As you’re driving down the highway, sunlight pouring down on the roof of your RV, adding solar power seems like a no-brainer!
Here are a few reasons why solar power can be a great addition to your RV experience:
Freedom: You can choose off-the-beaten-path locations.
Quiet: Solar is virtually soundless.
Ease: Solar requires no fuel and little maintenance.
Green Merit Badge: Reduce your carbon emissions.
Cost: Save money!
Although running solar can save you money, purchasing and installing a solar power system sufficient to meet your needs can be expensive, meaning cost-savings follow only after years of use.
For camp hookups, a gasoline-powered generator makes more financial sense than solar: Hookup fees for occasional outings are not significant, and it would take years to recoup your investment in a solar power system.
Hookup fees can be a significant expense for boondockers. These RVers also are more likely to seek out dry camps and locations that lack hookups. A solar power system, even with a small generator as a backup power source, is an investment that can amortize in 2 to 4 years.
Park campsite rental fees include shoreline power. A solar power system would be redundant and not a cost-saving measure.
How do you know whether it makes financial sense to go solar? Look at the basic costs involved for three categories of RVers: weekend warriors, who RV occasionally for vacations and weekend getaways; boondockers, who spend extended periods at campsites and dry camping; and full-timers, who spend the majority of their time at campsites. This chart is based on an average campsite hookup fee of $40 per night.
How do you know if a solar power system makes financial sense? This guide will help you understand all the costs involved in an RV solar power system.
Does an RV Solar Power System Make Sense for You?
A solar power generating system is made up of solar panels and batteries, plus monitoring and controlling devices. The more solar panels and batteries you have, the more appliances you can power. Once you know how much power you typically use, you can estimate the costs of powering some, or all, of your appliances and devices.
The Math of Energy Consumption
This chart is a quick gauge as to whether solar power makes sense for an RVer, based on lifestyle categories. For a more in-depth look, examine your own power consumption. Determine how much power your individual appliances consume. It is possible to use solar to power a portion, but not all, of your appliances.
Typical Power Consumption per Day, in Watt-Hours/Day
Below are typical daily power consumption figures for some popular RV appliances: a 19” LCD TV, a 13” laptop, four lamps, a water pump, two fans, a 1000-watt microwave, and an under-the-counter refrigerator. While this chart provides common usage amounts, you should develop your own list tailored to your personal power consumption levels.
Samples of RV Appliance Energy Use
Hours of daily use
Note that a refrigerator is an energy hog, representing more than 70 percent of power consumption, with the remaining appliances using 1,770 watts a day.
In doing your calculations, also figure in appliances you use only occasionally, such as a vacuum cleaner or hairdryer. And note that all appliances continue to draw small amounts of power even when not actively being used, so you’ll need to add a margin of capacity for sleep mode.
Basic Parts of an RV Solar Power System
Solar energy for an RV can come in a number of configurations, particularly if you are a do-it-yourselfer. A 400-watt starter kit suitable for the roof of a standard RV might consist of four solar panels with wiring and an attached controller. You’ll also need batteries, a battery monitor and an inverter, which changes the DC power stored in the batteries into AC power for your appliances.
Solar panels are generally similar in finished size, but the materials used in their solar cells can differ. The most popular solar cell material is crystalline silicon, makes up the two most popular types of solar cells:
1) Polycrystalline—most popular, best price
2) Monocrystalline—more efficient, higher price
Another type of solar cell is a thin-film solar cell (TFSC), which looks great and can be made into flexible shapes, but currently is less efficient than crystalline silicon.
A charge controller sits between an energy source (panels) and energy storage (batteries). The controller prevents overcharging by limiting the amount and rate of charge to your batteries and protects against drainage by shutting down if stored power falls below 50 percent capacity.
Maximum Power Point Tracking (MPPT) controllers go a step further by optimizing the conversion of solar energy into the best voltage for your particular batteries, providing more and better power generation.
The inverter turns the low-wattage DC power produced by solar panels and stored in batteries into AC power, which is the type of power used by most appliances.
