Free RV Solar Power Explained
July 18, 2019
There are are many components needed for an RV solar system to harvest free power. Among those components, there are countless options. We wrote about items needed to install a solar system on your RV and realized there is some back knowledge needed before making an informed decision about what will be best for you, your rig, and your budget.
Monocrystalline or Polycrystalline?
Solar panels are a major component of the RV solar system. There are two types: mono (monocrystalline) and poly (polycrystalline). Monocrystalline solar panels are higher efficiency and more streamlined. The polycrystalline panels are lower efficiency at a lower price point. The easiest way to tell the difference is that:
- The mono has a black hue while the poly has a blue hue.
- Mono solar panels are produced from a single crystal of silicon while the poly solar panels are aproduced by melting many fragments.
- The mono has unified crystals inside each cell which makes electrons move freely inside the cells while poly has many crystals inside the cells which causes less freedom of the electrons.
One of the main companies that I have worked with before is www.continuousresources.com. They have the best value for RV sized panels with competitive prices.
|Cost||more expensive||less expensive|
|Efficiency||more efficient||less efficient|
|Color||black cells||blue cells|
Charge Controllers (MPPT and PWM)
What do they do and why do you need them?
A charge controller is another major component of an RV solar system, it regulates the current coming in from your solar panels to avoid overcharging your batteries. Overcharging batteries leads to shorter battery life. Another job for the charge controller is that they prevents power from flowing backward from the batteries to the solar panels which will lead to draining the battery.
MPPT or PWM?
The Pulse Width Modulation (PWM) charge controller lowers the amount of power into the batteries as the batteries get closer to being charged. In terms, it allows the batteries to be fully charged with less stress on the batteries.
The Maximum Power Point Tracking (MPPT) charge controller is able to convert excess voltage into amperage. Thus, allowing less time for the batteries to be charged and allowing the solar system to operate optimally at all times with less power loss. An MPPT charger is used for any system over 12 volts while the PWM is used for a maximum of 12-volt system.
|Cost||less expensive||more expensive|
|Efficiency||less efficient||more efficient|
|Amps||up to 60 amps||up to 80 amps|
|System Growth Potential||limited||more flexible|
There are three types of inverters, pure sine, modified sine, and square sine (you will rarely encounter this one). The most common ones are the pure sine and the modified sine, Those are the two that I will be talking about. Many people still use modified sine inverters in their RV due to the significantly lower cost of those inverters.
The electrical wave in those inverters is a resemblance of a wave, This process is done mostly by altering the modified sine waves into a pure sine wave inside the inverter itself. The benefits of the pure sine is a more efficient wave that consumes less power, The power can be adjusted based on the preferences through multiple power outputs. Those inverter outputs are very reliable and are recommended to use for sensitive electronics in your rig.
This is the one we have and love it: AIMS Pure 3,000 Watts Sine Inverter.
This inverter wave looks a bit like the pure sine inverter’s wave but it is more choppy, the transition of the wave from the positive to the negative is done with a few brief poses, makes those inverters not recommended for sensitive electronics.
|Pure Sine||Modified Sine|
|Electrical Wave||Smooth transition between positive and negative||Brief poses <poses or pauses?> in the transition process between positive and negative|
|Efficiency||Very efficient||Less efficient|
|Recommended for||Sensitive electronics||Pretty much nothing|
Should we drill or not drill?
Drill- Fixed or Adjustable
Fixed: Many companies make these, however, the only standard between all the companies is a Z bracket style. Make sure you purchase these as aluminum corrosion-free. Many of them are only for small (RV size not residential size) solar panels and tend to be the least expensive option.
When installing these, it is recommended to use Dicor sealant to ensure that the holes are sealed on your roof and you will not suffer from roof leaks and damages later.
Adjustable: The adjustable mounting brackets allow you to tilt the solar panels to harvest the best sun at any time during the day. They come in different sizes, depending on the dimensions of your solar panel. These also require drilling into the roof so, again, make sure that you purchase Dicor sealant to ensure that the holes are sealed on your roof.
The drill-free corner brackets mounting system is an option if you do not want to drill the brackets into your roof. Those brackets are glued to the roof with industrial adhesives such as the SIKA Sikeflex 252. After securing the brackets, you will be able to drill into those brackets to secure the solar panels.
|Drilled Brackets||Drill-Free Brackets|
|Cost||Cheap and can purchase multiples in a pack||Expensive and it requires additional parts to work properly|
|Ease of Install||Fairly easy, you drill a hole and tighten the attached screw||Fairly easy to install, You measure the corners based on your solar panel and glue them to the top.|
Which battery bank should we get?
I am going to simplify this section into two types of batteries: deep cycle batteries and lithium batteries to make it easy to discuss the differences.
Deep Cycle Batteries
A deep cycle battery is designed to be regularly deeply discharged using most of its capacity. For lead-acid deep-cycle batteries, there is an inverse correlation between the depth of discharge (DOD) of the battery and the number of charges and discharge cycles it can perform, with an average “depth of discharge” of around 50%.
Renogy 6 Volt 260Ah Deep Cycle AGM Battery Mighty Max Battery 12V 100AH Battery for Solar DEEP Cycle
Lithium batteries move from the negative electrode to the positive electrode during discharge and back when charging, these batteries have a high energy density, no memory effect (other than LFP cells) and low self-discharge, meaning you can bring these batteries to close to 0% before you have to recharge them.
If you have any further questions let us know, we will be more than happy to help further when it comes to solar, you can also Check out our RV Solar Install Blog here.