What is a charge regulator

What is a charge regulator?

The charge regulator is an electronic device whose function is to control the state of charge of the batteries to guarantee that an optimal filling is carried out and thus extend their useful life.

The solar charge regulator is installed between the photovoltaic field and the batteries and is responsible for controlling the flow of energy that circulates between the two elements. This control of the energy transit is produced thanks to the control of the parameters of intensity (I) and voltage (v) throughout the time that each stage of charge lasts.

We remind you that batteries require several charging stages that vary in voltage and intensity parameters depending on the model used . You can read the blog about the stages of charging a battery .

Characteristics of charge regulators

– The regulator is configured for the battery that is connected and will apply the appropriate algorithm that will maximize the useful life of the accumulator.

– It also protects the battery against possible overloads and excessive voltages, compensating for a higher voltage from the photovoltaic field so that the battery is not damaged depending on the state of charge in which it is at any given time.

– Depending on the manufacturer, the regulators can be complemented with external screens, communication devices, or it is integrated into the inverter itself if it is of the 3-in-1 type.

Types of charge regulators

The charge regulator directs and controls the amount of energy that flows between the battery and the solar panels. There are two types: the PWM charge controller and the MPPT.

PWM load regulator

It performs a pulse modulation and only works to cut off the energy flow between the panels and the batteries when they have been fully charged. For its correct operation, it must have the same nominal voltage in the solar panels and in the batteries , that is, if we have a 12V battery, we can only charge it with a 12V panel. The solar panel is made to work at the voltage of the battery in that charging stage, a working point that does not coincide with the maximum intensity that the panel can provide, therefore they do not take advantage of all the solar production and are cheaper .

If we need more charging power we can connect more 12V panels but in parallel so as not to add voltage.

With the PWM charge regulator, the modules work at the voltage that the battery is charged , which translates into energy losses. As soon as the battery reaches the indicated voltage, it begins to prevent contact between the modules and the battery to avoid overcharging -what is called the absorption phase-, but this leads to a decrease in energy efficiency, which represents a great obstacle. Its  advantages  lie in its price and ease of transport due to its low weight.

MPPT charge controller

Also called maximizers, since  their operation takes advantage of the maximum production of the solar panel to charge the battery . In addition to cutting off the flow of current to the battery when it is charged, this type of regulator receives the maximum production from the panel, making it work at its maximum point. It internally adjusts that voltage, which is always higher than that required by the battery, to the necessary voltage with great efficiency in the conversion, gaining intensity while conserving the total power of production. It is the best option to get the most out of solar panels and its extra cost more than compensates for its superior production capacity. Although they can work with panels and batteries in the same nominal voltage, its operation is more efficient if we increase the voltage of the photovoltaic field .

The difference with respect to the PWM is that  the MPPT regulator includes a maximum power point controller  (Maximum Power Point Tracking, hence its acronym) and a DC-DC transformer (which converts the high voltage direct current to higher voltage direct current). low voltage at the time of battery charging). This regulator  works with the modules at the voltage that is most suitable  at the time in order to extract maximum power or limit it in phases of absorption or float (phase in which the regulator has to keep the battery charged and prevents overloads and discharges).

That is why the MPPT regulator is more useful, since more photovoltaic modules are attached to it than they can to the PWM due to voltage incompatibility and these yield more. However, if we are going to work with a low power photovoltaic field, we can also use the PWM charge regulator.



How to choose the charge regulator?

A PWM regulator offers several figures : working voltage (12, 24, 48) and intensity (10, 20, 30… amps). We can only charge a 12V system with panels of that voltage, and we must never exceed the intensity produced by the panels that we connect in parallel with the nominal power indicated by the regulator.

An MPPT regulator offers 3 figures : working voltage in batteries, maximum working voltage in panels and load intensity towards batteries. We must not exceed under any conditions the working voltage in panels , which will allow us to organize its connection in such a way that it is always higher than the battery voltage and looking at the VOC figure in the data sheet of the panel. On the other hand, the intensity of charge to batteries will indicate the total power in panels that the regulator can manage, if it is 200W at 12V, it will be 400W at 24V. The installed power figure can be exceeded, limiting the regulator to the maximum power that it is capable of charging.

Finally, we must bear in mind that there are panels that will only charge the batteries correctly if we use an MPPT regulator and connect them in pairs or trios, since under certain conditions they will not produce enough voltage to fully charge the battery, damaging it prematurely.

Our recommendation is to follow the manufacturer’s instructions and consult us if you have any questions, since many of the breakdowns in solar systems are caused by a poor connection between the panels and the charge regulator.


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