Want to boondock with solar? It’s so easy. Any off-grid solar powered system just needs to do four things: 1)Transform solar energy into an electrical current (solar panels); 2) regulate the electrical current for appropriate battery charging (charge controller); 3) store the electrical energy for later use (battery); and 4) transform the stored current to power household appliances (inverter).
Easy, right?
Look: We get that solar can be a little daunting for beginners. We’ve been there. When we built our own solar-powered system in 2012, there was a barren of resources. But now, 12 years later, we have good news: There’s an all-you-can-eat buffet of information. Some of it is great, and some of it … not so much.
Taking the lessons learned from 12 years of living with solar, we created a worksheet to help RVers size, select, and price out the components needed to build a custom, off-grid, solar powered system.
AC/DC: The Two Rockstars of Electricity
Direct Current (DC) = current that flows in one direction within a circuit from source to appliance, just like water, from a place of higher pressure to lower. Solar panels create and batteries store/release DC current. Appliances including lights, fans, water pumps, smartphones and even some RV refrigerators can run directly off of DC power.
Alternating Current (AC) = current that moves back and forth from the source to the appliance all along the circuit. It is the type of current that connects to our houses, and powers a standard household outlet. Anything with the typical two or three prong plug needs AC power in order to function.
Basic Electrical Terminology
Forgive us if you’ve already read our summary of a few of these essential terms in our previous article. Understanding them is so vital, it’s always good for a little review. Let’s use the analogy of water flowing through a pipe to discuss these terms.
Voltage/Volts (V) = a unit used to measure the pressure within the electrical system. Imagine water flowing through a shower head, volts would measure the pressure of the water in the system.
Amperage/Amps (A) = a unit used to measure the flow of the electrical current in the system. Back in the shower, if volts is pressure, amps measure the flow rate of the water moving through it.
Wattage/Watts (W) = the unit used to measure the work completed by the electrical system; it is the product of volts and amps. This is an important equation to remember, W = V x A. Using our analogy, wattage measures how well (and how satisfying) the shower worked at cleaning you.
Watt Hours (Wh) = (W x time) the total hours that a system can do work at a given flow rate and pressure, or the length of time that you could take a shower at the same pressure and flow.
Amp Hours (Ah) = the number of amps that a battery can deliver in 1 hour at its nominal voltage (e.g. 12V). For example, a 100Ah deep cycle battery can provide 100A for 1 hour -OR- provide 1A for 100 hours. In shower terms, you could have a firehose for 1 hour -OR- a trickle for 5 days.
View our “Solar 101” video for more information.
Calculating YOUR Daily Watt Hours
Everyone will use their RV off-grid differently. So, it’s important to do your own energy audit rather than relying on the same system as your RVing neighbors. Relax, it’s just middle school math. And our worksheet does most of the calculations for you.
The first step is to figure out how many watts each of your appliances requires. While most AC appliances are already listed in watts, many DC appliances just list the amps because the voltage may vary. If you only know the amps, but need to determine the appliance’s watts, what would you do? Remember our friendly equation: watts = volts x amps
Examples:
- Fan Vent: 12V (DC voltage of your system) x 1.9A (amps of the appliance) = 22.8W
- LED Light Strip / Bulb: 12V x .667A = 8W
If you can’t find the wattage of your appliances, use this Wattage Chart for Typical RV Appliances. Some appliances have a wide wattage range, so it’s always best to determine the wattages of YOUR appliances.
Watts x Hours = Watt Hours (WH)
Now that you’ve determined the watts of each appliance, estimate how long you will run them. Using the watts for each appliance, multiply the watts for each appliance x the hours you typically use EACH appliance EACH day.
Examples:
- Fan: 22.8W x 4 hours = 91.2WH
- Coffee Maker: 1200W x 0.25 hours = 300Wh
- Lights: 16W x 5 hours = 90WH
- Laptop: 65W x 6 hours = 390WH
Add all of these WH together to reach YOUR TOTAL Watt Hours, or what we like to call YOUR “magic number.” This will help you choose which and how many components that you need. And here’s where our downloadable worksheet will help you keep track of everything in one place.
In our next installment, we’ll walk you through a self-assessment to determine if you have what it takes to DIY your own RV solar powered system…or hire a professional installer?
What to Look for in a Solar-Ready RV (Part 1)
5 Solar Components Every RVer Should Know (Part 2)
RV Solar Explained … with Middle School Math (Part 3)
Determining How Much Solar Power My RV Needs (Part 4, Coming Soon)
Should I Attempt a DIY Install for My RV? (Part 4, Coming Soon)
Choosing the Right Solar Powered System for My RV (Part 5, Coming Soon)
