- How Solar Panels Are Rated
- Average Energy Needs for an RV
- How Temperature Affects Solar Panel Efficiency
- Optimizing Panel Orientation
- Comparing Panel Types
- Additional Ways to Maximize Solar Output
- Solar Performance Examples
- Sizing Your Solar System
- Helpful Products to Maximize Solar Output
- Creative Solutions for Shady Situations
- Cool Solutions for Hot Climates
- Bright Ideas for Gloomy Weather
- Solar Tracking for Optimal Orientation
- Knowing When to Go Bigger
- Great Solar Options for Small RVs
- Solar Loans – Financing Your RV Solar System
- Buying Used Solar Panels and Equipment
- Common Solar Myths and Misconceptions
- Ways to Get Started with Solar
Solar power output depends on several factors. Understanding how your solar panel rating correlates with real-world energy production will help you get the most from your system.
How Solar Panels Are Rated
Manufacturers rate solar panels in watts to indicate how much power they can produce in ideal test conditions. This “peak wattage” represents the maximum potential output, not the actual amount you’ll get day-to-day. Test conditions include pointing panels directly at midday sun and operating at 77°F. Real-world conditions are seldom ideal, so panels rarely achieve their full rated wattage.
For RVs, typical solar panel ratings range from 100W to 400W. But a 400W panel won’t necessarily produce 400 watts of continuous energy. The panel rating merely indicates the maximum output if pointed at unobstructed noonday sun. Early morning, evening, and cloudy days will see significantly lower production.
Average Energy Needs for an RV
When solar powering an RV, a common rule of thumb is to estimate needing about 10 to 20 watts per square foot of RV roof space. For example, an RV with 100 square feet of roof space would need a solar system producing 1,000 to 2,000 watts.
Another approach is estimating average daily power needs. A typical RV with basic lighting, appliances, and electronics requires about 3 to 5kWh per day. With 6 hours of peak sun per day, an average 400W solar panel system could meet these needs. For constant refrigerator, computer, and device charging, a larger system up to 800W to 1,200W may be preferable.
Understanding your RV’s electrical requirements will help determine your ideal panel wattage. Monitor your current usage to estimate an average daily power need. Then allow for future additions like a microwave or air conditioner. A flexible, expandable solar system will grow with your RV lifestyle.
How Temperature Affects Solar Panel Efficiency
A solar cell’s temperature directly impacts its voltage and efficiency. In essence, solar panels work more efficiently in cooler weather. Colder temperatures allow panels to produce higher voltage. But in very hot weather, high temperatures make panels less efficient.
Most solar panels reach optimal efficiency around 77°F. Their rated power drops linearly as temperatures increase. Expect decreased output above 77°F on hot sunny days.
For example, a typical panel may produce only 80% of its rated power at 95°F. At 113°F, energy production could decrease to 70% of the rated wattage. desert conditions could see even greater efficiency losses.
Conversely, cooler temperatures boost solar panel performance. Energy production may increase up to 20% on an unseasonably mild 50°F winter day. The panel rating remains the same, but the colder climate allows it to operate closer to its full potential.
Optimizing Panel Orientation
The orientation, or compass direction panels face, greatly affects energy production. Solar panels produce the most power when pointed directly at the sun. For stationary RV systems, optimal orientation is True South in the Northern Hemisphere or True North below the equator.
Here in the north, southern exposure allows panels to capture the most sunlight over the course of a day. A roof-mounted solar array aimed precisely True South will produce the greatest overall energy.
Of course, an RV isn’t a stationary installation. You may need to park in the shade or face east/west rather than the preferred southerly orientation. Expect some decrease in solar production when not aimed southward. But even non-ideal orientations deliver useful energy generation.
To compensate for suboptimal orientations while stationary:
- Seek sites with the sunniest exposure possible
- Use moveable auxiliary panels arranged southward
- Install panel tilting mounts to better target the sun
Getting squarely aligned with the sun is especially important in winter when sunlight hits at lower angles. Adjusting panel tilt from horizontal to roughly your latitude’s degree angle can raise output by 25% or more in winter.
