PWM Charge Regulators – Buying Guide

Buy PWM solar regulators at the best price at; Charge regulators of all types, both PWM and MPPT charge regulators . For voltages of 12 and 24 volts, necessary to control the charge and discharge of a battery or accumulator within a solar installation. PWM solar regulators are installed between the solar panels and the battery to control its state of charge.


12V Charge Regulators

24V Charge Regulators

48V Charge Regulators


PWM Charge Regulators

Information about PWM charge controllers

PWM Charge Regulators for 12V, 24V and 48V: A large part of the charge regulators sold at AutoSolar are voltage regulators, this means that they are suitable for both 12V, 24V or 48V installations, regardless of the voltage that we are using in our photovoltaic solar installation. No type of voltage selection will be necessary prior to the installation of this type of solar regulator, the same solar regulator will read the battery voltage and make the adjustment , thus having a solar charge regulator that automatically adapts to the voltage.

How does a PWM solar controller work?

Unlike MPPT regulators , which work at the point of maximum efficiency of photovoltaic production, PWM regulators limit the production of solar panels in amperage , in this way the system does not always work at its maximum efficiency point. The regulator obtains a constant power and may not take advantage of the maximum photovoltaic production of the installed solar modules at all times. In other words, the PWM solar regulator reduces the input power of the solar panels to the batteries so that the voltage between both parts is equal and compatible , and will limit the intensity of the photovoltaic installation in the amperage of the regulator.

Calculation of the PWM solar regulator

PWM regulators should only be used in photovoltaic systems where the voltage of the panels and that of the batteries are similar , that is, for panels called 12V , which currently the most used would be of powers close to 150W-200W, we should work with 12V batteries . On the other hand, to work with 24V batteries , we should work with panels called 24V whose most used powers are currently around 3330W.

Therefore, once we connect the battery to the regulator , it will recognize its voltage (12V or 24V), and depending on that voltage, it will need us to connect a 12V solar panel for 12V batteries , and a 24V solar panel for 24V batteries . V.For solar panels connected to the grid or with 60 cells , we will need an MPPT controller .

The calculation of the PWM solar regulator is very simple, we just have to choose a regulator whose maximum amperage is higher than that of the set of installed panels . Adding the currents of the panels connected in parallel we will obtain the total amperage of the photovoltaic, with this data, and oversizing that current by 10% we will have the current necessary for the PWM solar regulator, which will have to be greater than that of the photovoltaic generator .

For example:

1 solar panel 12V with Im=8A, the reg. PWM needed would be 10A.

2 solar panels 24V with Im=8A, we will select a reg. 20A PWM.

It is important to note that the charging current must never exceed the value of the PWM solar regulator , since doing so will damage the regulator.

Solar panels should never be connected before connecting the batteries . If the charge regulator cannot deliver the current it gets from the solar panels , the radiator will not be able to dissipate all the excess current as heat, and the regulator will burn out .

Can I install a PWM in my photovoltaic installation?

In PWM-type regulators, the voltage value of the work field is the same as the voltage at which the batteries work.

When a PWM solar regulator is installed in a photovoltaic system, it is important to take into account:

– The panels compatible with the PWM regulators are the 12V and 36 cell solar panels or the 24V and 72 cells .

– PWM regulators have a maximum load intensity , if we exceed this value the regulator will burn. Therefore, we must carefully select the regulator to use, always leaving a margin that always gives us some flexibility in the face of low or high working temperatures.

– The working voltage of the photovoltaic field must always be at least 2V higher than the working voltage of the batteries , otherwise the charges will not be fully carried out. Therefore, the optimum values ​​should be greater than 14.4V for 12V installations and 28.8V for 24V installations.

– When making the connections, we must always connect the batteries first and the solar panels last . When disconnecting, the process will be carried out in reverse, opening panel fuses if we have them or failing that, disconnection of the regulator terminals and subsequently disconnection of the batteries.

– PWM-type regulators usually have working voltages of 12V/24V indistinctly, 48V models, on the contrary, in most cases are specific for that working voltage.

How should a solar panel be connected to a PWM charge controller?

As the acronym of its name indicates, charge regulators work by modulating the amplitude of the electrical pulse. They only control the battery charge voltage by making the solar panel work at the voltage at which the battery is at any given time. This presents us with the following conditions:

12V battery : With a PWM solar regulator we can only use 12V solar panels (they have 36 cells). And if we have to connect more than 1 panel , it will always have to be done in parallel (we will not be able to raise the working voltage) for which we can use a 2-pole distributor and make the job easier.

24V battery : With a PWM solar regulator we must put either a 24V solar panel (it has 72 cells) or 2 12V panels in series to reach the necessary working voltage. If we have to add more solar power, we must use 24V solar panels all connected in parallel. The simplest and most flexible is to use a 2-pole distributor . If we use 12V solar panels , we must make connections in series-parallel pairs and we will always need an even number of solar panels .