Most RVs have at least one 12-volt, lead-acid battery. For solar, add three more in parallel to provide 280–340 amp-hours (AH) of capacity. Alternatively, you could use 6-volt, golf-cart-style batteries; four of these, set up in series, provide 440 AH of capacity. Lithium-ion batteries are more expensive but are more efficient in storing energy, and they weigh half as much as lead-acid batteries.
How Much Do Solar Panels for RVs Cost?
A 400-watt system gathering sunlight for five hours a day can theoretically generate 2,000 watts. In reality, few days are 100 percent sunny, and few systems are 100 percent efficient, but a 400-watt system can generate enough energy for daily appliance use for weekend warriors and boondockers.
As a practical matter, a system of 800 watts or more is ideal for an RVer, particularly if you are boondocking. You’ll generate twice the wattage, up to 4,000 watts, which is sufficient to run the majority of your appliances. Doubling the wattage will require four additional panels and one or two additional batteries, but your converter and inverter remain the same. The net additional cost might be $800 to $1,200.
You can buy solar panels at home improvement stores and online at Amazon, eBay and a number of other websites. Solar power systems are often sold in kits, which include panels plus a system monitor, wiring and connectors. Kits may or may not include mounting gear, controller and inverter — check kit contents carefully, as you will need all these components.
Note: Pricing does not include installation. Some kits include wire, connectors, and inverter. Most kits include a 30-amp charge controller, which is excessive for small systems but gives you the option to add panels in the future without buying a new controller.
The Math of RV Solar Energy Savings
When describing the energy savings of going solar, it’s usually in terms of how much you’re saving when compared to what you would spend generating power with a gas generator. An average generator burns one half-gallon of gas an hour; the average price of a gallon of gas in the U.S. is $2.25. If you are parked at a site and use a gas generator for four hours, you’ll spend $5 on gas.
Based on that figure, if you had a $3,900 investment in solar instead, you would reach a break-even point on your investment in 780 days, which is 2.14 years of daily use. If solar allows you to avoid $40-a-night campground fees, your break-even point arrives much sooner.
After you reach the break-even point with solar, your energy costs from then on would be $0, other than what you’d pay for any replacement parts. For instance, your batteries would need to be replaced after about five years of use.
In reality, even if you have a good-sized solar energy rig, you likely will use a gas generator from time to time, particularly during rainy or cloudy periods, in order to maintain a charge in your batteries. You may also want a generator capable of running an air conditioning unit, as it’s nearly impossible to run this energy-guzzling appliance on solar.
RV Batteries for Solar: Old vs. New Battery Technology
If solar panels are your power-generating source, batteries are your power storage center. An RV typically has at least one 12-volt battery, but you will need more; the number you need would be based on the amount of power you are generating from your solar panels. There are three major battery technologies readily available on the market, and each has its pros and cons.
Use a deep-charge battery suitable for RV or marine use.
Available everywhere at big-box and auto parts stores.
Reliable, well-understood technology
Inexpensive per amp-hour in comparison to AGM and lithium-ion
Draining batteries to
< 50 percent shortens the lifetime.
Lifetime of use, measured in “life cycles,” is typically between 500 and 1,000 cycles.
Spilled battery acid can burn skin and surrounding surfaces.
Require periodic maintenance.
Absorbed Glass Mat battery technology uses plates, just like lead-acid batteries, but it adds a slim fiberglass mat saturated with battery acid between the plates and packs these internal components tightly.
Tough and virtually immune to vibration.
Efficient in storing energy, storing 10 to 15 percent more than lead-acid batteries.
Charge up to four times faster than lead-acid batteries.
No danger of spills.
Require no maintenance.
Much more expensive than lead-acid batteries.
Lithium-ion batteries work on a different principle and use different chemicals than lead-acid and AGM batteries. Common in laptop computers, cell phones and electric cars due to their lightweight and other factors.
Live up to four times longer than lead-acid batteries in similar use. Maintenance-free, sealed, waterproof housings.
Can perform at low temperatures.
Weigh less than half of similar capacity lead-acid and AGM batteries.
Expensive relative to other battery technologies.
How to Decide Which Battery Technology to Use
The cost differences among battery types are dramatic, but so are the differences in performance. Simply stated, do you buy the cheap but highly standard battery and change it out every two years, or do you get a higher performance unit that will last up to eight years?
