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5 Signs Your RV Solar System Is Too Weak

If you have an RV solar system and feel like it’s not performing as well as you expect, there are a lot of places problems can crop up. As an electrical engineer and solar installer, I have seen many areas where solar systems have begun to fail for many different reasons. Failing solar systems can cause many issues, from a lack of performance to fires.

Even If you have a properly functioning RV solar system, it’s important to know these concepts and failure points in case you begin to experience them. It’s important to quickly address an issue before it becomes dangerous. We’ll help you work through some common signs that your RV solar system may be weakened or malfunctioning so you can head back out on the open road worry-free. 

Read on for our top five signs that your RV solar system isn’t functioning properly.

Do Solar Panels Degrade Over Time

Installing RV solar systems has increased in popularity. But do solar panels degrade over time? The answer is yes, they can.

Solar panel degradation occurs due to various factors, including long-term exposure to the sun’s UV rays and dust or dirt accumulation over time. Being subjected to adverse weather conditions also accelerates the wear and tear on solar panels. Typically, solar panels are expected to last for 20-25 years and retain at least 80% of their original power output at the end of that time.

Different solar panel types have different life expectancies as well. Most glass panels will easily make the 25 to 30-year life expectancy, but plastic encapsulated panels last far less time. These panels tend to be semi-flexible and far lighter in design. The drawback is that the encapsulated materials that hold the panels together do not last as long and are likely to begin failing between 10 and 15 years. Many less expensive semi-flexible panels last even less time. This is mainly due to degradation from UV damage of the surface or heat stresses moving components within the panel.

Cait from Mortons on the Move repairing RV solar
This is a semi-flexible panel that has a much shorter lifespan than glass panels

Most of the time, RV solar panels can easily last for the life of the RV, but regular maintenance and inspection is required to get the most out of them.

Do Batteries Degrade Over Time

Oh yes, RV batteries do degrade over time. The rate at which they decline depends on several factors. How quickly batteries degrade depends largely on what type of battery you choose. Traditional lead-acid batteries, which come with a less expensive up-front price tag, degrade much more quickly than their lithium-ion counterparts. 

A lithium-ion battery can last 10 times longer than lead acid, particularly when drained deeply and recharged partially. Because this is the primary use type for RV solar systems, we always recommend using lithium-ion batteries with these systems. Lead acid batteries are just not suited to the type of charge-discharge cycles solar provides them for longevity.

Similar to solar panels, all batteries can also degrade more quickly depending on how well you maintain them, the various elements they are exposed to, and your charging routine. If you are using lead acid batteries, it’s important to stop discharging sooner and make sure they get fully charged each charge cycle.

Pro Tip: Learn why we have continued to use Battle Born lithium batteries even on our third RV.

5 Signs Your RV Solar System Is Too Weak

Watch out for these telltale signs if your RV solar system isn’t working properly or may give out. These five key factors indicate whether or not your RV solar system could be on its way toward becoming too weak.

1. Your Batteries Aren’t Keeping a Charge Overnight

Your batteries should hold a charge overnight if you don’t run too many energy-demanding appliances. If your batteries are dying on you in the middle of the night, there are many reasons it could be happening.

Degraded Batteries

First of all, your batteries could just be old and degrading. Are they lead acid batteries that worked at one point? If so, then the deep discharges and partial solar charging could have degraded them. I have seen lead-acid batteries fail in less than a year when used in RV solar systems. Even killing a lead acid battery once will cause significant damage. The only way to test them is to make sure they are fully charged (usually with a shore or generator), then run them down with a battery meter to determine their output.

The batteries could also have internal failures, other damages, or simply age out. If the batteries are not performing, then there is a good chance they need to be replaced.

Batteries Not Getting Fully Charged

If your batteries are not getting fully charged, then you will drain them much quicker during the night. The batteries might not be getting charged because your solar system simply is not large enough to maintain your daytime use and charge the batteries. Its also possible that your charge controller settings may be preventing full charges. This can happen both with solar charge controllers and shore power charge controllers. Using a battery monitor that has a shunt is the only way to get an accurate reading of your state of charge.

