Motorhomes come with built-in electrical systems in most cases. Campers, trailers, and another RV towable can either be charged while being towed by a truck or be plugged into campground hookups or shore power.
Some RVers like to have solar power using solar panels to produce an additional source of electricity. Installation of a solar power system, even a basic one, is best done by a qualified, experienced installer. All battery, solar, and electrical work is potentially dangerous! Therefore, it’s always recommended that a skilled person does the work. It’s not something for an amateur to dabble in.
As our disclaimer, you are solely responsible for any electrical work on your RV, towable, van, or another vehicle type. We highly recommend hiring a qualified electrician or solar specialist to do the work for you. It’s immeasurably safer that way. Don’t try to install solar yourself! We disclaim all liability.
RV Solar Basics
First, we’re going to list out the main parts of an RV solar system. We’re not going to drill down to every fuse, wire, and so forth. We’re aiming kind of at RV Solar for Dummies with our language and approach. Hopefully, this will be best for most people because solar power is filled with confusion! So, intermediate solar people, please don’t be offended that we’ve kept it simpler!
Second, this article is to give you a solid idea about solar power and RVing. After that, we’ve added other useful information to know before you arrange to have a solar power system installed for you.
Here are the main parts of an RV solar installation:
- Solar panels
- Charge controller system
- Battery monitor unit
- House/Coach 12-volt AC battery pack
- RV inverter (optional, if requiring AC power for household appliances)
In the next few sections, we explain these in more detail:
Harness Irradiance from the Sun
Without getting all fancy, the power of the sun is sufficient to provide more than brightness alone. It has power that can be harnessed and turned into forms of electricity. It’s unnecessary to understand the science behind that; just know that it can do it.
If it’s any easier, visualize how a wind turbine turns when there are high winds and this turning motion generates power. Solar cannot be visualized physically in the same cause and effect manner, but it still can provide additional power when the sun is shining. This provides greater independence for an RVer.
Read Also: How to Tell If a Deep Cycle Battery is Bad
Solar Panels Do the Work
Solar panels can receive the sun rays and each cell of the panel produces an electrical current. There are different types of solar panels with various pros and cons.
Silicon crystal is the primary material for solar panels. Panels come in various levels of durability depending on the quality of the product and how the individual cells on the panel are created.
Polycrystalline vs Monocrystalline for RVs? Well… actually… there are three types of solar panels, not two:
Poly-crystalline – Multiple small silicon crystals are used in its creation. Almost as power-efficient as mono-crystalline solar panels. Affordable too. Currently, the most popular type. Requires a rack system for roof installation.
Mono-crystalline – Each panel uses one crystal, not several. The solar cells comprise a thin layer of silicon. Space-efficient. Best performer in low-light conditions. Requires a rack to install it on the roof.
Amorphous – Far more sizable in panel dimensions vs. power output. Thin flexible solar panels with backing to stick the panel to the roof of an RV or camper for improved stealth. Doesn’t always need a rack system to install it. Lowest cost.
Is Solar Power Like Photosynthesis?
Plants are capable of using photosynthesis to receive the sun’s energy and convert it into the chemical energy that they require. They can also store the energy created too.
Solar panels receive the sun’s power and create an electrical current. So, it’s similar but again, different at the same time. Also, solar panels are unable to store the electricity created by solar cells. So, there’s another difference from plants.
Solar Panels are Far More Effective than Photosynthesis
Solar panels work more effectively when they are directly facing the sun at the right time of day. They can be fitted to the roof of an RV or camper. Solar is many times more efficient in harnessing solar energy than plant life.
There are fixed, inflexible solar panels and flexible ones that fit on some curved roofs that won’t accept a fixed solar panel style. When on the roof, they’re usually fitted to a rack system to ensure they stay in place when driving and don’t suddenly become flying objects!
Also, there are portable ones that can be folded out and propped up on the ground or grass and be plugged into a charge controller and onto an RV’s battery pack or a portable battery pack to store the energy created.
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The charge controller sits between the solar panel and the battery system.
Its role is to regulate the power that’s been created through solar panels. It also helps to avoid any of the batteries being over-charged (when they’re already fully charged, and the solar panels are still receiving energy from the sun).
Charge controllers come in 4 main types. These are:
- Series Regulator
- Shunt Regulator
- MPPT Charge controller
- PWM Regulator
Most RVers only need to know about the MPPT and PWM types because these are both the most common and easily available.
The PWM regulator is seen as the less expensive, more economical but less efficient of charge controllers compared to MPPT. For lower-powered systems requiring a cheaper setup, PWM can get it done.
Smaller systems often don’t see much upside when opting for more expensive MPPT charge controllers. However, if you’ll be eventually adding hundreds of watts of solar on the roof and a hefty battery bank, then MPPT is likely to be a better choice.
PWM is at least 20% less efficient in low light conditions. So, overclouded days or parking up regularly in the forest public land will make it harder to keep your batteries topped up.
MPPT Charge controller
The MPPT charge controller is the premium option. Over 150-watts of solar on the roof or folded out solar packs beside the RV or camper is necessary to see a benefit.
Also, when staying in climates where the temperature drops precipitously but the sun is still out, then the MPPT unit will perform better than PWM too. System systems use MPPT every time.
Battery Monitor Unit
A battery monitor unit is a useful addition to a solar panel system in a motorhome or towable RV.
It can provide detailed information about the current charge level in the batteries, confirm battery health, and offer other benefits too.
In modern systems, apps are available to monitor your battery charge level from a smartphone. This saves having to regularly check the readings manually on the battery monitor or charge controller.
