RV Solar Systems are becoming more popular with the RV community due to more people boondocking. Finding the best solar system for an RV take a little time and research. We hope to help break down the confusion to provide you with the best solar system for an RV.
What is a Solar System?
The solar system or photovoltaic system is a system used to convert the light of the sun into usable energy. The system uses wires and charge controller to transfer the energy into batteries for storage. This energy is stored within the batteries until needed. The stored energy can then be delivered in 12volt DC or 120volt AC through an inverter.
The term “photovoltaic” means the conversion of light into energy through the semiconductor. This is only one part of the system for the use within an RV. This is why will refer to the RV system as a complete Solar System. This will include a number of components which will discuss throughout this post.
How does the Solar System Work?
Without making this a huge science lesson. The Solar System works by absorbing the light from the sun through photovoltaic panels placed on top of the RV or as a portable smaller panel. Once the sunlight is absorbed it is transferred via electrical wiring to the batteries for storage through the solar charge controller.
The Solar Charge Control or Solar Battery Control works by controlling the amount of energy needed to maintain your batteries charge. It also works by maintaining the voltage within the batteries to prevent damage to your batteries. The Solar Charge Control is where you will connect any of your DC powered appliances including lights and the DC panel.
This is part of the DC system on the RV Solar System, you can attach any component needed to monitor the system. Most manufacturers will have a charge control to adapt to your system. We recommend using the charge control that matches your panels.
In simple terms, the Solar Charge Control works like the cruise control on your RV or tow vehicle. It monitors the batteries voltage levels to maintain them to a specified level. If more energy is needed, the control allows more energy to flow into the batteries. When the batteries are at a set level, the control allows less energy to flow into the batteries to prevent overcharging.
There are three different Solar Charge Controllers:
- Shunt: Rarely used, they just turn the power on and off. The problem comes when the power turns on it could produce a surge to the battery bank causing damage.
- Pulse Width Modulation (PWM): Less cost, pulsates the energy between the panels and the batteries to maintain the charge. The nominal voltage of the panels must be equal to the nominal voltage of the battery bank. For example, a 24-volt battery bank must have a 24-volt solar panel.
- Maximum Power Point Tracking (MPPT): More expensive, it will track the output of the solar panels and adjust it to maximize the output to the battery bank.
In order to power AC appliances, there will be a need for a Solar AC Inverter. Some may not consider this as part of the Solar System. However, the inverter is attached to the DC system to change the DC power into AC power for use.
Calculating you Solar System Needs
To Calculate your Solar System and Charge Controler you may need, you first figure out your usage. There are a few terms we need to cover before moving on.
- Nominal Voltage = is the way solar equipment is categorized with a margin of safety built-in and using the battery bank as a portion of the load.
- ~Voc = open circuit power or the power a panel will product under perfect conditions and without a load.
- ~Vmp = voltage at maximum power or the voltage being produced from the panel while a load is attached.
- Isc = Short Circuit Amp.
When calculating for a PWM controller, the nominal voltage for the panel and the battery banks must be equal. First, we need to check the data on the controller, find the Isc on the label. Then multiply that time the number of strings or positive leads from the panels. This number is then multiplied by a National Electrical Code (NEC) safety factor of 1.25. The result will be the minimal amp draw per that controller.
Example: Isc (8.681) x 1 lead x safety factor (1,25) = 10.85 amps minimum controler.
When calculating for an MPPT controller, you first need to know the output of your solar panel for example 420w. multiply that time the number of panels say 2. Then divide the by the voltage of your battery bank say 24 volts. This number is then multiplied by the safety factor of 1.25.
Example: 420 x 2 / 24 x 1.25 = 43.75 amp minimum controler..
You are saying well thats all great. But what size Solar System do I need for my RV?
We are getting to that. I just wanted you to understand what the controls do and how you can figure your controller needs.
First, we will need to calculate our Energy Consumptions. This is as simple as looking at all the appliances or electronics you will be using with your Solar System. Look on the labels of all those appliances and electronics for the maximum watt output. If you can not find it, don’t worry. Review the Ohm laws in the “How Does an RV Electrical Converter Work” post.
Once you know your Energy Consumption, figure the number of hours and days on the average you will be using these appliances and electronics. This is where the control calculation come handy. A PWM control is approximately 80% efficient, while the MPPT control is about 92% efficient. Finally entry the average amount of direct sunlight you will be getting each day.
Example: 200 watts x 8 hours x .92 / 10 hours = 173.9 watts.
I know that seems like a lot. But remember this is the total maximum watts of all appliances for 8 hours. Of course, we will not be using all these appliances at once. Meaning we could get a minimum Solar System of 160 watts.
Or simply go to the alte Store to hind all the calculators you will need.
Solar System Kits
In order to save a little money on your Solar System, the best option could be to first buy a Solar System Kit. You can, and just may upgrade a few components along the way. Most kits you will purchase will come with the bare minimum of components and controls.
We hind it is the Best Solar System for an RV is the one that is designed by reputable manufacturers. Most of them will have some type of package or starter kit to get you going. The important part is knowing what you need by using the formulas above. Also being informed of the different options that are available.
If you are an occasional RVer on the road less than 3 months a year total. Look into a system with the PWM controllers. They cost less and are not as big of a hit on your pocket. For the Full-timers who plan on doing a lot of boondocking, go all in with the MPPT controller.
Solar System Installation
Firstly, if you are uncomfortable with electricity, seek assistance before installing your solar system or hire a trained professional.
Now that you have purchased your new RV Solar System, its time to install it. Do a checklist of all the components you receive to make sure you do not need anything. This includes wiring, wire connections, mounting brackets, nuts, bolts, screws, and time. This will be a time-consuming project, so be ready. Here we will give you a quick overview, the manufacture recommendation may vary.
First, decide the location of the Solar Controllers and components including the AC inverter. Make sure you have enough, and the correct size wiring for all your components. This will also include the location of the battery back. When considering the battery bank location, think of ventilation. You may want to have some type of temperature control fan to keep the location at a comfortable temperature.
Batteries as susceptible to cold as much as to the heat. A way to minimize the problem is to purchase lithium batteries. These may be an added cost, almost double in some cases, in the long run, this will be a worthy investment right from the start.
When installing the solar panel on the roof. Be sure to make them adjustable in order to capture the most amount of sunlight while on location. Also remember to seal any holes drilled into the RV with Dicor, DO NOT USE SILICONE, Silicone is not designed to be in the direct sunlight on the roof of your RV.
Finally, make sure you have the wires from the solar panels secured as well. The use of EternaBond® is the best way to secure these wires. Once you have them in place with EternaBond®, they will not be coming up any time soon.
As you can see the Best Solar System for an RV needs to have the right input and output. Solar Systems have become much more popular with RVers over the past few years than those noise generator. Of course, you will need the sunlight to have the Solar Systems work to the capacity. Yet the Solar Systems can work in a low sunlight location.
We have covered a lot of information form the photovoltaic panels all the way to the batteries and how to calculate the Best Solar System for an RVs.We hope you found this information helpful and informative. Please feel free to share so others may benefit from the information you found.