How Much Solar Do I Need for My RV? (2026 Sizing Guide)

01The short answer: typical ranges

If you want a starting point before doing the math, here is where most RVers land. Treat these as rough brackets, then use the five steps below to pin down your number.

Battery figures assume one day of autonomy at 12V nominal. The worked examples in section 07 show exactly how these numbers are derived, so you can adjust them to your own usage instead of trusting a table.

02Step 1: Add up your daily watt-hours

Everything starts here. For each appliance, multiply its power draw (watts) by the hours you run it per day. That gives watt-hours (Wh), the unit every other step uses.

Daily energy (Wh) = watts × hours per day

The table below uses typical values for planning. Your models will differ, so check nameplates and manuals for the big loads (fridge, microwave, air conditioner). Values marked "effective" account for the fact that fridges and pumps cycle on and off rather than running constantly.

Two things people forget at this step. First, inverter losses: anything running on 120V AC (laptop, TV, microwave) costs extra because the inverter is not perfectly efficient. As a planning estimate, multiply AC loads by 1.15 when converting to battery-side watt-hours; actual inverter efficiency varies by model and load, so treat 15 percent as an estimate, not a specification. Second, phantom and standby loads: stereos, control boards, and chargers left plugged in sip power all day. They rarely change the answer much, but they explain why real usage often runs a little higher than the spreadsheet.

If the math feels tedious, the RV solar calculator on this site does the same arithmetic with your own inputs.

03Step 2: Find your peak sun hours

A peak sun hour is one hour of full 1,000 W/m2 sunlight. Five peak sun hours does not mean five hours of daylight; it is the equivalent energy of a full day compressed into perfect-sun hours. A bright eight-hour day with haze, morning shade, and a low sun angle might only deliver four or five peak sun hours.

Do not guess this number. Look it up for your actual camping locations with a free tool:

• NREL PVWatts: enter a location and it reports monthly solar radiation data you can convert to peak sun hours.
• Global Solar Atlas: click any spot on the map for solar resource figures.

As clearly labeled rough examples for planning (verify your own location with the tools above): the desert Southwest runs about 5.5 to 6.5 peak sun hours in summer, the Southeast and Midwest sit around 4 to 5.5 for much of the year, and the Pacific Northwest can drop to 1.5 to 2.5 in winter. Season matters as much as region. Size for the season you actually camp in, which section 08 and the FAQs come back to.

04Step 3: Size the panel array

Now divide your daily watt-hours by the energy one watt of panel delivers in your location:

Panel watts = daily Wh ÷ (peak sun hours × 0.75)

The 0.75 is a system performance factor for planning. It accounts for the panel running hotter than lab conditions, imperfect roof angle, dust, wiring losses, and controller conversion losses. A range of 0.70 to 0.80 is reasonable; 0.75 sits in the middle. It is a planning allowance, not a measured specification.

Example: 1,000 Wh per day ÷ (5 peak sun hours × 0.75) = 1,000 ÷ 3.75 = about 267W. Round up to standard panel sizes and you land at roughly 300W of panels. Rounding up is deliberate: a little headroom covers the days that underperform the average, and an array slightly larger than the minimum also recharges the bank faster after cloudy stretches.

One more check belongs here: roof space. Watts on paper mean nothing if the panels do not fit around your vents and air conditioner. Measure usable roof rectangles before buying, as the mounting guide explains. If roof space caps you below the calculated wattage, that is useful information: it tells you to trim usage, add portable panels, or plan generator backup rather than hoping the math works out.

05Step 4: Size the battery bank

Panels make power by day; the battery bank is what carries you through the night and cloudy stretches. Size it from your daily watt-hours and the number of low-sun days you want to ride through (days of autonomy). One day suits weekenders who can drive home; two to three suits boondockers who need weather margin.

Usable Ah needed = (daily Wh × autonomy days) ÷ 12V

All calculations in this guide assume a 12V nominal system, the standard for most RV house batteries. If your system is 24V or another voltage, adjust the amp-hour math accordingly (usable Ah = daily Wh divided by your system voltage). Then convert usable amp-hours to the nominal battery size you actually buy, because chemistries differ in how deeply they can be discharged:

• Lithium (LiFePO4): typically 80 to 100 percent usable, but always go by the battery manufacturer's specification and operating limits. Some batteries restrict usable capacity, and most prohibit charging below freezing unless they include low-temperature protection.
• Lead-acid (flooded or AGM): about 50 percent usable if you want reasonable cycle life. Regularly draining lead-acid below half shortens its life significantly.

