The Best Solar Charge Controllers for RV in 2020
Comparison, Buying Guide, and Reviews
Unless you’re rolling out a single solar panel to simply trickle charge your house batteries, odds are that you need a solar charge controller. This underappreciated piece of equipment is necessary to get the maximum efficiency out of an array of solar panels. It protects all the equipment downstream you’re trying to power and charge, too. We’ll explain the ins and outs of solar charge controller technology.
We’ll share our top picks for those searching for solar charge controllers and provide a buying guide so you can select the ideal unit for your situation. This will help you identify the best solar charge controller for your particular application.
Top 3 Best Rated Solar Charge Controllers - Comparison
4.7 out of 5
4.6 out of 5
4.5 out of 5
Here are the Top 11 Best RV Solar Charge Controllers Full Reviews
Different people have different needs. Some need to power a modest household from renewable energy, while others only want the occasional topping off of RV batteries. Some use a network of small solar panels while others rely on a large array of solar panels that are exactly the same.
These differences explain why we can’t just give you a single best solar charge controller for RV owners.
01) HQST Brand 30 Amp 12V/24V PWM Solar Panel Regulator Charge Controller
Editor Rating: 4.6 out of 5
This solar charge controller and regulator by HQST has a number of points in its favor. It comes with an LCD screen so that you can monitor system performance. While it is a cheaper than average unit, it has enough built-in intelligence to adjust its performance based on the temperature.
This eliminates the risk that the unit accidentally burns out devices because system performance changes as the temperatures fall. You can reset the parameters, too, manually. It is designed for charging smart devices. This starts with the USB port for charging smart phones and other smart devices.
It continues through the high power quality it provides, minimizing the chance that power fluctuations damage expensive electronics. It can deliver both 12 and 24 volts, so you can use it to charge house batteries, as well.
The unit comes with a number of protective features. It has overcharge and over-discharge protection. It has short circuit and reverse connection protection. It can even turn off the light in the LCD screen when it is bright out, saving power. The unit’s lower price results in it wearing out faster than average. For example, the load switch often dies after six months of continual use.
Another issue is the low input voltage. The box says it can handle 55 volts DC max input voltage from the solar panels. However, the company says that it shouldn’t get more than 25 volts DC.
This means that many people accidentally burn out the solar charge controller because they think it can handle twice as much power.
- Excellent power quality safe for recharging smart devices
- Accepts half the input voltage labeled on the box
- Won’t last more than a year unless rarely used
02) Victron Brand SmartSolar MPPT Charge Controller, 75 Volts, 15 Amps
Editor Rating: 4.5 out of 5
This is a higher capacity solar panel charge controller. This charge controller is smart enough to stop charging if your battery hits a defined voltage. It is only has built-in charging profiles for gel and spiral AGM batteries.
However, you can use custom settings to charge flat plate AGM batteries in addition to the more conventional lead-acid batteries. This is one of the few solar charge controllers that can charge almost any type of battery.
The unit has a built-in Bluetooth connection so you can monitor and manage the solar charge controller via your smartphone. However, the Bluetooth may not be recognized by iPhones.
Firmware updates to the controller or operating system updates to your phone can often resolve this problem. However, the Bluetooth range is at most 20 feet no matter what device you use. Conversely, it tracks performance like voltage and currents on all inputs and outputs. It can even email the history log to your device.
What's the downgrades here?
One problem with this model is that they say it can handle 75 volts and 15 amps. However, the power switches are rated for 75 volts maximum, and the de-rated voltage is lower than this. Connect it to 75 volt incoming power, and you’ll trip the limit switches and cause things to fail.
It is really a 60 volt solar charge controller. The solution would have been for the engineers to design it with more safety margin so that you don’t get a shorted out solar charging controller and no protection for your batteries.
This unit does not have a USB port to connect to the controller’s brain or charge devices that connect via USB cables. It uses screw terminals to attach batteries to the solar controller.
03) EPEVER Brand MPPT Solar Charge Controller 30A 12V/24V
Editor Rating: 4.5 out of 5
This solar charge controller is the first on our list specifically designed to handle lead-acid batteries. Other solar chargers on our list can handle these, but the EPEVER is the best solar charge controller for RV owners who just want to recharge a bank of lead-acid batteries via solar panels.
You’d simply do so in the 12 volt mode with the right profile. It can charge sealed, gel, flooded and lithium batteries. It can even be set to handle deep cycle batteries.
The four stage battery charging allows you to safely quick-charge a battery for immediate use. Or you can slowly charge it to 100 percent.
This solar charge controller is incredibly efficient. It can hit 99.5 percent efficiency, but it is regularly delivering 98 percent efficiency.
This is important when you have solar panels with varying voltages or performance connected into one personal power grid.
The EPEVER MPPT solar charge controller comes with every safety feature imaginable. It has over-charging and over-discharging protect. It has standard overload and short circuit protection. It protects against reverse polarity and reverse current. It will protect the battery from being over-charged by the solar panels and a discharge originating from the loads.