Comparing Panel Types
Solar cell technology affects panel efficiency and productivity. Two main options exist:
Monocrystalline silicon: Made from a single cylindrical silicon crystal. Monocrystalline panels have the highest efficiency ratings, typically from 15-22%. Their sleek dark look stands out from other panel types. But they are more expensive than comparable polycrystalline models.
Polycrystalline silicon: Manufactured from molten silicon formed into small interconnected squares. Polycrystalline panels rate slightly lower in efficiency at 13-17%. But their cost is also lower than monocrystalline.
In real-world tests, monocrystalline panels can produce up to 20% more energy on an annual basis than similarly sized polycrystalline panels. However, polycrystalline models continue improving. The efficiency gap is narrowing as technology advances.
When evaluating panel types, also consider physical resilience. Monocrystalline cells tend to be more fragile and degradation-prone than rugged polycrystalline models. Harsher environmental conditions may favor tougher poly panels for RV applications.
Either panel technology can provide reliable solar power. Choose monocrystalline for maximum output or polycrystalline for budget savings. Your RV’s electrical needs and operating climate will help determine the ideal panel type.
Additional Ways to Maximize Solar Output
Beyond temperature, orientation, and panel selection, several additional techniques can improve productivity:
- Regularly clean panels: Dust, dirt, and debris block sunlight from reaching solar cells. Aim to clean panels at least monthly for optimal illumination.
- Only run essential appliances during battery recharging: Minimize power drain to allow panels to route maximum wattage to charging batteries. Avoid using high draw appliances like air conditioning during peak charging time between 10am and 4pm.
- Use a charge controller: This regulates power flow between panels and batteries to prevent overcharging. Sophisticated versions like MPPT controllers maximize energy yield.
- Select the most efficient appliances and lighting: Upgrading to LED bulbs, propane refrigerators, and other energy-saving options reduces the system size required.
- Use a tracking system: Sophisticated mounts automatically pivot panels to precisely follow the sun all day. But simple adjustable tilt kits also help orient panels for seasonal changes.
Your solar equipment dealer can help select components to build an optimally efficient system for your RV’s needs. Careful planning and proper installation will pay off in free solar power for years of off-grid adventures to come.
Solar Performance Examples
To understand how solar panel ratings translate to actual production, let’s look at some real-world examples. We’ll use an average mid-sized RV like a 25′ travel trailer with roof space for 400W of panels.
Clear Sunny Day
On a perfect clear day reaching 80°F, the 400W solar system operates near its rated peak capacity from 10am to 4pm. The panels charge the RV’s batteries with a continuous 400 to 480 watts of solar energy during these peak daylight hours.
Over the 6 hour solar window, the 400W system delivers 2,400 to 2,880 watt-hours of energy. This easily replenishes the RV’s battery bank with ample capacity left over to run appliances.
Partly Cloudy Day
When a sunny day includes intermittent light cloud cover, the panels experience partial shading. Their wattage dips below the peak rating during cloudy periods. Expect more variability in output.
For example, the 400W system may produce:
- 200W from 10am to noon as clouds partially block the sun
- 400W from noon to 2pm as the sky clears
- 300W from 2pm to 4pm as some clouds return
The total on this changeable day is 1,800 watt-hours. While less than the perfect sunny day, it still adequately charges the RV batteries with surplus energy to spare.
Hot Sunny Day
On a sweltering 95°F summer day, the solar panel efficiency decreases due to overheating. Even with full direct sun, output is now reduced.
Rather than peak production, the 400W system may yield:
- 320W from 10am to noon as the panels heat up
- 280W from noon to 2pm at the day’s hottest point
- 260W from 2pm to 4pm remaining quite warm
The total energy generated is now 1,560 watt-hours – still usable for battery charging but significantly below the panel’s rating. This demonstrates solar production dependence on temperature.
Cloudy Overcast Day
When the sky is overcast and gloomy even at midday, solar output is at its lowest point. But with diffuse light from cloud cover, some energy generation is still possible.
For a completely overcast day, expect very minimal solar productivity:
- 60W from 10am to noon from dim diffuse light
- 90W from noon to 2pm at the brightest point
- 45W from 2pm to 4pm as light fades
The total wattage is just 495 watt-hours – not enough for full battery charging but still helpful. Even gloomy days can harness some solar energy.