House or Coach Battery Pack
Most RVs and campers will have one or more 12-volt deep cycle DC batteries installed in the coach’s living area. They are often installed beneath the seating in the dinette. However, their exact location depends on the make and model of the RV and whether a previous owner chose to re-install them in a different location post-purchase.
These are often connected to the starter motor in a motorhome where an alternator or other system is incorporated to trickle charge the batteries when the engine is running. Whilst this might be fine when traveling regularly, if stationary for any period, the batteries will run down unless they’re recharged.
The 12-volt DC power can run 12-volt TVs and other equipment that uses this amount of volts to operate. However, it won’t run 110-volt appliances or devices like ones used in a residential home.
There are different types of batteries including flooded, sealed, gel, VRLA acid, and lithium. Each requires varying amounts of maintenance. Lithium is usually the most expensive but the best performer. It’s necessary for the batteries to all match both type and capacity in a battery pack for best performance.
With a solar power installation by a professional, it provides a second way to charge up the house batteries to ensure you never lose power in the living space.
An RV inverter is an additional piece of equipment. Some RVs have them pre-installed whereas others do not. To run 110-volt AC systems that household appliances require, an RV inverter is used to do that. Without one, none of any of the 110-volt outlets will receive power.
There is some power loss during power conversion through an inverter. A generator can be used to provide temporary power to the RV, but it supplies dirty power that can hard electronic devices. Therefore, an RV inverter is still useful to own too.
With a solar power system, it’s an option to connect the 12-volt battery system to the RV inverter too. This will allow you to plug household appliances into the RV inverter directly but use the power stored in the 12-volt batteries (the inverter converts the power from DC to AC for you).
RV inverters also act as power regulators to smooth out any spikes or irregularities in the power created. This can save your electronics from getting messed up!
Here is a video about how one couple set up their RV solar basics system:
Any Quirks with Batteries to Be Aware of?
Batteries are a broad topic, so we’re only covering minimal information in this ‘Basics’ article.
Be aware of any maintenance requirements with the different battery types. Also, ask about the durability of the batteries to get a sense of their annual running cost.
Power Depletion is the Risk Factor
The main issue with 12-volt batteries is how much the battery can be drained before running into trouble. With most battery types excluding lithium, it’s advisable to keep them topped up between 40-60% at all times. Otherwise, it can damage the battery cells and they will not hold a full charge thereafter.
Batteries in this situation are prone to instant failure once this has occurred once. Because of this, RVers must carefully monitor their battery system to ensure it isn’t allowed to decline below the recommended safe level. Otherwise, you’ll find yourself need to replace all the batteries together. And that will get expensive fast.
Lithium Batteries Are Best
The more expensive but better option is to buy lithium batteries.
The advantage with these is that they can hold a charge reliably down to 20% or less without becoming damaged. Therefore, whilst an RVer might get 50% (55 AH) of the use out of a 110 AH battery capacity, they’ll likely get up to 90 AH from a 110 Ah lithium battery. So, there’s less chance of ruining them or running low on power too.
The downside is that lithium is considerably more expensive than any other type of deep cycle battery for an RV.
How Many Solar Panels Do I Need to Run an RV?
To get a general idea, look to have installed at least 250 watts of solar panels per 110 amp-hour of batteries (12-volts). These will either be on the roof or as a solar panel that can be unfolded and carefully positioned to capture the sun while stationary.
The rough formula can be adjusted depending on the solar panel and the charge controller’s expected efficiency. The likelihood of good sunny conditions in travel locations providing ample opportunities to fully charge the batteries is also a determining factor in how many panels and the wattage to get for them.
RVing in the winter or mostly on overcast days, it proves difficult to capture enough solar to fully charge the batteries. Therefore, at these times, more solar on the roof can be beneficial to avoid the 12-volt batteries ever being drained too much.
What Will a 100 Watt Solar Panel Run?
With a 100-watt solar panel, it can be used to power a few electronic devices.
Certainly, smartphones, tablets, a ceiling fan, a desk lamp, the router for the Wi-Fi, and a laptop will be possible for a certain number of hours. However, likely not all at once.
More energy-hungry appliances like TVs, AC units, heaters, and refrigerators will typically require more solar power to keep running. They will need so much juice that the battery will drain faster than the solar can top it back up again with only 100-watts to play with.
Benefits of a Solar Power System in an RV or Towable
Here are some of the benefits of having a solar power system installed:
- Free power from the sun.
- Greater independence from campground hook-ups, running the engine to charge the batteries or turning on the noisy generator.
- Less noise to annoy the neighbors when running the engine or the generator.
- Ability to run more appliances at the same time.
- Use the laptop, TV, or gaming system for more hours each day (good for digital nomads and remote workers in RVs).
- Can be less expensive than campground hook-ups, using a generator, or recharging through the engine.
- Maintains the 12-volt batteries better through a steady stream of electricity from solar.
- Boondock off-grid for longer before needing to head to a campground or into town to recharge and get supplies.
Many RVers choose to have RV solar installed or to purchase portable solar that folds out.
Power issues are a constant concern for people on the road. The last thing anyone wants is for the power to suddenly go out. Therefore, having an additional, cheap power generation option is a no-brainer for most campers. It is an upfront cost to bear, but it repays itself over several years and solar panels can last for a decade or longer.
Also, it’s more eco-friendly than the electricity generated by power plants, even when accounting for the materials used to produce the solar installation equipment. Therefore, solar energy has a green, feel-good factor to it too.