One side benefit of the system is that it can automatically identify whether you’re working with a 12 volt or 24 volt DC system. It does this while being middle of the pack in terms of price.The unit can display its current performance on a built-in LCD screen. You can track performance via a smartphone app and PC software, too.
In this item, got some issues
One of the few complaints is that the software takes a little while to generate data. You may be waiting one to three minutes for performance data.
Another issue is the max output. That level is sometimes lower than what is rated. And this is despite the system receiving maximum input power.
Fortunately, this solar charge controller does not have issues with real maximum input voltage being somewhat lower than advertised.
- Doesn’t always hit the max output that’s promised no matter how much power goes in
04) ALLPOWERS Brand 20A Solar Charger Controller Solar Panel Battery Regulator
Editor Rating: 4.5 out of 5
This solar charge controller automatically detects whether you have 12 or 24 volt systems and adjusts the power system settings.
It can charge two different devices via USB ports. It is an ideal choice if you’re trying to charge multiple devices that rely on USB plugs to be recharged. And it is smart enough to send exactly the amount of power required to each device.
It has three stage charging, making it a great choice whether you’re charging batteries that are depleted or topping off their charge.
Every port has several types of protection. It has over-current and short-circuit protection. These are standard features. They have inverse current protection and over-charge protection.
This model is unusual for having inverse connection protection. It is much better than average at overall heat dissipation. You won’t have the solar charge controller shut down because it got too hot. However, the manufacturer still recommends protecting the solar charge controller from the hot sun.
This unit is easier to use than average. You can see the current status on the LCD screen and switch modes as you swap out devices. You simply change modes when swapping out gel cell batteries with sealed lead-acid batteries. It can handle flood / open style batteries.
Few solar charge controllers are designed to handle flood type batteries where you add extra water to it to top it off. Yet this is the common type of battery in older solar panel systems.
In Allpowers, have few little issues
The biggest complaint is how hard it is to connect wires to the solar charge controller itself. It can be hard to connect wires to the controller, and the wires don’t do a good job of holding connected wires in place.
The charge controller sometimes malfunctions by overcharging, and it is difficult to troubleshoot when this happens.
- Difficulty of wiring
05) PowMr Brand 40A Solar Charge Controller
Editor Rating: 4.5 out of 5
This 40 amp solar charge controller can support both 24 and 12 volt systems. It has both an LCD display for adjusting the parameters and a simpler on/off switch.
The 4 stage charging can fast-charge a battery, slowly but completely charge it, and maintain its charge. This will maintain the battery level without burning it out or shortening its life.
The unit can work with lead-acid batteries, AGM batteries and gel batteries. It can also charge two at once. It comes with dual USB charging ports.
You could provide power to tablet PCs, mobile phones and other devices that require 5 volt power. This is the best RV solar charge controller for charging a cell phone and house batteries at the same time.
The unit has a variety of built in protections. It has standard over and under voltage protection. It has under-voltage discharge, open circuit and short circuit protections. It is notable for having over-heating protection, as well. This unit weighs less than 0.7 pounds, so it is one of the lighter models on our list.
One of the downsides is how limited the display screen is. It tells you the voltage but not amps or amp hours. That’s a minor annoyance. The greater problem is how hard it is to flip between battery-charging profiles, something that’s essential to not blow up a delicate battery.
For example, settings that work on a traditional lead acid battery could cause problems with a gel battery.
Other cases for PowMr controller
In other cases, the screen burns out. Now you can’t see what mode it is in. In rare cases, the buttons themselves break. Now you can’t switch charging modes.
Another problem is that it doesn’t always switch between settings automatically. In these cases, it fully charges the battery but doesn’t switch to float mode. This can kill a battery.
06) Sunix Brand 20 Amp 12V/24V Solar Charge Controller
Editor Rating: 4.2 out of 5
This charge controller has a charge current and discharge current of 20 amps. It can handle both 12 and 24 volt batteries. It can be used to recharge house batteries and smart electronics.
However, this cannot be used to safely recharge AGM or gel batteries; you can’t choose a charging profile to safely recharge these types of batteries. It is really only meant for lead acid batteries.
This charge controller is incredibly intelligent. It comes with a wide array of safety features. It not only has over-load and over-charging protection, short-circuit protection and reverse polarity protection, it even has lightning protection.
The unit is intelligent enough to automatically read out your operating voltage. It has pretty good efficiency given its price range and for a PWM charge controller.
This unit is one of the easiest on our list to hook up. And that doesn’t take the USB plugs into account. That’s almost a necessity given how hard it is to read the instructions.
At eight ounces, it is one of the lightest charge controllers on our list.
Performance is neither good nor bad. It works well for a year or so. Then the loading regulators start to fail. Soon thereafter, it stops working. Then it neither offers protection to electronics downstream, and you can’t even charge through the controller.
