Installing solar panels requires understanding how many components work: solar cells, inverter wiring, pipe bending... If you do it yourself, you can almost work like an electrician once the installation is complete!
Charge controllers are an integral part of solar power systems that confuse many people. A solar charge controller is required for most residential photovoltaic panel installations. Let's explore what a solar charge controller actually does and whether you need one to install.
What Is a Solar Charge Controller?
A solar charge controller is a device that regulates the energy that enters the battery from the solar panel. Solar generators convert electrical energy and store it in batteries that are charged by solar panels. The solar charge controller regulates the current to protect the battery from surge damage and shorten its service life.
If your photovoltaic solar array powers the battery pack, a solar charge controller is essential. If you are using a grid-connected system, you may not need a solar charge controller.
How Does a Solar Charge Controller Work?
The solar charge controller regulates the voltage transmitted from the solar panel to the battery.
Solar panels for 12V battery systems are typically rated at 17V. This may seem counterintuitive, but there's a good reason for it.
Solar panels rarely output their full rated power due to clouds, dirt on the panels, or other environmental factors. So, if their rated voltage is only 12V, they will output less power - which is unacceptable for 12V batteries.
A stationary 12V battery is about 12.7V, and a rechargeable battery is about 13.6 to 14.4V. So, solar panels must produce at least that much power output.
The solar charge controller takes 16 to 20 volts of electricity from the solar panel and lowers it to the current voltage required by the battery. Depending on the battery's current, temperature, and the controller's charging mode, this power can range from 10.5V to 14.6V.
The charge controller ultimately prevents battery damage. Inconsistent power output, power surges, and other external factors can overcharge and damage solar cells.
Type of solar charger controller
There are two main types of charge controllers :PWM and MPPT. Neither is necessarily "better" than the other - each has its own advantages depending on climate, array size, and system components.
While MPPT controllers typically cost more than PWM, the difference is negligible when considering the total cost of a solar installation. Always choose a controller because it is the right tool for the job, not because it is cheaper.
PWM Charge Controller - PWM(pulse width modulation) controllers are generally smaller and less expensive than MPPT controllers. PWM controllers are often standard on small solar systems, such as RV and small cabin setups.
When using a PWM controller, the voltage from the array needs to match the battery voltage. When using PWM controllers, off-grid solar panels (rated at 17-18V) are required, which sometimes costs more than grid-connected solar panels (typically rated at 37V).
PWM controllers work best in "ideal" conditions - warm, sunny weather. When the weather gets cold, the efficiency of the battery is reduced.
The PWM controller cannot regulate the voltage. Instead, it switches as the voltage of the solar array inevitably changes, and this automatic shutdown also causes some power loss.
MPPT Charge Controller - MPPT(Maximum Power Point Tracking) controllers are more expensive than PWM, but in many cases more efficient.
MPPTs outputs current at a rate based on the maximum panel voltage. They can use high-voltage arrays and low-voltage batteries. You can use the mass-produced low-cost PV module standard in your home.
The MPPT controller can accept and modulate different voltages. They utilize excess power that would otherwise be wasted by PWM.
Who needs a solar charging controller?
All off-grid solar systems require a solar charge controller to regulate the energy going in and out of the battery.
For grid-connected renewable energy systems, solar charging controllers are usually not required. The utility collects the excess energy generated and uses the electricity.
When should I use a solar charge controller?
Almost all solar systems that utilize batteries require a solar charge controller. Small solar installations are the only exception - 5-watt trickle chargers and similar devices are not required.
For example, many golf cart owners use a small panel to charge their batteries in the winter. This setup does not require a charge controller between the panel and the golf cart battery.
If you are connecting a 400W panel array, you will need an adequate solar charge controller (probably of the MPPT variety).
Some solar solutions already have charge controllers built in, such as the EcoFlow portable power station. Controllers, batteries, inverters, power outlets and everything else are part of a power station - you just need to add solar panels.
How to adjust the charge controller correctly?
Solar charge controllers come in a variety of sizes for arrays of different voltages and currents. Choosing the wrong one can lead to power loss and inefficiency.
First, you need to check the rated voltage on the charge controller. Most PWM controllers are rated at 12 or 24V, while MPPT controllers can handle 12, 24, 36, and 48V systems. Powerful off-grid energy solutions such as EcoFlow's power kit with MPPT charging controller and built-in 48V battery.
Most charge controllers have an "amperage" rating. Smaller PWM controllers may be rated at 10, 20, or 30 amps. MPPT controllers are typically rated at higher amps - 80 or 100 amps are common - to accommodate larger PV arrays.
To determine the potential number of amperes that a solar array can output, we need to do a simple calculation:
Ampere = Watt/volt
Suppose you have an 800-watt array operating at 12 volts. We can plug these numbers into the equation:
Amps = 800 watts / 12 volts = 66.67 amps
The system can produce a current of up to 66.67 amps. A charge controller below this value may overload and fail. For this example, you need a charge controller rated at 70 amps.
You also need to check that the battery is compatible with the charge controller. Lithium-ion batteries and lead-acid batteries use different technologies. Most controllers are designed for one type of battery or another.