Why you need a solar charge controller
As you might have guessed from their name, a charge controller is just that, a controller, or a regulator. This regulator is designed to keep your solar battery from overcharging. Since batteries are only rated for a certain voltage capacity, you do not want to exceed that. If you do, that can lead to permanent damage and loss of function over time. Since these batteries are usually very expensive, you want to make sure that they last as long as possible. A solar charge controller helps to make sure that damage doesn’t occur from overloading the battery.
Charge controllers are not necessary for every solar system, however. If, for instance, you are installing a solar system on your home, but will remain connected to the electrical grid infrastructure from your power company, you will not need a charge controller. In this instance, once your home’s battery is full, the extra electricity will be funneled back to the grid, which will keep your battery from becoming damaged.
If, however, you are going to install an off-grid solar array, then you are going to need a controller. An example of this system would be an off the grid cabin, RV, or boat. Since these systems are not connected to the electrical grid and will have nowhere to go with the excess energy created by the solar panels, you will need to get a charge controller to keep your batteries safe and functioning properly.
Features to consider when choosing a solar charge controller
It should come as no surprise that when it comes to choosing a new solar charge controller, there are a lot of different factors that need to be considered. In this section, we will guide you through these aspects in detail, so that you can make an informed decision when you are ready to buy.
MPPT or PWM?
When it comes to finding your new solar charge controller, the first thing that you need to determine is what type of controller you want. There are two different options to choose from, which include PWM, or Pulse Width Modulation, or Maximum Power Point Tracking, also known as MPPT. These two types are both effective but are better suited to different types of arrays. You need to make sure you understand your system’s power capabilities before you make your final decision as to which type to purchase, as both systems have their pros and cons in different applications.
- PWM – Pulse Width Modulation solar charge controllers are the most common type of charge controller available to consumers. They are a much simpler system than MPPT models, which helps to make them much less expensive. It does, however, limit their effectiveness on larger solar arrays. Basically, these controllers work by slowing down the amount of power going into the battery as it approaches its capacity. When the battery is completely full, these controllers allow a small amount of power to come into the battery, which allows it to constantly remain full without overdoing it. These controllers require that the solar panel system and the battery have the same voltage, which is usually the case for smaller setups, but not usually true for larger systems. PWM controllers are also more affected by the weather than MPPT models, as they begin to lose efficiency if they are too hot or too cold.
- MPPT – MPPT controllers are much more expensive and complex than PWM systems. They work in much the same manner in that they will reduce the amount of power coming into the battery as it begins to fill. However, where they vary quite a bit is that they do not require the solar panels and batteries to have the same voltage. MPPT controllers are designed to adjust their input so that they bring in as much power as possible from your solar array. They are also able to change their output to match the battery. This makes MPPT controllers much more efficient than PWM controllers, as they allow you to utilize the full potential of your solar set up more completely. These controllers are also unaffected by weather. Regardless of how hot or cold it might be outside, they will bring in just as much electrical energy for your setup as they would on a more mild day.
Maximum input power (voltage)
You will also have to figure out exactly how much power your system is going to produce. This is especially important if you are going to be using a PWM controller since this voltage will need to match up with your battery since these controllers are not capable of converting the power input to match the output like an MPPT system. The Renogy Adventurer is a good option if you want a PWM system, as it can handle up to 50 VDC, which is pretty high for this type of controller. It will allow you to charge your batteries at a lower cost. However, you need to be sure that your batteries will match up with your system with a PWM controller like this one.
If you have a larger array that produces a ton of electricity, then you will probably want an MPPT controller like the EPEVER Tracer4215BN. This model can handle up to 520W of input for a 12V battery, or 1040W for 24 volts. You also won’t have to worry as to whether or not your batteries match up to the input since this type of controller will convert the input to match the output.