A few people report that it stops working after only a few weeks. The odds of such failures are higher once the display screen goes dark.
- Modest operating life
07) MidNite Solar Brand CLASSIC 150 Charge Controller
Editor Rating: 4.5 out of 5
The first thing to know about this unit is that it can handle 150 volts and has a maximum current out of 96 amps. This is the highest capacity solar charge controller on our list. It can handle a 1000 Watt 24 volt solar panel or a 900 Watt wind turbine, though not both at the same time.
However, it cannot convert 24 volt solar power to 12 volt power; you’ll have to buy a separate step-down converter.
Be very careful about connecting a dozen 100 watt solar panels in series, because that could overwhelm the maximum input voltage of the solar controller.
You could run them in two groups connected in series and connect the two in parallel, but even then, you need to be careful. This solar charge controller is best used with large, stand-alone, high capacity solar panel arrays.
This unit is packed with features. You can control it via wi-fi. It can also be monitored via an Android app. It even maintains a four month data log. This model also has a decent LCD screen, something the “lite” version of this solar charger by the same manufacturer lacks.
This is an MPPT charge controller. It offers real four stage charging, great for whether you’re fast charging a deep cycle battery or topping off the house batteries. It can also charge several batteries at once.
What are the downsides for MidNite controller?
What’s the downside? For one, the price. You can literally buy half a dozen or more of most other solar charge controllers on this list for the price of a single Midnight Solar charge controller. Another issue is the intelligence built into it.
It is bleeding edge tech, but this means people sometimes have to update the firmware for it to work. This is a common fix when you’re adding temperature sensors or trying to manage the charge controller via the remote control.
In other cases, the software errors out and resets to zero, wiping out data on how much solar power was collected that day and relayed to the batteries.
Another issue is how hot the system gets. It lacks the excellent heat dissipation of other solar charge controllers on our list. Don’t put it in direct sunlight on a hot day or it will overheat.
The manufacturer brags that the terminals are rated for 75 degrees C. That doesn’t prevent the control board from overheating to the point the software glitches out.
08) Blue Sky Model SB3000i Solar Boost MPPT Charge Controller
Editor Rating: 4.4 out of 5
This is a versatile MPPT solar charge controller. It has a voltage step-down controller that allows you to use high voltage grid-tie solar cells at up to 22 amps of output current. It can handle up to 30 amps from 36 cell 12 volt solar panels. This unit is middle of the pack in terms of price.
It can charge almost any type of battery. It can handle flooded batteries, gel batteries and AGM batteries. This is the best solar power charger for those who want to recharge lithium batteries, because it is one of the few models safely designed to do so, making it one of the rare lithium compatible solar controller/chargers on our list.
It has no problems recharging deep cycle batteries like those used on boats, too. It can full charge them, equalize the charge and top them off.
This is the best RV solar charge controller for those who need to charge everything from lithium to lead-acid flooded batteries. The LED display is quite readable. It uses relatively little power in the night-time dim mode, but you can turn the LED display off, too.
The unit is smart enough to connect with other charge controllers by Blue Sky Energy to create an intelligent power grid. This makes it a good choice for industrial use or large-scale off-the-grid renewable power production for individuals. It lets you build your very own internet-of-things.
Is there any downgrade issue?
This model is unusual because of the flush mounting with wire connections. This allows you to connect wires without them hanging where they could be caught and accidentally pulled out. It has basic protections like overload protection and reverse battery protection. It also offers panel protection.
One issue with this solar charge controller is that it often overheats though it is well within the rated current. This is despite the MPPT controller being incredibly efficient compared to other technologies.
The manufacturer offers a wall-mount box, but that’s separate and costs extra.
09) WindyNation Brand Model P20L LCD 20A PWM Solar Panel Regulator
Editor Rating: 4.4 out of 5
This solar charge controller works with both 12 volt and 24 volt batteries. More importantly, it can work with AGM, traditional lead acid and general gel batteries.
The only type it isn’t explicitly rated for is lithium ion batteries. It has a variety of protective mechanisms in place.
It has the standard overload and short circuit protection plus reverse polarity protection. It takes overheating protection to the next level with its battery temperature sensor. Unlike other solar charging controllers, it will actually put the reading from the battery temperature sensor on the control panel.
The LCD screen shows the current state of the charge controller, though it does not show the remaining battery life. You can adjust the settings by flipping through the modes.
The unit is both programmable and easy to use. If you make a mistake, it reverse to its defaults. For a PWM solar regulator, it has moderately good conversion efficiency. "Only MPPT models beat it in that regard."
Here are few downgrade issues too
One issue is the discrepancies between labeling and functionality. Some sources sell it as a 30 amp solar controller while others warn it can only handle 20 amps.
Realistically, consider it a 20 amp charge controller. This solar charge controller often gives out after a few months of heavy use. It regularly dies after a year of intermittent use.