Nominal Ah to buy = usable Ah ÷ usable fraction

Example: 1,000 Wh/day, one day of autonomy, 12V nominal → 1,000 ÷ 12 = 83.3 Ah usable. Lithium at 90 percent usable: 83.3 ÷ 0.90 = 92.6 Ah, so a single 100 Ah lithium battery. Lead-acid at 50 percent: 83.3 ÷ 0.50 = 166.7 Ah, so 200 Ah of lead-acid (for example, two 100 Ah batteries in parallel). Double everything for two days of autonomy.

06Step 5: Size the controller and inverter

Charge controller

The controller sits between the panels and the batteries. MPPT controllers convert the panels' higher voltage into extra charging current, which makes them the better fit for most RV arrays, especially larger ones or panels wired in series. PWM controllers cost less and can suit very small arrays where the panel voltage closely matches the battery voltage, but they harvest less energy from the same panels. Either way, size from the array wattage at your battery voltage:

Controller amps ≈ array watts ÷ 14.4V (typical charging voltage on a 12V nominal system)

Then shortlist a controller at or above that current with some headroom, and confirm every one of these limits in the controller's manual before buying. Moving up one nominal size does not by itself make a controller compatible: a 300W array ÷ 14.4V = 20.8A, so a 30A MPPT controller is a reasonable starting point if its manual confirms the limits below. An 800W array ÷ 14.4V = 55.6A, so start from a 60A MPPT (or two smaller controllers) and verify the same way.

• Maximum PV open-circuit voltage, including cold-weather voltage rise
• Maximum PV short-circuit current or other PV input-current limits
• Maximum permitted array power at your battery voltage
• Maximum battery charging current
• Supported battery chemistries and charging profiles

The watts-divided-by-volts figure is an approximate charging-current estimate for shortlisting, not a complete controller selection method.

Inverter

You only need an inverter for 120V AC appliances. Add up the AC loads you will run at the same time, then pick a pure sine wave inverter whose continuous rating covers that total with margin, and whose surge rating covers the largest startup spike. Check both numbers in the appliance and inverter manuals rather than assuming.

Example: a 1,000W microwave plus 200W of other AC loads running together = 1,200W continuous, so the inverter's continuous rating must exceed 1,200W, and its surge rating must cover the largest startup spike among those appliances. A 2,000W pure sine wave inverter is a common choice for this load, but confirm both the continuous and surge ratings against your actual appliance specifications rather than assuming headroom. If all you run is a laptop and phone chargers, a small 300 to 600W inverter (or 12V chargers that skip the inverter entirely) is plenty.

07Two worked examples with full math

Both examples assume 5 peak sun hours, a 0.75 system factor, and a 12V nominal system. Every step is shown so you can substitute your own numbers.

Example A: weekend camper, about 1,000 Wh/day

Daily loads (DC side):

• LED lights (6 × 8W × 4h) = 192 Wh
• 12V compressor fridge (50W × 9h effective) = 450 Wh
• Vent fan (25W × 6h) = 150 Wh
• Water pump (70W × 0.5h) = 35 Wh
• Phone charging (15W × 3h) = 45 Wh
• DC subtotal = 192 + 450 + 150 + 35 + 45 = 872 Wh

Daily loads (AC side, through inverter):

• Laptop (60W × 2h) = 120 Wh at the device
• Inverter loss, approx 15% = 120 × 0.15 = 18 Wh
• Battery-side AC = 120 + 18 = 138 Wh

Daily total = 872 + 138 = 1,010 Wh (call it 1,000 Wh for planning).

• Panels: 1,010 ÷ (5 × 0.75) = 1,010 ÷ 3.75 = 269W → round up to 300W of panels (for example, three 100W panels, or a single larger panel; see the 435W panel guide for the one-large-versus-several-small trade-off).
• Battery (1 day autonomy): 1,010 ÷ 12 = 84.2 Ah usable → lithium: 84.2 ÷ 0.90 = 93.6 Ah → 100 Ah lithium; lead-acid: 84.2 ÷ 0.50 = 168.4 Ah → 200 Ah lead-acid.
• Controller: 300 ÷ 14.4 = 20.8A → 30A MPPT.
• Inverter: laptop and phones only → a small 300 to 600W pure sine wave inverter, or 12V chargers with no inverter at all.

