Complete Guide To Installing Solar Panels
This article is the second in a series, if you have not read Calculating how big your battery needs to be. I suggest you read it first, as it explains a lot about batteries and how they should be set up. There is already a lot of information out there, but our articles are directly related to RV’s and the Australian situation. The article will expain how to get more from your batteries by either supplimenting the charging with solar or going for a complete solar system.
Not everyone who reads this needs a full system, I will cover the basics first.
Different types of Solar Panels for Caravans
Above: Glass Solar panels have been around the longest and offer the best solution in household and commercial installations.
Above: For mobile applications the semi-flexible panels offer some advantages, but generally at a more expensive price.
Above: Folding panels in both glass and flexible are very popular with Campers due mainly to the ability to move them around to catch the most sunlight.
Basic RV Solar System
A solar panel is a grouping together of individual solar cells to produce an electric current. The electric current leaves the solar panel and goes through a solar regulator then into a battery. While you can run a 12V appliance or light directly from some solar regulators, a more basic setup connects everything to the battery.
Above: A single panel generates around 17 to 19 volts. The solar regulator then reduces that voltage to a suitable charging voltage for your battery.
Multiple panels and batteries can be connected to a single regulator but that will be discussed later.
Here’s How to Avoid the Most Common RV Solar Mistakes
I get lots of questions about our RV solar and battery system. The RV solar system is large and obvious on our roof. Unless air conditioning is required where we are camping, our solar panels provide for all our energy needs.
In fielding these questions, I have determined that many solar installations do not achieve the desired outcome. Here is my list on how to avoid the most common RV solar mistakes.
Buying RV solar panels you don’t need or won’t use
Buying solar you don’t need or won’t use is the most obvious error. If all you do is travel from RV park with hookups to RV park with hookups, you don’t need solar panels to recharge your batteries. Your batteries will recharge just as well and probably faster using the power at your destination.
If you occasionally spend the night without hookups during a quick stop on a longer journey, I would argue for more or larger batteries, not for solar panels.
When you start spending more than one day in a row camping at locations without electrical hookups, this argues for recharging your batteries with solar panels. Then the question becomes, how often do you camp this way? If only once or twice a summer, then a generator might be a better, less expensive answer. If you do get a generator, get a quiet one.
If your battery discharges overnight to a point of concern, you need a larger capacity battery or a lower draw from the battery. This does not argue for a solar panel to recharge your battery in the daytime.
Instead of RV solar or a generator, you could use your truck engine and alternator as a generator. Be careful here, small engine alternators are not designed to provide long-duration high amperage battery recharging. Be especially careful with this option with lithium batteries; they don’t resist the charge and can damage an alternator quickly.
Guessing at what you need
Most people don’t have any idea about how much electricity they use. The best way to tell how much electricity you use from a battery is by measuring consumption using a shunt-based battery monitor. I did this before installing solar on my two different RVs.
My choice is a Victron 712 model that reports discharge to my cell phone. A slightly less expensive option is the Victron Smart Shunt. There are even less expensive shunt-based battery monitors, but I don’t have any experience with them. If the battery monitor does not have a shunt, then choose a different product. Once you have a shunt-based monitor, then you can measure your electricity use. If you are only using voltage to determine usage, you are simply guessing. Here is an entire article on that subject: Battery monitor — the missing critical part.
Guessing is not a good substitute for measuring.
Once you know how much electricity you use, then you can start designing your RV solar system. Start designing by figuring out your battery size. A good rule of thumb is to size your battery so that you can operate for 24 hours without recharging. Once you have enough battery to run 24 hours, you can then determine how many solar panels you need to perform the recharge.
Installing panels that are not exposed to full sun
Any little shade kills the energy production of the panel. It is better to have a poor orientation on the panels than it is to have shade on the panels. Depending on how your system is wired, shade on one panel can even kill the energy production of the adjoining panel.
Solar panels are designed to sit in the direct sun. When they are in the shade, they sometimes can produce only 10% of their potential energy.
Installing panels flat on your roof
If solar panels are installed flat to the roof, their operating temperature will increase, and as this happens the output of the panel will decrease. The effect isn’t quite the disaster that installing panels in the shade is, but they will not perform nearly as well without air circulation behind the panel.
Be sure to allow for airflow under and around your solar panel.
Failure to account for true performance and expansion
Almost always, due to less than ideal orientation, your solar panel needs to be oversized by a factor of about 30%. If the panel says 100-watt output, you can count on about 70 watts of usable power per hour during the peak exposure hours, which is about five hours per day, even in the winter. Summer will give you about two extra peak exposure hours. Don’t expect a 100-watt panel to produce 500-watt/hours of usable energy each day.