Maximum power current
The maximum power current is the amount of energy that your solar system and the solar controller can handle flowing through it at one time. The last thing that you want to do is to get a controller that cannot handle all of the electricity that your system is producing since it will be wasted. Basically, for every 100-watt solar panel that you have, you can count on about 6 amps of power during full sun hours. If you have a larger setup, then you will need a controller that can handle a higher maximum power current. On the other hand, if you have a very simple system, then you can probably get by with a controller with a lower maximum current rating.
For instance, if you have a very small setup, then you could go with something along the lines of the GHB Solar Charge Controller. This PWM controller has a lower current rating but will be perfect for smaller systems. If, however, you have a very large system, then you will want to get an MPPT controller like the OOYCYOO MPPT Charge Controller. This controller has a maximum current rating of 40 amps. This means, basically, that it can handle up to 6 100-watt solar panels that are producing 6 amps each without any issue. For even larger setups, the Renogy Rover PG is an awesome option. This model can run at 60 amps, which means it can handle up to 10 100-watt solar panels without any issue at all.
Maximum PV open circuit voltage
The open-circuit voltage, or Voc, is how many volts the solar panels in your array will be able to produce with a load on it. This number can be found when measuring across the plus and minus leads with a voltmeter. This number is very important since it is the maximum amount of voltage that solar panels can produce under standard conditions, which can be used to determine how many solar panels can be wired into a solar charge controller. By making sure that your panels don’t go over your controller’s maximum, you will protect the systems from being damaged.
If you have a smaller array, then you can get by with something like the Renogy Adventurer, which has a Voc or 50 volts. This makes it a great option for single or dual panel systems that are used to power smaller electronics. However, if your array is on the larger side, then you could go with something like the Renogy Rover PG. This model can handle up to 150 volts, which makes it great for arrays that have 6 or more panels.
Dimensions and mounting options
Something else that you will need to keep in mind with your new controller is how much space it will take up. How much these dimensions matter will really depend on where you are going to be using your new controller. If you are, for instance, installing it in a barn, house, or cabin, then you will not have to worry about the size of the system as much as you would if you were putting it into an RV or travel trailer. Since these locations have a much more limited amount of space, you will want to shoot for a smaller model so that it doesn’t take up too much room.
As far as mounting options go, the most common way mount these controllers is on the wall. Many of them have a back panel that gets screwed into the wall, and the controller slides into place. Some of the larger models need to screw into studs, since they have a bit more heft to them, while the smaller options can usually be attached pretty much anywhere without any issue.
Ease of Installation
No matter how you slice it, installing a new solar system is not a job for a novice. Even if you are someone that works on electrical systems regularly, solar systems present a few different challenges that you might not be aware of. As such, it is probably a good idea, unless you are a master electrician, to have someone else install your new solar system and solar charge controller for you. The last thing that you want to do is make a mistake and damage such an expensive system.
Of course, if you are fully committed to completing the installation on your own, then you might want to go for a PWM system. These controllers are a bit less complicated than their MPPT counterparts, which might make them just simple enough for a DIYer to hook up correctly.
There are lots of extra features that you can choose from when it comes to finding a new charge controller for your solar system. The very first, and perhaps, most important extra feature to keep in mind are built-in safety systems. These might include protection against reverse polarity, short-circuit, or overheating. When it comes to electrical systems, there is no such thing as too many precautions. The more safety features a controller has, the better off you will be in the long run.
Another feature that you might want to consider having on your controller are USB ports. As more and more pieces of essential electronics begin to utilize this type of charging port, it only makes sense to add some to your space if possible. That way, you can easily charge your phone, camera, or tablet with ease.
As we mentioned above, these solar charge controllers can be a bit tricky to install. This is especially true if they need to be calibrated to match your solar panels. Thankfully, some models come with a built-in sensor to automatically detect the power output of your system and can align themselves to work correctly right when you start them up. This will save you a bit of time on the installation process and will also make sure your system is running to its full capacity. The Renogy Rover PG is a great example of a model that includes this feature.