Improving Performance
Compare the range of scenarios above. When possible, follow tips like cooling panels and optimizing orientation to achieve top performance closer to a panel’s rated output. Monitor your RV’s solar production under different real-world conditions to determine if system upgrades are worthwhile.
Adding supplemental panels helps compensate for reduced output on cloudy days or in suboptimal conditions. Some RVs also incorporate backup generators or shore power connections for times when solar alone can’t meet electrical loads.
With smart system planning and design, your RV solar array can deliver sufficient energy year-round even at lower productivity. Use solar power’s natural ebb and flow to your advantage.
Sizing Your Solar System
When designing your RV solar setup, start by estimating your average daily energy consumption. Common household items like lights, appliances, and electronics each consume different amounts of power. Total your expected electrical loads to determine overall energy needs.
As an example, a typical RV daily usage may include:
- LED lighting: 200 watt-hours
- Propane refrigerator: 500 watt-hours
- Cell phone charging: 50 watt-hours
- Laptop computer: 100 watt-hours
- LCD Television: 250 watt-hours
This totals to 1,100 watt-hours of average daily electrical consumption.
Next, choose solar components capable of meeting these needs. Consider your typical travel routes and weather patterns when selecting panels and batteries.
For the 1,100 watt-hour load above, options may include:
- 400 watt solar panel kit
- 200 amp-hour absorbent glass mat battery bank
- 20 amp mppt solar charge controller
- 1,000 watt pure sine wave power inverter
This would comprise a robust solar system able to accommodate the listed appliances and electronics. The 400 watt panel capacity combined with a large battery bank provides power reserves for usage spikes or inclement weather.
Proper sizing also leaves room to expand your system over time. You may wish to add a satellite antenna, air conditioning, or other equipment down the road. Allow space on your RV roof and budget for upgrading solar panels and batteries when needs increase.
Consult with solar professionals to ensure your system is tailored to your specific RV model. They can assess your electrical appliances, anticipated boondocking durations, and typical weather patterns at frequented locations.
Using energy efficiently is also key. Upgrade to ultra-efficient lighting, ventilate instead of air condition as feasible, and consolidate tasks that use heating elements or motors. The smaller your electrical appetite, the simpler it is to meet with renewable solar.
Helpful Products to Maximize Solar Output
Upgrading RV solar panels and accessories can help overcome real-world performance challenges. Here are some products to consider:
- Solar Boost 50: Adds a 50-watt panel that tilts to face the sun for seasonal adjustments and increased winter output.
- Solar Suitcase: Portable panel kits that are light and compact for supplemental charging flexibility. Arrange suitcases in optimal sun orientation.
- Renzetec Solar Tracker: An automatic single-axis tracker that pivots panels to precisely follow the sun’s movement for maximum energy collection.
- Solar Charge Controller: Use an MPPT controller like the VicTron SmartSolar to optimize charging efficiency by up to 30%. Regulates power between panels and battery.
- Yeti 1400 Lithium Battery: Upgrading to lithium iron phosphate batteries increases solar capacity and efficiency. The Goal Zero Yeti integrates with RVs and includes a built-in inverter.
- Renogy DC-DC Battery Charger: Allows you to charge your RV house batteries from your engine alternator while driving. Makes use of extra alternator capacity.
- Digital Solar Analyzer: The Eco-Worthy Solar Panel Analyzer displays live power output data, helping gauge system effectiveness for your conditions.
With some savvy solar upgrades, you can overcome suboptimal conditions and get the maximum possible performance from your RV photovoltaic system.
Creative Solutions for Shady Situations
Parking in the shade is unavoidable at times. You pull into a coveted campsite only to find trees or buildings cast shadows across your solar array. Output decreases without full sun exposure. Now what?
You have a few options to compensate when your panels end up stuck in the shade:
Try reparking your RV: Even moving a few feet one way or the other may help panels slip out of a shade’s penumbra. Just beware of blocking neighboring sites.