Lead-acid batteries also degrade solar panel performance because they resist being charged. My guess is that when I was charging lead-acid batteries using my first solar panel system, I cut solar performance by more than half.
Conclusion
Mistakes cost money; make a minor error and performance will suffer. Make the wrong mistake and the entire system won’t work, or won’t work for very long. I haven’t even addressed the most basic mistakes of not including fuses and switches in the right location. Avoiding mistakes in RV solar is not difficult but it requires diligence.
RVers looking for valuable how-to information have learned to go to the experts. Forums such as iRV2.com and blog sites like RV LIFE. Do It Yourself RV. and Camper Report provide all the information you need to enjoy your RV. You’ll also find brand-specific information on additional forums like Air Forums. Forest River Forums. and Jayco Owners Forum.
Related articles:
Scott Fox is a retired Navy pilot and flight instructor that has been traveling full-time in his RV for almost four years. Scott’s first experience with RVing started as a youth in a small travel trailer with his family. Overall his camping experience spans well more than fifty years. FoxRVTravel.com shares stories and explains some of the more technical aspects of RVing. Both this article and FoxRVTravel.com are freely given without financial compensation by this publisher or by anyone else in any way. He explains that he just wants to help people get the straight story with no strings attached.
Reader Interactions
Комментарии и мнения владельцев
The blog “HANDYBOBSOLAR” provides a wealth of information from a guy who has been using solar in his RV and off grid home for over TWENTY YEARS, he documents his experiences along the way. Ps he is a bit eccentric and a bit of cranky pants
I’m full time in a Roadtrek class b. I replaced the noisy gas hog Onan with a Honda 2200i. I built a custom rack on the back where the generator is inside a compartment until I need it. Then I unlock the door and slide it out. Most of the time it only has to run for several minutes as I nuke something in the microwave, so I can leave it locked on the carriage. If it needs to run a longer time I unlock it and place it on the ground where the exhaust will be blowing away from me. This has worked great for me now for three years.
It was not mentioned, if I change to lithium iron phosphate batteries, do I need to change out the converter that is keeping my batteries charged, to a lithium iron phosphate battery compatible converter
Scott, thanks for the great write up! So much applies to boating, and I was just discussing many of these items today with a fellow boater. I too am a fellow Navy pilot. wings 4/81, E-2’s west coast.
How would you suggest an RV owner charge their batteries with when the unit is parked in outside storage?
There is a small solar battery charger with controller (so it will trickle charge and/or shut down when the batteries are fully charged) for sale at Batteries Plus, most auto parts stores and on Amazon. I have also seen them at RV stores but they cost more. Make sure the charger and controller are for your specific type of battery. For example, Auto parts stores are more likely to only have a solar charger whose controller is for a gel or lead acid auto battery.
Hi Scott – I have a 1960 Vintage travel trailer this is going in for a restoration/remodel early next year and adding solar for boondocking is on the list. My ex-boyfriend had this all figured out but since we are not together anymore I’m trying to figure this out on my own. I definitely learned a few things from him and your article is a great guide and supplement for me as I navigate this on my own. Per your suggestions I will start with a battery monitor with Lithium batteries and see how much power I’m using first. I also love the idea of portable panels vs installed on the roof. Parking in the shade and putting the panels in the sun makes perfect sense. I will be following your articles and so appreciate the way your explain things. Thank you so much. You are my new solar system guru!! Tracy
Good advice on designing and using solar. First things first you need to determine the total watts and amperage you expect to be running at one time. This information can be found on the appliances. I boondock 90% of the time anywhere from the NW to SW with a few trips to the eastern states. I run everything in my travel trailer including the A/C, Frig and Microwave off my solar and battery bank. I have three 330 watt REC split cell panels. The REC panels do not degrade in shade like most panels due to their “split cell” design. For batteries I have three 100ah AGM deep cycle VRLA batteries driving a 2000 watt AIMs inverter. My solar charger is a Victron 150/70. For my A/C I installed a Smart start to reduce the initial power needs. Also, all wiring is 8 AWG except for paralleling the batteries and the run to the inverter which is 2 AWG. My advice is to learn all one can than do a lot of research of parts followed by plan, plan, plan first. Research the different types of solar panels and solar chargers. Learn about batteries so you can make the best choice. It’s best to do a little overkill that to have a system that is too small. I also like lithium batteries; however, I calculated that I can change out my AGM’s four times before equaling the up front cost of lithium.
I have a portable RV Solar Panel. It has charged up the battery but suddenly nothing in the RV was working: lights, water pump, awning. I detach the solar panel from my battery and now everything works. Any ideas why?