If you’re lucky, it is only the display screen that dies and stops responding. If you’re unlucky, it stops regulating voltage altogether and your batteries blow up because it isn’t monitoring or controlling the voltage level.
This is because the low voltage cut off sometimes quits.
10) Renogy Wanderer Model 30 Amp 12V Solar Charge Controller
Editor Rating: 4.3 out of 5
This is an above-average 30 amp, 12 volt solar charge controller. The pre-drilled holes make it easier than average to install in an RV.
This battery charge controller is compatible with sealed, gel and traditional flooded batteries. It is not considered lithium-compatible.
Notably, it is compatible with any negative ground system. The terminals themselves are average, but you are connecting wires to them. No USB plugs here.
This solar charge controller is smart enough to adjust for the outside temperature, nearly guaranteeing your batteries won’t be overloaded when temperatures drop.
It is plug and play with the Wanderer brand temperature sensor, though those are optional and sold separately. This is the best RV solar charge controller for those who own other Wanderer and Renology hardware.
The PWM charge controller is more efficient than the average PWM solar battery regulator. It offers four stage charging. Whether you need to quickly charge a battery to 80 percent, fully charge a deep cycle battery, maintain a partially depleted battery or keep a battery at full power, it can do the job.
The unit has a number of built-in safety features. It has standard protections against over-charging and overload. It has conventional protections like short-circuit protection and over-discharging protection. It also protects against reverse polarity.
This solar charge controller has one of the widest working temperature ranges we’ve seen. It is rated to work at -20 F up to 133 degrees F. It can also handle wires up to 4 AWG.
Few downsides are here also
The model isn’t perfect. Sometimes the control panel won’t let you switch modes, though it is more likely to error out like a computer in need of a reboot. It isn’t uncommon for it to use the wrong float voltage.
Unfortunately, there is no way to fix this with a firmware patch or operating system update. It lacks UL or CSA certifications, so you can’t legally use it in private homes rented out to others.
11) Go Power! Model GP-PWM-30 30 Amp Solar Regulator
Editor Rating: 4.2 out of 5
This pulse width modulated or PWM solar battery charger can be used with wet cell, gel and ABM batteries. In theory, you can set it on AGM to charge LiPo batteries.
However, they don’t explicitly state that it is lithium ion battery compatible. This means you can probably use it for such but need to exercise caution when doing so.
It can handle up to 510 watts of solar power. That gives it a much higher capacity than most of the solar charge controllers on our list. It can handle up to 28 volts, but it is best for 12 and 24 volt batteries. It offers four stage battery charging. Aside from recharging deep cycle batteries and conventional batteries, it can “float charge” and equalize batteries.
It's able to charge two batteries at a time
Equalizing the batteries will remove the sulfate crystals that accumulate on battery plates over time, reducing their performance. Better yet, it can charge two different battery banks at the same time. At twelve ounces, it is a little heavier than average but not by much. It isn’t bulky. If you already owned a GR-25 amp unit or similar Go Power solar controller, this model will fit into your existing panel.
The old screws will fit, too. No need to buy a new cover and box for it to mount it in your RV. The LCD display will show the voltage, the amperage and how full the battery is. Several battery chargers on our list leave off at least one of those values.
However, this unit isn’t giving highly accurate results. It may say a battery is at 20 percent capacity when it is almost zero. Because of incorrect readings like this, it will sometimes fail to completely charge the batteries.
What is the Best Solar Charge Controller for RV?
Any charge controller limits the rate at which electric current is sent to or pulled from batteries. A solar charge controller is simply a charge controller designed to stand between solar panel arrays and the batteries and inverters they’re charging. Depending on the solar charge controller, it may prevent deep discharging of the battery or even reverse sulfate buildup in the battery. Charge controllers may be stand-alone devices, integrated inside of a battery pack, a battery powered device or a battery charger.
Solar charge controllers are, at a minimum, regulators for your solar battery that are bought as stand-alone devices plugged into network between the battery and solar panels. They usually prevent the battery from being overcharged. You don’t want that to happen, since exceeding the voltage capacity for the battery will damage it until it can no longer function. Solar charge controllers typically regulate the current, too.
A few models will monitor battery temperatures, too, and turn off power when it is overheating.
Are Charge Controllers Essential for RVers?
Charge controllers are essential if you’re trying to set up an off-grid solar system. This includes solar panels to recharge house batteries in an RV and off-the-grid power for your cabin. However, you still need to do your research to find the best solar charge controller for RV use.
Solar charge controllers aren’t necessary if you’re only going to use solar panels while connected to the power grid. In these cases, the excess power is directed to the power grid. Nor do you need a solar charge controller if using trickle charge panels. Those are in the one to five watt range. If the panels are generating two watts or less of power, you really don’t need a solar charge controller.
How does a solar charge controller work?
