After the size and type of solar arrays are decided, it’s crucial to take a careful step while choosing another critical part of your system. The Solar Charge Controller is almost as important as the solar panels themselves.
An excellent solar charge controller will improve the system efficiency while keeping batteries safe. On the other hand, an improper charge controller wastes solar energy. And is likely to damage your battery bank causing thousands of dollars in damages.
What is a Solar Charge Controller
Charge Controllers are installed between solar panels and Battery Banks. As the name suggests, these controllers regulate the incoming power from your solar panels and direct them to batteries and sometimes to the DC load.
An essential task of controllers is to prevent batteries from overcharging, as this can cause severe damage to the batteries.
In addition, most charge controllers are equipped with Overload protection. When the energy produced by the panels is higher than what the system can handle, this feature is essential since overloading can cause multiple issues such as overheating and even fire.
Solar charge controllers are designed to protect batteries from being over-discharged by disconnecting non-critical loads when voltage drops.
How do Charge Controllers regulate the amount of power?
There are two controllers: Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT).
The PWM controllers regulate energy flow from the panels by gradually reducing the current with something called "pulse width modulation.” The PWM transfers energy based on the battery’s state. While efficient, this system works best only with a smaller system with little energy use.
In contrast, a more extensive system will struggle to operate in less ideal conditions. On the other hand, PWM solar charge controllers come with more affordable pricing and their ability to restore deeply discharged batteries.
In contrast, MPPT charge controllers connect to solar panels arranged in high voltage output. These controllers regulate the current transferred to batteries. These controllers are specifically designed to work with more complex and larger systems and increase solar systems' energy yield to up to 90%.
Since the input voltage can increase significantly compared to PWM controllers, an MPPT controller will allow longer cables to transfer the energy from solar panels to batteries.
PWM vs MPPT charge controllers, Which one should I choose?
The first question you need to answer is, “Is it a Large Solar Power System?” If the answer is “Yes”. You most likely need an MPPT solar charge controller as it will provide more stability and efficiency.
Even if you intend to install your system in a van or RV and it will be a small system, PWM will not always be a suitable solution as they are not efficient enough for places that do not benefit from ample sunlight all year round.
So our recommendation is more investment in MPPT solar charge controllers for superior efficiency and more flexibility in designing your solar power system.
How to Size the solar charge controller correctly?
First, Decide on the battery size and solar array output. Choosing solar panels can be difficult at first; however, once you have the correct type of the solar panel in mind, you can divide the total yield of power by each panel wattage and the number of solar panels you need.
Then for batteries, the essential factor is to ensure that the system can have autonomy for 24 hours, at least if solar panels don’t produce anything. And whether you want to have a system that is 12V, 24V or 48V. Most of the newer generation MPPTs can operate with battery types with an output of up to 48V.
To choose the right MPPT, you just need to use Ohm’s law and divide the solar array’s nominal power by battery voltage, and then you have the desired amp hour for your MPPT, which is the maximum battery charge current. (Take a look at the example below)
Solar charge controllers are also categorized by another number which is the maximum solar panel system voltage.
What is the maximum solar panel system voltage?
Solar panels are connected in series or parallel or, in best cases, a hybrid of parallel and series to meet all voltage and amperage requirements of Inverters.
Clicking solar panels in series will add up the voltage of each panel and help with more effortless energy transfer by wires. And connecting panels in parallel will increase amperage and allow other solar panels to keep functioning even if one malfunction. Therefore a pack of 5 solar panels with an open-circuit voltage of 23 connected in series has a maximum voltage of 115.
We know the maximum Amperage of the system is 41.6 amps, and the maximum voltage is 115 volts. We recommend multiplying the number by 1.25 to protect all equipment from possible increases or surges of energy for safety. So the amperage that we consider should be close to 52amps amps and the voltage around 143V.
Looking at available solar charge controllers, we can see that the exact numbers are usually unlikely to exist. Hence, we look at available ones that differ least from our nominal values.
In this case, the Smart Solar MPPT 150/60 has a high enough maximum voltage and can support solar panels' current.
How to monitor the Solar Charge Controller?
Almost all controllers come with USB ports that allow you to connect to them by a laptop.
Some Charge controllers, such as Victron Energy Smart Solar, come with a built-in Bluetooth module. And you can use the Victron connect mobile app to connect to them directly or for remote monitoring.
In addition, some charge controllers are equipped with LCD screens that allow you to monitor the performance on site.
Our Recommendation for Best Solar Charge Controllers
Over the past few years, we have had numerous installations with different brands needing a charge controller, from our installations in Kanwata Outfitter to our newest innovation, the Li-Cube. The Victron Energy Smart Solar MPPTs are among the best charge controllers with outstanding efficiency and easy installation and programming.
The MPPT charge controller can be installed with all battery banks, such as Lithium or Lead-acid Batteries, to increase system efficiency like never before.
The Smart Solar 250V/100Amps comes with built-in Bluetooth and an option to add Victron Display for easier monitoring.
The Victron SmartSolar Charge Controller has an ultra-fast Maximum power point tracking (MPPT) controller that improves the energy harvest by 30% compared to PWM controllers and by up to 10% compared to the slower MPPT controllers. Especially in the clouded sky when the light intensity is changing continuously.