So, you’ve gotten yourself a solar-ready RV, and now you want harness energy from the sun, huh? And store it for later use, of course. Then make it usable to run ordinary household appliances in your RV, right? Well, that requires four simple solar components: solar panels, charge controller, battery bank, and an inverter. And to really trick out your off-grid RV, let’s throw in a fifth component — the DC to DC charger!
Important Electrical Terms to Master Solar
Before diving into the solar components, let’s introduce a few electrical terms that you need to know. To simplify, I’ll use the analogy of water flowing through a garden hose to illustrate. Amperage (A) is the flow of current through the electrical system. Or, in our analogy, the flow of water through the hose. Voltage (V) is the pressure of the electrical system, which is like the force on the water moving through the hose. Wattage (W) is the electrical work being done by an appliance itself. With our analogy, that’d be the overall effectiveness of the hose.
To increase flow, you need a bigger hose, but the spray will lose pressure. To increase pressure, add a nozzle which restricts the flow but increases the spray power. While either one may still get that bird poop off your RV window, the important thing to remember is that to get power (W) you multiply the flow (A) times the pressure (V) – Amps x Volts = Watts.
One last term to understand is Watt hours (Wh). Watt hours are the amount of time you could do the electrical work with the given energy supply. Or, back to our analogy, how long you could wash the RV with the hose at the same pressure and flow. It is simply watts times hours. (We’ll cover how to determine your RV’s average daily Wh in our next blog.)
5 Essential Solar Components
Here’s a quick look at what each of the five major solar components do. I’ve also included how each is rated using the different units of electricity described above.
1. Solar Panels
Solar panels produce an electrical current when sunlight shines upon them. That current can run a DC appliance directly, but most off-grid systems use batteries to store that energy for later use. (For example, when it’s after dark, cloudy, or raining.) Solar panels are rated in watts (W). The watts of a specific solar panel (e.g., 100W, 200W, 300W) indicates the maximum power a panel can produce under optimal solar conditions. Solar panels come in either rigid, flexible, or bifacial varieties. They can also be permanently fixed to the roof or set up on the ground near the RV. (Portable solar panels are made specifically for this purpose.)
2. Charge Controllers
The charging current from the solar panels will fluctuate based upon what’s happening in the atmosphere (passing clouds, etc.). Charge controllers manage the charging current between the panels and the battery bank. They act as the “brain” of the system, and ensure that the battery bank is charged appropriately and safely. Charge controllers are rated in amps (A). The specific rating (20A, 40A, 100A) is the upper limit of current that the controller can safely handle. The two different types of charge controllers are PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking) — with MPPT being up to 30 percent more efficient!
3. Deep Cycle Batteries
Deep cycle batteries come in various voltages (12V-24V-48V), but their capacity is rated in amp hours (Ah). That way, you will know the length of time you could expect a specific flow in amps. There are four types of solar deep cycle batteries: flooded lead acid, gel, AGM, and lithium-ion phosphate. Deep cycle batteries are designed to be discharged and charged many times over their lifespan. And they can vary significantly with regards to their chemistry, price, lifespan, charging time, cycles, etc.
4. Inverters
Inverters are rated in watts (W) because they do the work of changing DC power to AC power for your appliances that have a standard household plug. Their rating (700W, 1000W, 3500W) indicates the maximum power output that an inverter can safely handle. Pure sine wave inverters most closely replicate the type of AC power that is delivered to your home and are less likely to damage sensitive electronics.
5. DC-to-DC Chargers
DC-to-DC chargers make use of excess engine power while the vehicle is running to effectively charge the RV battery bank. These chargers serve as an electrical “pump” — taking that trickle charge typically delivered through a 7-pin trailer connection and pumping it up to 30A, 40A, 50A, or 60A. These chargers are rated in amps (A), with this number referring to the possible maximum current that the charger can safely deliver to the RV batteries. Some models even combine a charge controller and DC to DC charger into one unit to save space.
So, Now You Know the Solar Components … What’s Next?
As you dive into your own RV solar project, understand that everyone has different energy needs and uses their RV differently. In our next blog, we’ll dive into how to design a solar powered system that will work for you and your energy demands!
Enjoying what you’re learning? This article is part of our RV Solar 101 series.
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)