A solar charge controller is not an inverter. It won’t store up extra power as a de facto battery, and it won’t guarantee a certain level of power quality. It simply regulates the flow of power from the solar panels “downstream” to your battery, inverter and any other devices. But how does a solar charge controller work?
At the most basic level, it will kill power flow to your battery if some cut-off level is reached. Too much voltage or too much current will cause the controller to disconnect the battery to protect it. If you have a shunt controller or more advanced system, it may send excess power to another battery, a water heater or some other designated secondary destination.
Solar charge controller often have other safety measures built in such as preventing reverse current hurting the solar panels. That’s often due to discharge from the batteries while the solar panels themselves are dead due to the dark. If you have wind or hydro power set up, those may cause reverse power flow, too.
To protect the battery, the relay switches off, disconnecting the battery. Depending on how smart the controller is, it may or may not switch the relay back when voltage and current levels are safe for the battery again. Alternatively, a blocking diode may be sued for the same purpose.
Are there advanced units for easy use?
More advanced units have an LED screen that shows you system efficiency, how much power is flowing through the system and performance metrics like temperatures and battery voltage.
The most important job of the charge controller is regulating the voltage flowing to the battery. It will certainly prevent too little voltage reaching the battery. However, they may also modify power flow to prevent too little voltage from reaching the battery, too. Simpler charge controllers only turn the power flow on and off, while more advanced models can modify the charge level.
Difference Types Of Solar Charge Controllers
Shunt regulators are the simplest type of charge controller. These typically rely on shunt transistors to protect the battery. They will simply short out or disconnect the solar panel if a certain voltage level is hit. These types of solar charge controllers are only found in old solar panel arrays or very cheap ones.
The only points in their favor are very low cost and reliability. They are so simple that there is almost thing that can break. The downside is that when it burns out, you’re without a charge controller until you replace the transistors or buy a new controller.
More advanced (and expensive) units can resume power flow once voltage levels drop to an acceptable level. More advanced shut controllers may be able to shunt extra power to an auxiliary load like a water heater when the batteries are full.
02. Series regulator
A series regulator is a type of charge controller. It will stop current flow to batteries when they are full. A series regulator is very different from a shunt charge controller that sense excess power to a secondary source when the batteries are full.
One benefit of series regulators is that they’re simple and reliable. These are a suitable solar charge controller for RV use if you just want the protection of a controller instead of hoping the battery can prevent burnout on its own.
03. PWM regulator
PWM stands for pulse width modulation. They are a simpler technology, and that makes them cheaper than MPPT charge controllers. PWM controllers are really only an option if your solar panels and batteries have the same voltage. PWM charge controllers are often called three stage controllers. They’ve become the industry standard, though simpler one and two stage controllers that rely on shunt transistors and relays still exist.
PWM controllers are generally better for small do-it-yourself solar panel arrays that can trickle charge batteries or power smaller devices like lights and radios. For example, a small 5 watt solar panel paired with a battery could be protected with a PWM controller.
However, if you have multiple small 5 watt panels, you’d want an MPPT charge controller. This makes a PMW type the best solar charge controller for RV use if you are trying to connect half a dozen little solar panels to recharge house batteries.
How does a PWM charge controller work?
A PWM battery is able to reduce current gradually, modulating the pulse width, hence the name. This is in contrast to traditional charge controllers simply turning the power on and off. Many PWM charge controllers will sense when a battery is getting full and drop the voltage. This will “top off” the battery while lowering the risk it over-charges.
This is at a minimum two stage charging but could include four or five charge levels. A trickle charge will keep a battery topped off but minimize stress to the battery and water loss.
How many sizes are there in a PWM charge controller?
The most common sizes of PWM charge controllers are 12, 24 and 48 volts. Amperage ratings can be anywhere from one amp to sixty amps. Select the solar charge controller that meets the highest variable your system needs.
For example, if your solar panels put out 12 volts and 16 amps, the solar charge controller must be able to support 16 amps. You actually want to take the base amperage produced by the system and multiply by 25 percent so that the system can handle spikes due to light reflection.
That would mean the best solar charge controller in your case is a system that handles 20 amps though the general load is 16 amps. A 12 volt system is a minimum in this case, but 24 volts can work, too, though it won’t be as efficient.
04. MPPT charge controller
MPPT stands for maximum power point tracking. An MPPT controller is the only solution for getting full power out of group of high voltage solar panels. For comparison, standard controllers will work if the maximum input voltage isn’t exceeded, but you’ll lose anywhere from twenty to forty percent of the power the panels produce.
For example, your 175 watt solar panel will be limited so that it can only send 90 watts to the battery unless you’re using a solar charge controller designed for this particular situation. By increasing power delivery ten to thirty percent, you could be able to meet your needs with fewer solar panels.
Or you could use a 150 volt solar panel array to charge a 24 volt battery. Higher array voltage passing through an MPPT charge controller results in a lower charge current; this can reduce your wiring requirements. MPPT solar charge controllers are essential if you’re dealing with unusual voltage ratings like 56 volts.