Given where we are with climate change and energy costs, I find it disapointing how quickly the use of inefficient and highly poluting generators are recommended. In addition, over a lifecycle, generators are not more expensive per kWh than solar. We all have to do our part, sometimes spending a little more for the greater good. An example would be if we replace Windows in our house; should we spend more for insulated or not? Last I checked the payback for insulated Windows was approx 20 years. Even so to save energy and reduce the use of fossil fuels most of us will spend more on insulated Windows.
Too many issue with solar panels to charge your deep cycle batteries. Save the headache to get yourself a 2000 watt inverter generator to charge your batteries, and power can be had even if the sun is not shinning,like when it is overcast, raining, or at night. Now, what batteries to buy. Best is never what you want or need. If you are going a few trips a year, deep cycle lead acid battery from Walmart will suffice. Yes, there are pros and cons. But, they cost a lot less than lithium ion deep cycle batteries, and without the problem of not properly charging them. Yes, they have a better power profile than lead acid batteries, but again. they are much more expensive.
The Limits Of Solar Power For An RV
When we really roll up our sleeves and take a good hard look at the size and cost of a 12,500-watt solar array, we get a true glimpse of solar power’s limitations.
There just comes a point where there simply isn’t enough feasible room to meet high wattage demands.
Yet you also have to keep in mind that photovoltaic technology is still in its relative infancy.
There is a lot more room for growth and evolution in both the materials, engineering, and manufacturing technology.
Just like a lot of innovative markets, the growing success we’re seeing in commercial solar power shows promise for what might be financially feasible at the retail level one day.
Can I Install My Own RV Solar System?
Let’s say you want to shave a little bit off the cost of a solar power system on your RV by performing the installation yourself.
For a particularly handy person, with a well-equipped toolbox, you can install your own solar power system.
Though, you will need to get your hands on more than just some solar panels, batteries, and a spool of wire.
If you really are gung ho and want to install your RV’s solar power system you will need the following things:
- A Charge Controller: It essentially acts as a regulator to help deliver power from the photovoltaic solar array to your RV solar system’s battery bank. As the RV battery bank nears maximum capacity the charge controller will gradually taper the charge going into the system to keep from accidentally overloading and damaging your batteries.
- An Inverter: Which converts the DC (Direct Current) produced by the solar panels that are stored in the battery bank into the AC (Alternating Current) used by most of your RV’s appliances.
- Mounting Gear: This usually comes with the solar panels in the initial purchase. Though with some discount models the mounting gear isn’t always “Robust.” So, you might want to give it a good hard look and upgrade any hardware components that might be suspect.
- 12 Volt Batteries: You’ll need enough 12 Volt batteries to store the proper amount of charge. While you can save a little bit of money by going with a traditional lead-acid battery, I think you’ll see a longer return on your investment and more reliable performance by spending the extra money on a deep cycle 12 Volt gel battery.
Frequently Asked Questions
Can I Drive My RV At Highway Speed With Solar Panels On?
This depends a little bit on how your solar panels are mounted. If you have them secured flush to the roof of your RV with robust fasteners and bracing hardware, there won’t be a lot of surface area for the wind to grab a hold of.
Still, driving an RV at highway speed causes a lot of vibration, which could damage a static mounted solar panel on the roof.
If your RV array is set at an angle, then the wind very likely could get enough lift to tear them loose.
Ultimately, it’s better to remove the solar panels before setting off at speeds that would exceed a leisurely drive on suburban roads.
Otherwise, you’re going to end up with lost or damaged solar panels, which will eat up your return on investment.
How Can I Maximize The Performance Of My RV’s Solar Panels?
Seeing a healthy return on your solar investment starts with making the most out of their performance.
The more electricity your solar panels produce, the more money you are saving on things like shore power access and generator fuel.
Parking in wide-open areas with maximum exposure to the sunny sky certainly helps.
Heartland Wired for Solar (locate) Panel and Controller
If your solar panels can be tilted, you might find an uptick in performance by setting them to the same angle as your degree of latitude is on the Earth. It’s a minor improvement, but every little bit helps.
Are There Other Green Alternative Energy Options To Help Augment An RV Solar Array?
Let’s say your goal is to come as close to a zero-carbon footprint as possible when RVing.
While the realistic limit of your RV solar panels might not meet all your creature comfort needs, like running the air conditioner, there are a few intriguing ways to generate power without having to tap into the grid.
Consumer-level wind generators have been seeing a robust evolution in performance recently.
With a modest breeze, you could even see an additional 500 to 600 watts by adding a wind generator that costs 400 to 500.
