What To Know Before Adding A Solar Power System To Your RV
Adding solar power to your RV isn’t as simple as just installing a panel or two to the roof. Here’s a brief look at the components that go into harnessing the power of the sun as you enjoy the great outdoors.
Why solar?
If you only ever stop at campgrounds with power hookups, you could probably get by without solar power, but if your travels take you to places where hookups are unavailable, or if you prefer to camp surrounded by nature instead of rows and rows of other RVs, you’ll need a power source to use your camper’s amenities.
Know Your Power Needs
In general, you should aim to be able to go at least 24 hours before needing to recharge, so it’s important to have a firm grasp on how much power that will require before you buy a solar power system. That means accounting for the wattage of not only lighting and air conditioning and/or heating systems, but also kitchen appliances, electronic entertainment, and any other items such as hair dryers or medical devices that require electricity.
There are two main ways to accomplish this: You can calculate your watt usage by multiplying the voltage of the device by the number of amps used, or you can use a battery monitor with a shunt to get an accurate reading. Once you have established your power usage, you can decide the size and number of panels you need as well as how much battery capacity your system should have.
Proper Panel Installation
As in the world of real estate, the most crucial factor in solar panel installation is location, location, location. If the panels aren’t receiving full sun, they won’t produce the energy they should. That means they must be installed in the right spot on the RV, usually a wide-open space on the roof, and they cannot overlap. It also means the RV needs to be parked so that the panels are in the sun. There also needs to be airflow around and beneath the panels to prevent overheating.
Permanent Or Portable?
In addition to variations in size and output, solar panels come in two main options, permanent or portable. Permanent panels are installed on the top of the RV and stay there for the duration of their life. Portable panels are stored when not in use and can be set up anywhere and moved throughout the day to maximize their sunlight capture.
The biggest benefit of portable panels is the ability to park in the shade and put the panels in the sun, whereas permanent panels require the RV to be parked in full sun as any amount of shade will reduce the amount of power produced. Permanent panels, however, offer higher output and are continuously drawing in energy, even as you drive.
Beyond The Panel
Using solar power isn’t as simple as attaching solar panels to your RV and connecting a few wires. Once you have determined your power needs and installed the right number of panels in the right spots, you’ll need some other important components.
Battery
The sun doesn’t always shine, so for starters you’ll need a battery pack to ensure you still have power at night and on cloudy days. You’ll want to obtain a deep-discharge battery that provides smaller amounts of energy over a prolonged period of time, which leaves you with two main options: lead-acid and lithium batteries.
With lead-acid batteries, it is vital that you get a deep-cycle battery and not a starting battery, which provides a lot of power quickly to start an engine, but cannot supply the lower, steady levels of power required by the various appliances in your RV.
Lead-acid deep-cycle batteries come in flooded lead acid (FLA) and absorbent glass mat (AGM) versions. FLA batteries require you to add distilled water to replace water that evaporates over time, whereas AGM batteries are sealed and have a longer service life.
Lithium iron phosphate batteries, on the other hand, weigh less than their lead-acid counterparts and have a higher capacity. They recharge more quickly, have a longer service life, and are likely the better option overall, but have a higher upfront cost, which may price them out of some budgets.
Charge controller
A charge controller creates a single direction of movement for the energy, moving from the solar panels to the batteries and not away from them, which extends the useful life of the battery.
The charge controller also prevents overcharging your batteries by limiting the amount and rate of charge and prevents undervoltage by shutting the system down if the stored power falls below 50% of total capacity. The controller then reconnects the system during charging. Charge controllers also provide overload protection, as current flowing to the batteries in excess of what the circuit can handle can overheat the battery and even start a fire.
Charge controller options include pulse-width modulation (PWM) models and maximum power point tracking (MPPT) controllers. PWM controllers are designed for smaller systems and regulate the energy flow by using a series of short charging pulses. They do result in some power loss between the solar panels and the batteries because they can’t adjust voltages, they can only switch off intermittently to avoid excessive voltage.
When batteries are full, PWM controllers continue to supply small amounts of power to keep the batteries full. MPPT controllers are designed for larger power systems and draw the current at the maximum power voltage, but in limited output to prevent overcharging. These controllers monitor and adjust input as needed to regulate the current from the solar panels.
Inverter
An inverter converts DC power from the solar panels into AC power that can be used by the RV’s electrical system or vice versa to create DC power to charge batteries. This is necessary because, while some appliances in the RV can operate on direct current power, such as a 12-volt refrigerator, other devices operate at 120 volts of alternating current power and require conversion to function properly. The inverter should have a capacity of 1.25 times the total watts used at a time.
As with the other components in your RV’s solar system, inverters come in more than one variety. Voltage rises and falls with a changing frequency in a sine wave. In a pure sine wave inverter, the rise and fall are smooth, closely matching the actual sine wave and changes polarity when it moves past zero volts.
In a modified sine wave inverter, the wave changes polarity back and forth, resulting in a choppier wave. This works for some/most devices, but more sensitive electronics, such as medical equipment, require a pure sine wave inverter. Electronic devices that use AC motors, like refrigerators and microwaves, can certainly function with a modified sine wave inverter, but will run more smoothly and with less chance of possible damage on a pure sine wave model.
One-Stop Shopping
In just a few years, solar power systems for RVs have gone from custom parts collections cobbled together from a variety of sources to a growth industry powered by companies that simplify your quest for solar power by supplying everything you need as part of a single package.
Zamp Solar of Bend, Oregon, for example, specializes in solar systems for RVs from Airstream, Winnebago, Keystone RV Company, and Forest River. The company offers both portable and permanent setups that are built in the USA and come with everything you need for extended boondocking adventures.
Another solar provider, Renogy of Ontario, California, began as a student project at Louisiana State University and today offers components, parts, and complete solar power systems for a variety of use cases, including off-the-grid RVing.
Have A Backup Plan
Depending on the length of your trip and how far off the grid you’re going, it is wise to have a backup power source available, such as a generator, or other contingency plans, just in case.