MPPT charge controllers can be considered the top of the line, the most advanced technology available in solar charge controllers. They are notable for their high efficiencies, often approaching 98 percent.
What are the Greatest benefits of MPPT controllers?
The greatest benefit of MPPT controllers is that they can be used when the voltage of the batteries and solar panels don’t match. This is worth the cost if you’re trying to connect several smaller panels in addition to one large solar panel array.
The size of the MMPT charge controller almost doesn’t matter as long as it can handle the maximum load coming off the solar panels. MPPT controllers allow you to utilize almost all the power coming off your solar panels. This maximizes the efficiency of the solar panel array. It certainly eliminates the waste you’d see when sending solar power to a lower voltage battery bank.
The Main Benefits of MPPT Charge Controllers are _
- Maximizes power conversion efficiency with multiple panels
- Can handle unusual voltage outputs from solar panels
- Can connect and manage multiple, disparate solar panels in one network
How does a MPPT charge controller work?
MPPT charge controllers are not really 4 stage controllers; they’re simply called this to make them seem like the next step up from 3 stage PMW charge controllers. MPPT charge controllers monitor the charge of the battery and alter the power delivery to the battery as it reaches capacity.
However, they’ll also alter the flow of power across the network to maximize power delivery. Yet they’ll always burn out when the upper voltage limit is hit, though that upper voltage limit depends on the model you select.
How many sizes are there in a MPPT charge controller?
The smallest solar charge controllers have around five amps of control. The most common size of MPPT controllers are 60 to 80 amps. If the currents are over 60 amps, you’ll probably be advised to connect two or more 40 to 80 amp charge controllers in parallel.
The most powerful solar charge controllers, all of them MPPT controls, go up to 80 amps.
Things to Consider for Purchasing the Right MPPT Charge Controller
01. Type (MPPT or PMW model)
PMW solar charge controllers can be considered two level charge controllers, while MPPT charge controllers are three or four level. They can adjust to more operating conditions.
If you’re using a shunt or PWM charge controller, it must match the entire system voltage – both that of the solar panels and the batteries. MPPT charge controllers can handle mismatches in capacity and varying outputs from multiple solar panels.
PMW charge controllers can work with high voltage solar panels if the maximum input voltage of the charge controller isn’t exceeded. However, a lot of power is lost in the conversion process. This could be anywhere from twenty to sixty percent.
MPPT charge controllers are the best way to maximize how much power are actually able to use. MPPT charge controllers should be your choice if the solar panels put out more than 200 watts.
02. Battery Voltage
Solar charge controllers can be sized both based on the amperage and the voltage. The standard voltage sizes are 12 volts, 24 volts and 48 volts DC. Because these are the standard battery bank voltages, inverters are typically offered in these voltages – and solar charge controllers are, too.
03. Max Input Voltage
The solar panels should come with a notice of how much voltage they can put out. For example, a 200 watt solar panel system will typically put out 12 volts. Recognize that it could put out anywhere from 10 to 17 volts.
A solar charge controller cannot handle more power than the input voltage it is designed for, and this is the power that will be coming out of the solar panels. This value will be listed among the design specifications. You should choose a power controller with a max input voltage somewhat higher than the max the solar panels will put out.
Note that the open circuit voltage of solar panels goes up as the temperature drops. This means that you need to verify that the controller’s input voltage ratings will handle the solar panels’ power output when it is very cold. They may not give you much information except a warning not to use the controller when temperatures are below a certain point.
What's the Basic formula for sizing?
A basic formula for sizing the charge controller is to take the short circuit current or lsc from the solar panel array and multiply that value by 1.56. This gives you the minimum number of amps the solar charge controller must be able to handle. The current at maximum power or lmp value is always lower than the lsc.
Charge controllers should be able to handle unusual conditions that can cause a power surge. You can account for this with a 1.25 derating factor. You can find this by multiplying the module Isc by 1.25 to get the minimum charge controller amperage the solar charge controller should be able to provide.
04. Max Current Output
The output from solar modules will vary based on sunlight intensity and temperature. The charge controller has to manage the variations in power sent downstream, since a current that’s too high will damage a battery and one too low can affect any electronics plugged into it.
05. Item Price/Cost
Price is always going to be a determining factor, but it cannot be the only one. For example, very simple charge controllers simply burn out a fuse or transistor when voltage or amperage is too high. You’ve protected the battery connected downstream, but you can’t reset it. You can only replace it.
In better, somewhat more expensive units, it may automatically reset the connection when voltage or amperage is within acceptable standards. Or it may shut excess power to a hot water heater or other system, preventing the waste of that energy without damaging anything.