Of course, the problem with wind is that it’s not always blowing, and even a gentle breeze is rarely enough to generate real power.
It’s also inconsistent, so you can’t really rely on it as your primary power source. Your location also matters with a small scale wind generator.
Still, If you like to camp near the beach or in the mountains, there might be enough available breeze to give your RV’s wattage production a boost, without having to fire up the generator.
If you like to stay in the forest, where trees and brush can block the breeze, then a wind generator is going to take a while to give you a real return on your investment.
How To Know How Many Solar Panels You Need For Your RV
Knowing how much solar power you need for your camping comfort involves figuring out a couple of pieces of information. These two parts of the equation help you determine how many solar panels you’ll need for the sun’s power to deliver the electricity you want. The two parts of this equation are:
- How many watt-hours will you use each day? (energy used)
- How much energy do your solar panels provide to your battery/batteries? (energy stored)
You must balance all of this for an optimal system. Solar panels without enough batteries to store all of the power they produce will waste your money and not provide the power you need.
Conversely, one solar panel and lots of batteries will not allow enough of the sun’s energy to be harnessed to fill those batteries for your use!
Figuring out this balancing act can take some work and requires an entire article of its own to explain, but we can distill down the basics here.
Calculating How Much Energy You Use
First, you need to know how much energy you use in a day. There are a couple of ways you can do this. The first involves math. Estimate how much power you’ll consume while boondocking in your RV by learning what each device or appliance you want to use consumes and multiplying that by the number of hours you’ll use that device or appliance.
Here’s an example: You have one television that consumes 90 Watts. You estimate that you’ll watch television for approximately two hours per day. So 90W x 2h = 180 Watt/Hours per day
You can do the same for every appliance or device you may want to power as you boondock, and you would add the total of Watt-hours consumed. From there, you can estimate how many panels you need.
Calculating Energy Generation and Storage Needs
A decent assumption is that a 100-Watt solar panel will generate on average 350 Watt-hours of power per day. However, this will vary significantly by location and time of year. This article by Mortons on the Move explains a way to get a more accurate result by using PVwatts.
You’ll also need to know how many batteries you’ll need to store that amount of power! One 100 ah 12volt Battle Born battery has about 1200 Watt-hours storage capacity.
Keep in mind that your solar panels will only give you the stated number of Watts under perfect conditions. Perfect conditions = direct sun pointing directly at the panel. On a rainy day, you won’t get 100 Watts from your 100-Watt solar panel. If you’re parking in the shade, you won’t get 200 Watts from your 200-Watt solar panel.
It’s also challenging to estimate the amount of power you’ll use on a given day because days are different. You may be outside all day today enjoying nature, and fall into bed and watch 15 minutes of television tonight. Tomorrow could be a rainy day, and you’ll stay inside your RV, do a lot of work on your laptop, and watch a couple of hours of television in the evening. So estimating high is usually a good idea!
Rather than estimating your daily power consumption using math, some people prefer to simply go out camping without electrical hookups and monitor their battery usage over a typical day. Installing a battery meter like the Victron BMV712 before installing solar can give you an accurate reading of how much power your RV needs.
RV Solar System Components
Before we take a look at how you install a solar system, let’s review the RV solar system components:
Battery Bank
Your battery bank is the heart of an RV’s power system. Without a battery, an RV has no way to store power. The battery is where energy provided by the sun is stored for your use. Your solar panels will charge the battery bank.
But not all battery banks are created equal, and not all are suited to the unpredictable charge cycles of solar systems. Lithium batteries for solar applications are the superior choice over lead-acid.
RV Solar Panels
Your RV solar panels will sit on the roof of your RV collecting energy from the sun in the solar cells and transferring that energy (through a charge controller) to your battery bank. Your solar panels may lay flat, or you may choose to employ a mounting method that allows you to angle the solar panels toward the sun.
Charge Controller
The charge controller mounts inside the RV. Wires run from your solar panels to the charge controller and from the charge controller into your battery bank. The purpose of the charge controller is to control the rate at which your batteries charge. The charge controller is required to prevent overcharging and in the case of an MPPT charge controller, operate the panels as efficiently as possible.
Inverter
The electricity from your batteries is 12-Volt DC electricity. With this, you can power all 12-Volt devices and appliances as well as the 12-Volt (cigarette lighter) ports in your RV. If you want to use 120-Volt AC electricity to power a coffee maker, laptop, Instapot, or anything that requires AC, you’ll need an inverter that transforms 12V DC power to 120V AC power.
You’ll mount your inverter inside your RV as close to your battery bank as possible, and your AC appliances and devices will receive the transformed (from DC to AC) power from that inverter.
