Introduction
Solar is a clean, quiet way of maintaining your deep cycle house batteries, especially if you like to dry camp. Excitingly enough, RVs are becoming standardly equipped with solar pre-wire packages. While many RV consumers want to take advantage of this contemporary feature, they often do not know where to begin. In this article, we are going to outline the limitations of solar, solar pre-wire designs, and some tips to help you determine which size solar panel will work best for your application.
Limitations of Solar
Since solar panels are subject to so much variability in terms of exposure to sunlight given the different sun angles, length of daytime hours, light density, etc., it would be difficult to use it as a direct source of energy. This is why, generally speaking, solar is not used to power appliances or household utilities directly. In off-grid applications like RVs, solar is a means of charging your house batteries and it is through your batteries that you will be supplied energy to power your unit. You must also understand that your batteries are 12V and some of your household appliances (hair dryer, microwave, coffee pot) are 110V. In order to power the 110V appliances, you will either need to be plugged into shore power, have an inverter/charger, or have a generator.
Solar Pre-Wire Designs
Now that you have a reasonable expectation of what solar can do for you, we can introduce you to some of the pre-wire designs but because “solar ready” varies across different RV manufacturers, this article is strictly touching on the solar ready units sold here at Oliver’s Campers.
Our solar ready Winnebago and Aliner units come with a Zamp 2-Pole Plug mounted on the exterior of the trailer toward the tongue on the side opposite the door. The plug has a 10ga pigtail which is usually spliced with an extension dual conductor cable that is routed to the battery bank. This design is meant to be paired with the Zamp folding portable panels that come with a solar charge controller. Note that Zamp Solar advertises a 140W “Winnebago” portable kit. This panel is designed strictly for the motorized units and the Spyder towable which are pre-wired with a solar charge controller. For both the Winnebago and Aliner units we carry, you’ll need a solar panel that includes a charge controller.
In a similar manner, our Aspen Trails, Shadow Cruisers, Cruiser Aires, Cruiser 5th Wheels, Hideouts, Tritons, Voltages, and Rubicons have a plug that is routed to the battery bank. Rather than the Zamp plug, these units come with a Furrion plug which requires a simple Furrion adapter in order to connect to a Zamp portable panel. Like the other designs, they also require a solar panel and charge controller in order to properly utilize the pre-wire feature.
Regardless of which style plug, Zamp Solar has designed portable solar kits which allow you to harvest solar energy with minimal effort. Their portable panel kits are a “suitcase” design meaning they are hinged together allowing you to fold them up or out and easily store them away in the included carrying case. The panels have legs which allow them to be propped up while they’re deployed on the ground for optimum sun exposure. The kits include the folding panel, carrying case, and charge controller that is already connected to the panel. Off the controller is a 15’ lead of 12ga cable with UV resistant jacket. The cable terminates with the 2-Pole plug that is received by the plug on the exterior of your trailer or by the Furrion adapter plug. The charge controller is programmable according to your battery profile and is compatible with all types of batteries, including lithium. If you purchased a camper outside the brands mentioned or before the implementation of this solar pre-wire, Zamp also has portable kits with alligator clips instead of the 2-pole plug which allow you to connect direct to your battery. While these portable kits are an investment, you can take pride in knowing they were designed and built here in the US.
Sizing
Determining the size of your portable kit is often dictated by energy use and/or battery capacity. In order to determine solar panel production, you can use this formula: Watts = Volts x Amps. Zamp Solar carries folding portable kits that range from 45W up-to 230W. Generally, solar panels designed for RVs operate at around 18V (this number varies but is usually between 17-22V). To be conservative, we’ll say there are 6 solar hours in a day and just remember this figure varies depending on your geographical location and the season.
For the purpose of sizing your system, let’s start with a 45W panel and apply it to the formula mentioned earlier:
45W = 18V x A
45W/18V = 2.5A
2.5A x 6 hours = 15Ah/Day
If you’re trying to match your solar panel production to the Ah capacity of your battery bank, then consider this: A 12V, 100Ah Lead Acid (this includes flooded and AGM) battery has 50% useable capacity allowing you to discharge it up-to 50Ah. If you have have a 45W solar panel that produces roughly 15Ah/day, you’re only capable of offsetting 30% of your useable battery capacity with solar alone. To fully offset your useable battery capacity, you’d need something closer to 140W of solar. If you’re an experienced dry camper who is able to stretch a 100Ah battery across a two day weekend of dry camping, then it is probably safe to assume that a 90W solar panel would match your daily energy use.
Conclusion
Whether you are trying to extend your boondocking days or possibly just trying to maintain your battery in a storage situation, the solar pre-wire might be an easy solution for keeping your batteries topped off. If you have a camper with a solar pre-wire or looking to get one, Oliver’s Campers can get you setup with what you need. Call today for pricing and availability!