The truth is, you can’t really go wrong either way. If you choose the cheaper route, you can always upgrade in a couple of years, and any extra money might be better spent on more solar panels.
Sampling of Batteries Suitable for RVs
Labeled Capacity @C1
Size (inches) Length x Width x Height)
Walmart EverStart Maxx
11 x 6.6 x 9
Trojan Reliant T1275-AGM
13 x 7 x 11
12.8 x 6.5 x 8.7
Can I Run My Air Conditioner on Solar?
When you’re considering the economics of solar, it’s best to approach it in progressive steps:
Purchase a system large enough to run most appliances — 2,000 to 2,500 watts per day.
For financial and environmental reasons, this first step will make you happy. It will cost $3,500 to $4,500, and you’ll recoup that investment in two to four years, depending on your RV use. You’ll run your fridge off a generator-charged battery.
Add enough capacity to run a refrigerator all day — 4800 watts/day, for a system total of 6,800 to 7,300 watts per day.
This step will make you even happier. Spend an additional $1,200 for four solar panels and two more batteries and you can keep your food cold with solar. Meanwhile, your generator will remain quiet, except on rainy days.
Add enough to run an air conditioning unit — 14,400 watts per day, for a system total of 21,200 to 21,700 watts per day.
Unfortunately, this step is nearly impossible. Even if you can afford an additional $4,800 in panels and batteries, you’ll run out of room on your roof, so you’ll need to tow a trailer with additional panels and batteries.
Our advice? If you need AC, visit a campsite and plug in.
“Absorbed Glass Mat” battery technology uses plates, as with lead-acid batteries, but AGM features a slim fiberglass mat saturated with battery acid between the plates and packs these internal components tightly.
A charge controller limits the amount and rate of power to prevent battery overcharging, and it shuts off the batteries if stored power falls below 50 percent to avoid draining. A Maximum Power Point Tracking (MPPT) controller goes a step further by optimizing the conversion of solar energy in order to produce the best voltage for your batteries.
Lead-acid batteries rely on a chemical reaction between chemicals and water to store energy. This internal process occurs between plates sealed inside the battery. Lead-acid batteries are mass-produced for cars, trucks, RVs and other vehicles, so prices for these are much less than those for other battery technologies.
Lithium-ion batteries use a different technology than traditional lead-acid or AGM batteries: They have chemicals that use one process for storing energy and an opposite process when distributing it; they continue to cycle back and forth, giving the battery a much longer life than traditional batteries.
Modified Sine Wave
The technology of measuring the voltage passing from a DC power source (solar panel or battery) through an inverter was initially done in small sample batches, creating a series of stair steps that represent the continuous rise and fall of charge. To make the representation more easily understood, modified sine wave measurements commonly average out sampled voltage values to create a visual that resembles a sine wave.
Every panel type reflects the manufacturing technology of its core component, the solar cell. Crystalline silicon-based cells are used in polycrystalline and monocrystalline panels; multilayered, nonsilicon cells are used to create thin-film solar cells.
Pure Sine Wave
A sine wave is a visual indication of electricity transmission on an oscilloscope, such as the voltage transmitted from your DC-power battery or solar panel through an inverter to make AC voltage. Ideally, the sampling of voltage in transit would be continuous and reveal a series of smooth waves.
RV Solar Resources
altE: altE is an online blog with solar information for RVers, with the motto of “Making Renewable Do-Able.” The site offers good tips with a folksy touch, including homemade drawings, and it promotes certain brands, so make sure to comparison shop.
Energy Informative: An online solar information site sponsored by the solar industry. Find clear definitions of terms and descriptions of components and the technology behind them.
Northern Arizona Wind & Sun: This online source for solar information was developed by a family-owned solar installation business, and it includes a full section for RVers. The site promotes certain brands, so be sure to comparison shop.
RV Solar Made Simple: Roads Less Traveled is an online site recounting the adventures of a husband and wife who are full-time RVers. This page, “RV Solar Made Simple,” describes what they’ve learned solar power for RVs. The site promotes certain brands, so be sure to comparison shop.
Technomadia: A couple who have been on the RV road since 2006 share tales and tips on this site, including their transition from a small solar power system to going totally solar.