Energy Usage Too High

If you are using too much energy, you will drain your batteries too quickly. If you have an inverter that is running a heater or other high-load appliance, it will run your batteries down quickly. Another big energy usage can be a furnace running its fan all night. As mentioned before, an accurate battery monitor is the only way to truly know how much power you are using. If your energy use is too high, you need to reduce it or add more batteries.

Other factors, such as extreme heat or cold, parasitic draw from appliances in standby mode, or damaged parts in the solar set-up, can also cause batteries to drain prematurely. The best tool to help you understand battery issues is an accurate battery monitor that we always recommend be installed in every solar system.

2. Your Batteries Drain Even on Sunny Days

If the sun is shining on your solar system it should ideally be producing enough power to maintain your energy needs. If the system is not producing enough power your batteries will continue to drain. Lets take a look at the main reasons this is happening.

Solar System Is Not Large Enough

The simplest cause of this is that your solar system is just not large enough to keep up with your energy needs. It’s ok if your system is undersized as it will still offset your energy needs, but you will need to keep an eye on your batteries, especially in the evening. If your batteries are getting low you will need to run a generator to make sure they will make it through the night. Alternatively you could install more panels and charge controllers to meet your energy needs.

Solar Panel or Charge Controller Problems

You also have the possibility of incorrect wiring, improper settings, or other less likely elements of a system failure. We will be taking a look at what system failures look like below, but if your system is plenty large and not putting out enough power then something could be wrong. The settings of your charge controllers could also have gotten messed up causing your batteries not to charge properly. You should be able to see the output of your solar system with your charge controllers or a multimeter with an amp clamp to determine if it’s performing properly.

Overall your battery size and performance will not affect a sunny day drain, the problem will be upstream with your solar panels and chargers, or you simply are using more power than you are producing.

Close up of solar panel on RV
If your solar panel system isn’t working as well as it has in the past, there are a few key elements you can check in on to improve the overall function.

3. Panel Output Does Not Match Ratings in Full Sun

Solar panels have a rating to produce a certain amount of power when placed in full sun. If the output amount doesn’t match this rating then it might indicate a problem. Keep in mind panel ratings are in perfect condition when facing the sun. If your panels are flat or not pointed directly at the sun they might produce 20 – 30 percent less power.

The most common issues when the output doesn’t match panel ratings are installation issues or failing components. Common installation problems are the gauge of the wire used in the system is too small, the solar charger is too weak for the system’s capacity, or the panel voltage is incorrect for the batteries.

The various elements of any electrical system must all coordinate with one another to work at maximum efficiency. If any of these elements don’t align with the rest, the system can’t properly manage the amount of energy produced by the solar panels properly.

If the system was working at one point but the system capacity has degraded significantly check wires, connections and fuses for problems. We have seen many systems with poor connections melt wires and fittings. Its even possible that these issues can short out your system.

Another big problem with solar systems is using panels that are too low a voltage. It’s generally best to have a voltage output at least twice that of the battery voltage, preferably higher, and use an MPPT controller to modulate the power. Higher voltages allow maximum output performance by enabling MPPT chargers to detect and utilize their full potential.

Pro Tip: We crunched the numbers to help you decide How Much Solar Power You Need for Your RV.

4. Your Inverter Is Not Able to Run Outlets and Appliances

An inverter is a main component used in many solar systems to provide 120 or 240V power to outlets for AC appliances. If your inverter is working but shuts down when running certain higher-load appliances you likely have a weak link in your system.

First, if only your outlets don’t work, check that you don’t have a tripped GCFI outlet. This will stop other outlets on the same circuit from working as well. You may simply need to reset it.

Bigger issues come from the inverter and battery bank. If you have weak batteries, they may not provide enough voltage for the inverter to power the outlets or appliances under heavy loads. When you put a load like a toaster on an inverter it draws an enormous amperage from the batteries and causes the voltage to sag significantly. This voltage sag increases the amperage even more and could cause the inverter to shut down. Usually, the inverter will signal Undervoltage if this is the case.

Undervoltage issues to inverters can arise from poor connections, undersized wires or failing batteries. Usually, inverters require very large wires of 4/0 or larger to handle the amperage properly. This is another place where lithium batteries shine. Lithium batteries do not have as much voltage sag and handle higher power loads much better.

