Solar Power

Harnessing the Sun

Want to be independent and boondock?
Imagine no longer needing to pay for a campground site?
While there is a cost factor, the doors that are opened are well worth the initial cost.

What is Needed?

To fully take advantage of the suns ability to produce energy you have to understand how much power you need.
Creating a power budget is the first step

Budget

Do you need 120V or just 12V, or both? This is the first question to be answered.
It is possible to meet your needs with just a 12V system to provide power for lighting.
To effectively calculate the amount of Solar Panels and Batteries you will need in your RV, you need to understand your total power consumption in Watts.
Once we know this information you may then calculate how many Solar Panels and what size Battery Bank you will need to accommodate them. Typically we add 25% or 1.25 for future needs and to provide a little cushion for the system.
Most appliances list Watts, Volts & Amps on their UL Label attached to the device.

Calculate PV Panel needed for an RV?s

You will need to make a list of the devices that you will be using and how many hours they will be operating.
Solar panels are typically rated and sold in Watts. Electrical loads are also typically rated in Watts (you can usually find the wattage on the UL Label on each device).
RV batteries are typically rated in amp-hours.

• List all your expected electrical devices
• Determine Watts for each device (Amps x Volts=Watts)
• Estimate usage of devices in hours per day
• Watts x hours= Watt hours per day
• Convert Watt hours to Amps hours
• Battery Capacity=Total Watt hours / by 12 Volts-Add extra 25%
• # of Solar Panels
• Total Watt hours x 1.25=Watt hours /5 hours of Sun=Watts of Solar Energy

Battery Bank Calculator

A 12 Volt Battery that is rated at 100 Amps-hours means that the battery can produce 100 amps for 1 hour at 12 volts.
The formula looks like this: 12 Volts x 100 Amp Hours = 1200 Watts. Knowing this information will allow you to figure out exactly how long it can power your devices or appliances and how long it will take to charge from your Solar Panels or an AC charger.
A 1000 Watt-hour Battery/100 Watt Load= 10 hours- This means that if you have a 1000 Watt-hour Battery and you need to power a 100 Watt load all you need to do is divide 1000 Watts by the load which is 100 Watts and you get 10 hours.

Types of Solar Batteries

There few types of Batteries used in Solar Systems but the primary 2 are Lead-Acid and Lithium-Ion.
A typical rule of thumb that needs to be taken into consideration in Lead Acid Batteries is 50% DOD which is the Depth of Discharge and that means the manufacturer recommends that you should not drain more than 50% of the battery's capacity.
Lithium-Ion Batteries can typically be used for whatever they are rated for so a Lithium-ion 1000 wh Battery can be used up to 80-100% and a Lead Acid Battery rated 1000 watt-hours should only be used down to 50% of its charge or 500-watt hours.
Lithium Batteries are more expensive but they are lighter they have a longer charge cycle than Lead Acid Batteries and as your need for Solar Panels and more power will be created, you'll be able to complement them using these smaller more powerful types the Lithium-Ion in your Battery Bank.
A Lithium Battery is more susceptible to cold than an AGM battery, this means they either have to be kept in a warm area, purchased with internal heaters, (above 40 degrees) or if that does not work for you, AGM may be the best choice.

How Does an Inverter Work

An inverter's basic function is to "invert" the direct current (DC) output from Batteries into alternating current (AC).
Using your highest demand for Watts whether it's a fridge at 1500 Watts or a Hair Dryer at 1100. The Inverter would have to be at least 1500 watts to match the watts of the fridge.
By adding a buffer of another 500 watts the right size would be around 2000 Watts. You do not want to run your inverter at maximum capacity as a rule.

Solar Charge Controller

Typical solar panels put out between 16 and 22 volts. RV batteries are normally 12 volts. A solar charge controller is a voltage that keeps your batteries from overcharging. There are a couple ways to accomplish this regulation, so there 2 main types of solar charge controllers:

Pulse Width Modulation (PWM) Controller-This type of device is basically a switch that connects a solar array to a battery. While functional, these devices aren't very complex; they don't adjust for greater efficiency during more or less sunny times of the day.

Maximum Power Point Tracking (MPPT) Controller: these controllers are more sophisticated in function. They can adjust their energy intake, helping to increase overall output efficiency for your solar array. When deciding on a Solar Charge Controller always buy one with a higher Amperage Rating than you actually need. This way you can add an additional Solar Panel to your system in the future without the need to swap out the controller later on.

Types of Solar Panels

Solar panels are sold different ratings and physical sizes, but a 100-watt panel is a commonly found rating, particularly for RVs.
Rigid Solar Panels-are the most common panel on the market and are composed of two standard types of cells called monocrystalline or polycrystalline cells with a layer of protective tempered glass and an aluminum frame.
The main difference between the monocrystalline or polycrystalline Solar Panels is the type of silicon solar cell they use: Monocrystalline solar panels have solar cells made from a single crystal of higher grade silicon used in the production of the panel while Polycrystalline solar panels have solar cells made from many silicon fragments melted together and laid out on the panel.
This quality makes a difference in the efficiency between the two.