for your battery bank. The Victron BMV-712 ($80-$100) is the gold standard for DIY installs. If you use a Victron MPPT controller, their Bluetooth app shows real-time solar production and battery status from your phone. Many RVers also install a Victron Cerbo GX as a central monitoring hub that tracks solar, battery, inverter, and shore power simultaneously on a single touchscreen display or remote app. Monitoring matters because without it, you are guessing at your power situation — and guessing wrong usually means a dead battery in the morning.

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Legal Disclaimer and Editorial Transparency

The RV Solar Panel Calculator on USCalculators.com provides estimates for educational and planning purposes only. All outputs are based on standard solar engineering sizing methodologies and the appliance data and preferences you provide. Actual system performance depends on your specific RV model and roof dimensions, real-world appliance consumption patterns, installation quality, local climate, shading from trees and structures, and panel orientation and tilt.

Roof space estimates are based on typical usable area for each RV category and will vary with your specific rig’s roof obstructions (AC units, vents, antennas, satellite dishes). Always measure your actual available roof space before purchasing panels. Weight estimates assume standard 100Ah battery cell dimensions and may vary by manufacturer.

Cost estimates reflect typical US retail pricing for mid-range components and do not include installation labor (typically $75-$150 per hour, $1,500-$4,000 for a typical system). The 30% federal tax credit applies to qualifying residential uses — see IRS.gov and consult a qualified tax professional for eligibility. All electrical work should comply with NEC Article 551 (RV Electrical Standards) and applicable state codes.

Editorial policy: USCalculators.com is an independent educational resource. We do not accept payment for product recommendations and have no affiliate relationships with solar equipment manufacturers or RV solar installers.