06. Extra Features
MPPT solar charges may come with additional features that are useful or beneficial in the right circumstances. For example, relatively few models will automatically turn off DC powered loads. A solar charge controller for RV that lets you turn off power draws as well as prevent power being pulled from the batteries to the solar panels where there is no sunlight is worth it, if you don’t want to have to micromanage the power grid.
A smart device is useful if you’re micromanaging a complex power grid, such as when you’re trying to optimize power output from half a dozen different solar panels with varying voltages.
MPPT controllers monitor battery's voltage
Some MPPT charge controllers can monitor your battery’s voltage and track performance of individual solar panels. A few will even feed that data to your home network or smartphone. This makes it easier to micromanage your renewable power grid. This isn’t necessary if you have a four solar panel set connected to a basic solar power controller or use a single low power solar panel trickle charging a device.
Additional protective features are always a plus. For example, you want units with general fault protection and arc fault protection. Charge controllers that will turn off when a battery is overheating add an extra layer of protection for your batteries.
If you’re using an unusually sized solar panel in terms of power output, you should use an MPPT solar charger so that it can handle the unusual capacity.
Frequently Asked Questions for Solar Charge Controllers
01.How long will the best Solar Charge Controller last?
If you mismatch the voltage or amperage coming off the solar panels to the solar charge controller, you’ll burn out the charge controller almost immediately after setting it up. Whether it works after you flip a switch or replace a relay depends on the model.
As long as nothing burns out, the unit can last for years.
With a smarter MPPT unit, software updates may be required to keep it working properly, especially if it is controlled by an app or logs data sent to your computer.
02.How to maintain an RV Solar Charge Controller
Your solar panels themselves require regular maintenance. They need to be cleaned so that sunlight can reach them. They should be covered and protected from hail and flying debris. But how do you maintain the RV solar charge controller? The average solar charge controller doesn’t really need maintenance unless it is damaged, such as when a fuse burns out. You do need to check the fasteners and mounts to make sure they’re tight.
This is because vibration and thermal expansion and contraction can loosen them over time. Loose connections cost you, because part of the power is lost and turns into heat. You can clean the connections with non-abrasive cleaner, and this may be necessary if they’re grimy.
03. Which types of solar charge controller are the most widely used?
In older systems, the PWM or pulse width modulated systems are extremely common. They have become the industry standard, the minimum you find even in cheap solar panel kits. The MPPT solar charge controller determines the best working amperage and voltage of the solar panel array and matches this to the battery bank.
This results in ten to thirty percent more power delivered to the batteries. MPPT solar charge controllers are the most common choice for solar systems over 200 watts, because of the extra power it yields.
The MPPT solar charge controllers are also commonly used for such solar panel arrays because you’re already spending so much on the solar panels that a little more for a better solar charger is worth it.
04. What happens when RVer connect higher voltage panel to a non-MPPT charge controller?
If you use multiple PWM charge controllers with the same battery bank, you may be able to handle the output of the large solar array. They must be connected to each other with communication cables and set up to work in unison. Most people don’t have the technical skill to do this.
What happens if you connect a higher voltage panel to a non-MPPT charge controller? You will at a minimum lose a lot of power as the charge controller lowers it to the output voltage it can deliver. This could cost you 20 to 60 percent of the power coming from the solar panels. There is a fair chance you’ll trip various safety devices like over-voltage and over-temperature controls.
In a worst case scenario, you’ll burn out fuses, relays and other protective components and permanently ruin the charge controller.
05. Do Rvers always need a solar charge controller?
If you have a little portable solar panel that can trickle charge your cell phone battery if left out all day, the answer is no. If you have a single solar panel that feeds your inverter before recharging the house battery or smart devices, the answer is no.
A solar charge controller is really only necessary when you’re connecting a variety of solar panels and/or a high wattage system.
06. Which solar charge controller is the best? PWM or MPPT?
MPPT solar charge controllers are best if you are pulling in more than 200 Watts of solar power. MPPT solar charge controllers are the ideal choice if you’re using non-standard solar panels putting out 40 or 56 Watts, especially in combination with other sizes. The MPPT is smart enough to capture the power from the out of spec unit, maximizing power sent downstream.
In every other situation, a PWM solar charge controller is the better choice. This is because most people are using a standardized array of solar panels and keeping power usage to a minimum. The PWM then wins on the price versus features argument, because you don’t need the extra intelligence of the MPPT.
Do your research regarding safety features, and you could find a PWM solar charge controller with under-voltage, reverse polarity and other safety features that used to be limited to the more expensive MPPT charge controllers.
Remember that the best solar charge controller for you is the one that meets your power system needs at a reasonable price, not the most expensive or intelligent system.
07. Is the MPPT charge controller always better?
The answer is no. MPPT charge controllers typically cost more, and they are often more than what many RVers need. MPPT is better when you’re connecting a variety of solar panels that have very different specifications.
MPPT solar charge controllers are necessary when you have scattered solar panels that will produce very different power levels. And MPPT solar charge controllers are necessary when you are generating 200 plus watts of power.