Do You Need To Use RV-specific Solar Panels?
No! Any type of solar panel can be made to work with an RV; however, there may be some challenges.
First is space available. An RV roof may have lots of stuff on it and require the use of smaller panels. If the roof is wide open, full-size residential panels like used on homes can be used for RV solar panels.
The second challenge with non-RV-specific panels is the voltage they operate at. Most RV solar panels are around 17-20 volts which will work with most PWM charge controllers to charge a 12-volt system. Home solar panels are usually 40-70 volts and cannot be used with PWM charge controllers.
You can use MPPT style controllers as long as they have a high enough voltage rating. Using an MPPT controller allows the use of most of any solar panel for an RV.
How To Hook Up Solar Panels to RV Batteries
Now that we know how many solar panels you want to add to your RV let’s figure out how to connect them to your RV batteries to produce the electricity you need!
Solar electric systems for RV’s vary enormously, especially if installing a larger system, make sure you are confident working with electrical wiring before taking this on. For systems up to a few hundred watts or kits, the voltages are not dangerous and can be installed by anyone. Regardless of the size, the following instructions are a high level of how the components should be wired.
Let’s assume that you’ve purchased a kit containing the solar panel system parts, and you have a battery or battery bank installed in your RV.
- A solar panel (or more than one, depending on what you’ve opted to buy).
- A charge controller.
- A wiring harness (and possibly connectors, adapters, and mounting brackets)
You may also want a battery monitor and an inverter (to turn that 12V DC power into 120V AC power).
Steps for Connecting RV Solar Panels to Your RV Batteries
Here are the steps to connecting your solar panels to your batteries:
- Mount your solar panels on the roof of your RV.
- Mount your charge controller inside the RV as close to your batteries as possible.
- Run your wiring from the solar panels into the RV and over to the charge controller. (You can run your wiring through a refrigerator vent or through the holes where the plumbing enters the RV if these are located near your batteries. If not, you can drill a hole through the roof of your RV to run your wires and thoroughly cover and caulk any drilled holes.) You should install a fuse or circuit breaker on the wires for this run.
- Connect the wires from your charge controller to your battery bank. A fuse slightly larger than the charge controller’s rated current should be installed on these wires.
- At this point, the system is fully installed but the RV solar panels are not connected to the charge controller. Before making the final connection it’s important to double-check all wiring to make sure polarity (positive and negative) are all correct. Once confident you can plug in the solar panels to the charge controller. We recommend doing this at night or with the solar panels covered by a blanket to prevent a spark.
- This step is optional, but if you want to use 120-Volt AC appliances, you’ll want to mount an inverter inside your RV, as close to the batteries as possible, and run appropriate wiring to that inverter.
Note: If you are wiring your solar panels/controller directly to your battery bank, there is no need to disconnect the existing converter in your RV. Both the converter and the solar panels will be able to supply charge to the battery bank.
Solar Power Systems and Installation for Recreational Vehicles
Solar Power Australia’s conversion of a Delorean DMC-12 to a performance Electric Vehicle was completed on the 27th June 2012. We are pleased to say that the conversion was a success with the electric drive providing much better performance than the V6 petrol engine.
As the vehicle is charged from outlets in solar powered buildings only….it is EMISSION FREE!
Battery BACKUP for Home. DIY Step by Step
For more information, please visit the DMC-EV page.
Motor Home Bifacial Solar Panel
We installed two 110/50W bifacial solar panels and a Plasmatronics PL40 solar regulator on this large Winnebago motor home. The solar panels are spaced above the white roof to allow light travelling around and through the solar panels to reflect onto the rear surface of the bifacial panel to produce additional power.
The space also allows air flow under the panel to reduce operating temperatures and increase power output. The 12V bifacial panels used in this installation are each rated at 110W on the front face and 50W on the rear face.
Campervan Bifacial Solar Panel Installation
We installed a single 110/50W bifacial solar panel and a Steca 12A LCD solar regulator on this Jayco pop-top campervan.
Utilising Jayco’s standard roof racks, the solar panel is spaced above the white roof to allow light travelling around and through the solar panel to reflect onto the rear surface of the bifacial panel to produce additional power. The space also allows air flow under the panel to reduce operating temperatures and increase power output.
Motor Home Uni-Solar Panel Installation
This motor home installation features Uni-Solar panels and a Steca PR2020 solar regulator.
Our method of installation ensures that there are no water leaks and no solar panels flying off on the highway. Our custom brackets follow the contour of the roof to ensure a good, reliable bond.
Uni-Solar panels are known for good performance in high temperature conditions.