Example B: full-timer, about 3,000 Wh/day

Daily loads (DC side):

• 12V compressor fridge (50W × 10h effective) = 500 Wh
• LED lights (8 × 8W × 5h) = 320 Wh
• Vent fans (2 × 25W × 8h) = 400 Wh
• Water pump (70W × 1h) = 70 Wh
• Phone/tablet charging (20W × 4h) = 80 Wh
• DC subtotal = 500 + 320 + 400 + 70 + 80 = 1,370 Wh

Daily loads (AC side, through inverter):

• Laptop (65W × 4h) = 260 Wh
• LED TV (40W × 3h) = 120 Wh
• Microwave (1,000W × 0.25h) = 250 Wh
• Coffee maker (800W × 0.3h) = 240 Wh
• Starlink/router (40W × 10h) = 400 Wh
• AC subtotal at the devices = 260 + 120 + 250 + 240 + 400 = 1,270 Wh
• Inverter loss, approx 15% = 1,270 × 0.15 = 190.5 Wh (round to 190)
• Battery-side AC = 1,270 + 190 = 1,460 Wh

Daily total = 1,370 + 1,460 = 2,830 Wh, rounded up to 3,000 Wh for planning margin.

• Panels: 3,000 ÷ (5 × 0.75) = 3,000 ÷ 3.75 = 800W of panels.
• Battery (1 day autonomy): 3,000 ÷ 12 = 250 Ah usable → lithium: 250 ÷ 0.90 = 277.8 Ah → 300 Ah lithium; lead-acid: 250 ÷ 0.50 = 500 Ah → 500 Ah lead-acid. Double for two cloudy days.
• Controller: 800 ÷ 14.4 = 55.6A → 60A MPPT (or two smaller controllers).
• Inverter: microwave (1,000W) plus typical simultaneous loads ≈ 1,200W continuous → 2,000W pure sine wave inverter with surge headroom. Verify surge ratings in the manuals.

Notice the pattern: doubling daily use roughly doubles every component. That is why the appliance audit in step 1 matters more than any rule of thumb. If these numbers look like your usage, the 1000W solar kit guide and the 600W panel guide show what complete systems at this scale look like.

08Mistakes that leave RVers short on power

• Sizing panels but starving the battery. The most common error. Once the bank is full, the controller tapers charging and extra midday production goes unused; then a small bank can run out of usable energy overnight while loads keep drawing. Size the battery first in your head, then the panels to refill it.
• Counting rated watts as real watts. A 400W array does not deliver 400W all day. Heat, angle, dust, and wiring losses take their cut, which is exactly what the 0.75 factor in step 3 accounts for.
• Forgetting inverter losses. Every AC watt-hour costs about 15 percent extra at the battery. On microwave-and-coffee-maker setups this adds up to hundreds of Wh per day.
• Ignoring startup surge. Motors and compressors briefly draw several times their running watts. An inverter that covers running watts but not surge will shut down the moment the load kicks on.
• Sizing for July and camping in January. Winter sun can be a third of summer sun in northern states. Size for your actual camping season or carry a generator for the shortfall.
• Mixing old and new batteries. Adding fresh batteries to an aged bank typically gives you the performance of the old ones and shortens the life of the new ones. Battery manufacturers generally recommend replacing banks as a matched set; check your battery manual.
• Skipping the controller math. Array watts alone do not size a controller. Check max PV voltage (with cold-weather margin), max PV current, and max PV power at your battery voltage in the manual.
• Assuming the sidewall port handles everything. Factory solar ports (often labeled Solar On The Side) are convenient for portable panels but have wiring and fuse limits set by the RV maker. Read how the port actually works before plugging a big array into it.

★The bottom line

Do the five steps with your own numbers and you will land on the right size the first time: audit your appliances, look up peak sun hours for your actual camping spots, divide daily Wh by (sun hours × 0.75) for panels, divide daily Wh by 12V and your chemistry's usable fraction for batteries, then size the controller and inverter from the array and the loads. As rough brackets, weekenders often land at 200 to 400W of panels with 100 Ah of lithium, and full-timers at 800W or more with 300 Ah, but your numbers decide, not the brackets.

If you are between two sizes, put the money into the battery bank first. Extra panel watts only help when the sun is out, but extra usable amp-hours help every single night. And before you buy anything, run your numbers through the RV solar calculator, then look at complete systems in the 600W and 1000W kit guides to see what your target size looks like as real hardware.