08. What features does a charge controller offer additionally?
It's another important question that we get from users regularly. We're going to explain them one by one below. Because there are many essential features that needs for an RV solar charge controller. See ahead_
A. Load terminal
A ground fault circuit interrupter or GFCI outlet has two different terminals, a line terminal and a load terminal. When you connect only to the line terminals, the outlet has ground fault protection for itself.
Connect the power plug or wires to both the line and load terminals, and the outlet protects itself and any devices downstream on the same electrical protection.
This means that a solar charge controller with a load terminal can offer GFCI protection to devices connected to it, if they’re connected properly.
B. LED Indicators
LED indicators are incredibly beneficial. You know at a glance when something is wrong due to the red or blinking LED indicators. You don’t have to get up and go look at the wiring and connecting hardware periodically to monitor it. Nor do you have to worry about missing an automated warning sent to your app because there’s no wifi in the area.
The LED indicators are so obvious that someone who isn’t familiar with the system can still warn you that it went from green to red or the warning light is flashing.
C. LCD Display
An LCD display has a number of benefits, assuming the display itself is good enough to be easily read. You don’t have to try to figure out if the battery or voltage level is right at the limit or barely under. You’ll be shown the actual reading along with warnings if necessary.
In smarter charge controllers, you’ll be told how much power is coming in from the various solar panels as well as what is going out of the solar charge controller.
The best solar charge controller will give you the information you need to fix wiring or clean solar panels to see the full potential of your solar power system.
D. Remote Display
A remote display can take several forms. Some solar charge controllers have software that act as a de facto dashboard, telling you the state of your solar panel system.
Other solar charge controllers have combination remote controls and screens to let you adjust parameters, monitor the device’s function and turn things off.
09. How many Modes are there in a charge controller?
How many modes a charge controller offers depends on the model you choose. Most charge controllers offer three or four modes, especially MPPT and smarter charge controllers. What are some of the most commonly available modes in charge controllers and battery chargers?
A. Equalization Mode
Traditional lead acid batteries lose water from the cells as they discharge power, while recharging them puts the water back in. This process is repeated as the batteries are recharged regularly, but it isn’t 100 percent efficient. You can get a build-up of sulfate on the batteries. In a worst case scenario, a near total discharge and staying in that state alters the battery chemistry to the point it can never fully recharge again. The solution is to “equalize” the battery.
In equalization mode, the voltage is raised to 15.5 volts and maintained for two to three hours. This is the equivalent to overflowing a water bucket to wash away the debris, cleaning it. The act of equalizing the battery will also reverse acid stratification, where the acid is denser at the bottom of the battery. The battery voltage is then dropped to normal, while the solar charge controller will go into float mode.
Note that sealed or maintenance free batteries do not need equalization. In fact, setting the charge controller to equalize them can cause them to catch fire or explode. The excess voltage causes the electrolyte to bubble as it is heated up. While this cleans the plates inside the battery, it also generates pressure. In the case of sealed batteries, the excess pressure can’t be vented. This is why the batteries will often explode.
Note that an over-filled lead acid battery that can’t vent enough excess hydrogen gas could explode if you try to equalize it, too. And never try to equalize a battery that recently, literally froze.
B. Boost Mode
Boost charging, also called fast charging, is when the charger sends a high current to the battery for a short period of time. It is done to quickly charge depleted batteries. However, it isn’t very efficient. It may take a nearly dead battery and get it up to 70 or 80 percent capacity as possible.
However, it will rarely charge a battery to 100 percent. In fact, many charge controllers will stop a ways before the battery is 100 percent charged so that it doesn’t damage the battery (or cause it to explode) by charging it quickly to capacity and beyond.
C. Float Mode
Float charging, also known as trickle charging, charges the battery at a reduced voltage because there isn’t much power that needs to be sent to the battery. Float charging is generally used when the battery is rarely discharged. It may also be used when the battery has been fully recharged and is being maintained at 100 percent power. A battery that has undergone boost charging may then be switched to float charging so that the battery is gently topped off.
Note that not every battery charger has the intelligence to detect the battery current and reduce the charging voltage. Float charging is typically found in “smart” chargers, four stage battery chargers, and four in one chargers.
D. Low Mode
Trickle charging or low mode is almost the opposite of boost mode in a battery charger. It sends power at low amperage, so you can leave the charger on for a long time without the risk of over-charging the battery. Smart trickle chargers and smart general solar charge controllers can detect the charge level and automatically adjust the amperage. This then prevents the battery from over-heating or off-gassing.
Note that a low mode from a battery charger is not the same thing as accidentally trickle charging batteries because the solar panels aren't producing much power.
The best solar charge controllers will handle the batteries and connect seamlessly with the solar panels you already own. We’ve provided our recommended list of solar charge controllers and given you a buying guide so that you can select the best solar charge controller for your particular situation.