Use moveable auxiliary panels: Portable solar suitcases and folding panels can be arranged in sunnier spots outside the shade zone. Run extension cables to divert their extra power to your batteries.
Focus charging time: Only run essentials like the refrigerator when batteries are nearing empty. Avoid using supplementary electronics or devices during the sunny times of day to conserve reserves.
Use alternate power sources: If available, hook up shore power at the campsite or carefully ration generator use until moving on to a sunnier locale.
Planning around known shaded sites is wise. Check campground maps satellite views beforehand to pick sites with maximum solar exposure. Know your panels’ wattage decrease in shade and factor it in to length of stay choices.
When shade can’t be avoided, make the most of the sunlight you have access to. With creative charging adaptation, you can still harness solar energy even when the sun isn’t fully on your side.
Cool Solutions for Hot Climates
Heat waves and scorching temps are solar-sapping. But you needn’t abandon your off-grid adventures just because there’s a heat dome parked overhead. A few tricks will keep your solar performing despite the mercury’s rise:
Use reflective window shades: Covering windows reflects sunlight before it turns into internal heat. It also allows airflow from open vents or windows to cool without admitting more heat.
Camp in shadier locations: Seek out sites with afternoon shade that will help both your panels and interior spaces stay cooler even on blistering days. Look for shade structures or trees that block the afternoon sun exposure.
Use passive ventilation: Open windows, roof vents, and doors in the evenings to flush accumulated heat and equalize temperatures. Outdoor-rated fans can enhance ventilation. Close up in the morning before it reheats.
Cook outside: Run your stove, grill, or even microwave outdoors to keep from further overheating the RV interior at mealtimes.
Take a siesta: Close everything up midday when the sun is most direct. Nap, read, or lounge to rest through peak heat, then resume activities in the cooler evening.
Add reflective insulation: Foil-faced insulation blocks radiant heat from warming the RV roof and structure. Solar-powered roof vents actively vent hot air too.
Don’t let forecasts of triple-digit temps keep you cooped up. With a little adjusting, your RV can stay cool enough for off-grid summer camping. Fewer blistering days will make chillier fall trips all the sweeter.
Bright Ideas for Gloomy Weather
Don’t despair drab, overcast days when your panels produce minimally. A little planning and adaptation will keep you in power:
Time appliance use: Hold off on running high-draw appliances like air conditioners or convection ovens until evening or the next sunny day. Stick to minimal lighting and electronics when it’s grey.
Close up the RV: Reduce passive air exchange by closing windows on cool overcast days. This preserves interior heat accumulated on past sunny days.
Use battery power judiciously: Check battery voltage frequently. Disconnect or minimize use of devices below 50% charge to avoid over-draining.
Pull out your portable panels: Arrange one or more solar suitcases in open areas outside shade to diversify generation zones. Every extra watt of diffuse light captured helps.
Run the engine: Charge batteries through your alternator while driving to a sunnier locale. Just 30 minutes of engine time can provide hours of usable power.
Plug in: If it’s an extended stretch of storms or your batteries run dangerously low, use campground electrical hookups or a generator until conditions improve.
With smart rationing and a little luck, you can weather a string of dark overcast days. But you may long for those sunny 300+ watt days. The bright blue skies will return soon to energize your panels once again.
Solar Tracking for Optimal Orientation
Stationary roof-mounted solar panels have a significant limitation: they remain fixed in one orientation all day long. As the sun tracks across the sky, fixed panels become less than ideally aimed. The changing angles through the day can reduce energy collection significantly.
Solar trackers combat this output loss by rotating panels to follow the sun’s movement. Tracking systems orient panels directly at the sun all day to maximize illumination.
The most common tracking systems use:
Single-axis tilt: Mounts tilt panels along a horizontal axis to track the sun’s hourly angle changes. This allows pointed orientation as the sun rises and sets.
Dual-axis tracking: Uses horizontal and vertical axis motion to track daily and seasonal movement for complete 360° solar alignment at all times.
Single axis trackers typically boost output by 25-35% over fixed panels. Dual-axis
trackers can increase production by 30-40% or more. The gains are greatest in the winter when the sun is lower on the horizon.