Or, if your batteries have a healthy voltage (greater than 12.5 Volts) and seem to operate appropriately, your wiring is appropriately sized and all your connections are tight, you may have a problem with the inverter itself. Inverters do occasionally fail or overheat. Make sure the inverter is getting enough airflow and check if it is reading any faults.

5. Your Running A Generator Every Day

This is a more general concept about solar systems, but if you are running a generator every day even if you have a solar system its probably too weak. Many times we design solar systems to produce about 90 percent of our power needs, which means if you have sunny days in a row you should only need to run the generator every few days.

This of course is subjective to your wants and needs but in general your system should be able to provide all your power needs in a 24-hour period with full sun. If you are unsure of how much solar you need to add or what components you need be sure to read our article all about sizing an RV solar system. I have had great success with the method described in that article.

Pro Tip: Building your dream camper van? Find out How Much Solar Power Can You Put on a Van?

How Much Solar Do I Need For An RV or Off Grid Project: How To Get Accurate Calculations

What Does It Look Like When Components Fail

When components of an RV solar system fail, you usually have indicators that point toward the issue. Unfortunately, because the parts work together to provide power to electrical appliances and outlets, it can be tricky to narrow down the source of the problem. 

Here are some symptoms you can use to help narrow your search for any RV solar system component failures.

Solar Panels

The most common indication of a problem is a visible decrease in the amperage output of your system. This can happen when the modules, wires, or other components become loose and decrease their performance, thus resulting in reduced power output.

Reduced voltages or changes in voltage could also signify a failure, generally due to additional resistance in your wiring or some other component. 

You should also monitor for intermittent power surges or voltage your solar panel produces. These could mean loose connections and inconsistent power production.

Pro Tip: These 5 Best RV Solar Panel Kits for Your Camper make the switch to solar easy.

Batteries

The symptoms of failing RV batteries can be subtle but can indicate an issue with this crucial power source.

One of the most common signs is dimming overhead lights, which can cause frustration when trying to read or cook. If you find the lights repeatedly reacting slowly to controls, it can indicate diminished battery performance.

Another telltale sign of trouble is a shorter period between charges. This means that if your RV batteries were previously capable of holding a charge for four nights, you might discover they can only last two nights without needing a recharge.

Other signs might include corrosion on the battery terminals, failure of the batteries to reach a full charge, or longer charge times.

Tom for Mortons on the Move installing new RV batteries
Check the status of your batteries to see if they may be causing your solar system to fail.

Inverter

Your inverter could start to fail when your outlets and 120-Volt appliances stop working. 

But first, ensure the problem isn’t a lack of power from the batteries. The inverter takes 12-Volt direct current from the batteries and converts it to 120-Volt alternating current for outlets and appliances.

If your batteries aren’t the problem, you may have an issue with the inverter, whether from the hardware, faulty wiring, or a blown fuse.

When your inverter isn’t working, 120-Volt appliances such as your air conditioning unit, residential refrigerator, coffee maker, or any device plugged into an outlet will cease to work.

Charge Controller

Solar charge controllers have a display panel or LED indicator. If you have any notifications on the display or LED indicators, they may point to a problem with the charge controller.

You’ll likely notice that the RV batteries don’t charge or that the charge controller indicates a full charge when they aren’t. 

In this case, you may have to track down the problem by first testing the batteries and the connections between the batteries and the controller. Also, test the connections between the solar panel array and the controller.

Pro Tip: Learn from our mistakes from when We Bought An RV With Solar Installed, But It Was All Done Wrong.

Ultimate RV Off-Grid Solar System Build - 2760 Watts of Solar ☀️ 11Kwh Battery, on a 32' Fifth wheel

Can RV Solar Systems Be Upgraded or Fixed?

You must take care of the individual components to keep your RV solar system going. Like anything else in your RV, the solar panels and batteries will degrade over time.

If you notice any of these five signs, it’s a good indication that your RV solar system is weak or failing. Don’t worry, though; with a little work (and maybe some money), you can upgrade or fix whatever needs fixing and have your RV running on solar power again.

Do you have an RV solar system? Have you ever noticed any of these signs? Tell us in the comments!


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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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