For RVs, single-axis horizontal trackers are the most popular and practical option. They’re easier to mount and operate than complex dual-axis models. Horizontal single-axis tracking smoothly pivots panels aligned north-south to follow the sun’s east-west path.
One example is the Renzetec Solar Tracker Kit. It allows adjustable tracking for up to 160 watts of panels. The device self-calibrates position after sensing dusk and dawn lighting conditions. Then a 12-volt DC motor rotates the array incrementally throughout the day.
Other benefits of RV solar tracking systems include:
- Works with flexible panels that aren’t perfectly flush when mounted on a curved roof
- Can tilt panels daily or seasonally to match your location’s latitude angle
- Motorized tracking avoids physical panel adjustment
- Can pair with a solar charge controller to optimize battery charging
Solar trackers do add cost and complexity over fixed mounts. But the gain of 25% or more extra energy often makes the investment worthwhile. Positioning your panels for maximum productivity takes your RV’s solar capabilities to the next level.
Knowing When to Go Bigger
Is your current RV solar setup having trouble meeting your electrical needs? Do appliances strain the batteries and they need frequent shore power charging? You may benefit from going bigger.
Upsizing solar panels provides more daily charging capacity. You’ll collect more watts at peak sunlight, even with real-world derating. This helps charge batteries faster and allows more abundant energy use.
For example, doubling panels from 100W to 200W provides twice the peak charging rate. Bigger batteries store this increased capacity for overnight and bad weather usage. Upgrade from one 12V battery to an array of series-connected 6V golf cart batteries.
Higher wattage inverters better handle simultaneous appliances and devices. Consider moving to a 2,000W or 3,000W pure sine inverter to run high draw items like coffeemakers.
Before upgrading, calculate your average and maximum electrical loads. Right-size the expanded system to your needs without overdoing it. Measure your RV’s solar production for several weeks to gauge required growth.
Solar equipment is designed to make expansion easy. Add supplemental panels in parallel to existing arrays using compatible connectors. Higher capacity batteries wire together for greater storage capacity.
Upgrading solar equipment does have some downsides:
- Increased cost
- Added weight and roof space
- Complexity of large battery banks
But for avid off-grid RV-ers needing ample power reserves, bigger solar makes independence and boondocking convenience a breeze. Your travels will be unconstrained by capacity limits.
Great Solar Options for Small RVs
Owners of compact campervans, trailers, and other tiny RV homes sometimes assume limited space restricts solar capabilities. But with creative planning, even modest roof real estate can generate meaningful energy.
Mini and flexible panels: New ultra-efficient solar cells pack more wattage into smaller packages. Maneuver these flexible mini-panels around roof vents and air conditioners. Adhere low-profile laminates directly to the roof or magnetic backings for easy movability.
Auxiliary suitcase panels: Portable folding solar suits such as the Goal Zero Yeti Series offer 50-200W for flexible supplemental charging. Use the best sun exposure possible outside the RV.
Alternator charging: Upgrade your alternator and install a battery-to-battery charger to route engine power to house batteries while driving. Even modest daily drives can charge a small battery bank.
Conserve electricity: Use the most efficient LED lights, ventilate instead of air condition, and consolidate high-draw appliance use to keep requirements low. Avoiding waste is the best “upgrade.”
Secondary charging sources: Many campgrounds offer shore power hookups for a small fee as needed. Use a generator or even plug in at nearby buildings in a pinch.
Space limitations just require more innovative solar sourcing. In return for your ingenuity, you’ll enjoy solar freedom powering your adventures for decades to come. The sun provides all the capacity you need.
Solar Loans – Financing Your RV Solar System
Installing solar on your RV carries a significant upfront cost. But with solar loans, you can finance panels and equipment at affordable monthly payments. Financing makes upgrading to solar more accessible.
Secured RV Loans – Banks may approve a home equity-type loan using your RV as collateral. This ties financing to an asset. Interest rates are typically lower than credit cards.
Unsecured Personal Loans – Signature loans without collateral may cost slightly higher interest but are faster to arrange. Online lenders like Lightstream offer competitive rates.
Dealer Financing – Ask the solar installer about available financing options. Many offer low rate solar loans or payment plans directly.
Energy Efficient Mortgages (EEM) – Some home lenders approve EEMs to add solar to your primary residence. If you live in your RV, you may qualify for tax benefits and utility savings.
Crowdfunding – For RVers seeking solar as a community sustainability project, crowdfunding sites like GoFundMe pool donations to reach funding goals transparently.
Credit Cards – While not ideal for large purchases, cards allow you to earn points or cash back. Make payments promptly to avoid high interest charges.
Weigh loan terms like fees, APR, and payment timeframe. Aim for rates under 10% APR if possible. Investing in solar should pay dividends for years through energy savings and convenience.
Buying Used Solar Panels and Equipment
Used solar gear often costs 50-75% less than new equipment. Buying pre-owned can stretch your budget further. With some diligence, used solar provides affordable off-grid power.
Checkout Condition – Inspect panels closely for cell cracks, water damage, wiring faults. Test functionality. Review equipment age and performance history if available.
Verify Compatibility – Ensure connectors, capacities, and specs like voltage match your existing system. Mixing incompatible components causes problems.
Recalculate Ratings – Account for panel degradation over time. Reduce wattage ratings 0.5% annually as a rule of thumb when sizing aging arrays.
Replace Inverters – Inverters commonly fail before panels or batteries wear out. Splurge for a new UL-rated inverter for safety.
Ask About Warranty – Manufacturers’ warranties may remain intact and transferable to you. Register products in your name just in case.
Read Forums – Join the RV and vanlife communities online to search for upcoming used equipment sales. Veterans often upgrade and sell perfectly functional gear.
With some smart sleuthing, used solar panels and components help stretch your budget. Take time to verify equipment health, compatibility, and remaining life to make the most of secondhand purchases.
Common Solar Myths and Misconceptions
Despite solar energy’s surging popularity, some persistent myths confuse RV owners. Let’s demystify a few common solar misconceptions:
Myth: Solar doesn’t work in cold, cloudy places – FACT: Solar works year-round across stormy and frigid climates. Systems just need to be sized 30-40% larger to accommodate diffuse light and shorter winter days.
Myth: Solar panels don’t work at night – FACT: Solar arrays channel daytime energy into batteries that provide overnight power once the sun sets. With batteries, solar works 24/7/365.
Myth: Camping under trees blocks solar – FACT: Although shade decreases output, panels still generate diffuse light energy. Park RV in open exposure when possible or use portable auxiliary panels.
Myth: Solar only works in the boondocks – FACT: While ideal for off-grid use, grid-tied systems work equally well. Net metering sells your excess power back to the utility company.
Myth: RV roof solar limits mileage – FACT: Today’s efficient panels add minimal weight. Performance impact is negligible for most RVs. Lighter flexible panels weigh even less.
Myth: Solar isn’t worth the investment – FACT: With incentives and environmental savings, most RV solar setups pay for themselves quite quickly. The 30% federal tax credit speeds ROI.
Don’t let these tired myths deter you. Talk with fellow RVers using solar successfully, even in tough conditions. A system tailored to your needs will soon liberate you with free off-grid energy!
Ways to Get Started with Solar
Curious about solar but not sure where to begin? Dip your toes in gradually to get the hang of off-grid power:
Try a portable panel – Compact foldable solar like the Jackery SolarSaga 100W lets you experiment with free charging. Power banks, phones, and laptops from the panel through a USB port.
Install a trickle charger – Small 5 to 30-watt panels keep your RV battery topped up without needing inverters or large arrays. The ECO-WORTHY 12V trickle charger is very beginner-friendly.
Use a generator-attached “briefcase” panel – All-in-one kits like the Paxcess Portable Solar Generator combine a gas generator, outlets, and a 100W panel for hybrid charging.
Attend RV shows – Events often demo products and have experts on hand to assess your needs and recommend novice-friendly solutions. Sign up for manufacturer training too.
Consult local solar installers – Even if you DIY, pros will review your RV and usage and suggest a practical starter solar spec best matched to your needs.
Join RV solar groups – The RV Solar & Battery Facebook Group and similar online forums are helpful sounding boards with thousands of experienced members.
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