48V battery : With a PWM solar regulator we must put at least 2 24V panels in series (72 cells) to reach sufficient working voltage. If we have to add more solar power, we will have to make connections in series-parallel pairs to respect the 48V voltage, so in the end we will need an even number of solar panels . As in the previous cases, with a 2-pole distributor we can easily make all the parallel groups.

As a warning about PWM regulators :

-We should not use 60-cell panels as they deliver too much current for 12V systems and too little for 24V systems. Its use is restricted only to MPPT regulators or network connection.

-Never exceed the maximum charge current of the regulator. The current intensity in Amperes of panel production should never be higher than the figure marked by the PWM solar regulator model.

Most common uses for PWM solar regulators

The most common uses of PWM regulators are:

– In installations with low energy demand where the solar panel is 12V and the battery bank is 12V .

– It is very useful in installations where the solar panel is 24V and the storage system is 24V , in this way we reduce the cost of the regulator, since the cost of the PWM solar regulator compared to the MPPT regulator is cheaper.

– It is very popular in low budget installations .

How to choose a PWM solar regulator

We will have to take into account, above all, the intensity of the panels in our installation and their respective 12V or 24V voltages . The charging current will be the sum of the currents of each panel placed in parallel.


For a 12V installation.

– 12v batteries and panels .

– If we place 1 panel for example of 4.8A, the PWM solar regulator must be greater than 4.8A.

– If we place 2 panels with 4.8A, the PWM solar regulator must be greater than 2X4.8A.

Advantages of using a PWM solar controller

There are many advantages of using a PWM charge regulator complemented by a solar installation, independent of the electrical current. A PWM solar regulator increases the charging power in the batteries , thus allowing rapid recharging and effective maintenance of the life of these batteries .

We can highlight the following characteristics in these regulators :

Loss of battery efficiency : Batteries tend to age over the years. The PWM regulators are adjusted to the batteries , therefore, the regulators allow to end the problems associated with the charge and discharge that these devices suffer.

We avoid problems of excessive heating in the batteries and help to reduce gases : these PWM-type regulators have a faster charging power than other regulators , in this way we avoid problems of overheating and expulsion of gases that can affect the battery .

Increase in charge acceptance : the term charge acceptance is a fundamental element in solar batteries , it has had an impact on photovoltaic panels . PWM regulators are an advantage with this, since it allows to increase the charging capacity of the batteries , thus allowing the panels to generate more energy and this can be captured.

Equalizer between PWM regulators : A large number of PWM solar regulators more optimally support the battery cells through equalization, thus guaranteeing better loads and avoiding damage to the battery power.

Maintaining the best performance in the batteries : preserving the battery life as best as possible is essential, for this reason it is essential that the charge must be kept high, since our purpose is to preserve an optimal installation and maintain its operation. The figures of the regulators show greater profitability of the batteries , whose justification is the series of charge and discharge.

Recover battery discharge : the progressive loss of performance of lead batteries in solar installation constructions is a serious problem. Not charging enough leads to grid corrosion and sulfate crystals on the positive plate part above the battery . Studies regarding PWM regulators have shown that they are renewed over time, manage to recover the lost capacity charge, and at the same time, favor by avoiding the inlay of sulfate in the tank.

Self- regulate if a drop in voltage or temperature is perceived : just as the old charge regulators were sensitive to changes in temperature or voltage drops, they came to cause problems for battery charges . The same thing no longer happens with PWM regulators , since they reduce the power to lessen these consequences.

When analyzing this type of regulators , there are certain advantages and disadvantages. Among the advantages, it sounds very attractive to be installed as an alternative to supplying yourself with solar charging, but it should be borne in mind that these regulators have sharp pulses that the PWM solar regulator needs, and these can cause interference between devices such as televisions or radios, if these are close to each other. Another disadvantage to highlight is that they greatly limit the development of the system.

What functions should a solar regulator have?

There are several types of batteries that exist; open lead acid batteries , AGM batteries , GEL batteries , lithium battery … depending on the battery model we decide on, we have to bear in mind that each one has different charging powers, and it is an important element to take into account to avoid do damage to the battery . In other words, the solar regulator has to adapt to the battery that we are going to implement. In general, these PWM solar regulators have a standard setting type for batteries ,AGM batteries , open lead acid batteries and GEL batteries .

We would have to take into account if the selected battery does not have a standard charge setting. In this situation, we would need the solar regulator to be programmable by the buyer, since we would need to program the voltages that the manufacturer recommends for its correct use.


It is advisable that the regulator is in charge of reporting the progress of the charge that the solar panels are acquiring , of the voltage that the battery has and in the event of an incident, that it inform us. There is a type of regulator called digital display that is responsible for informing of these previous elements on a screen that is incorporated, this allows us to consult the information in a brief and simple way, and will help us to know at all times what state it is in. our solar mount.

Solar regulators that do not have a digital display have built-in LED lights which inform the state of the battery and indicate in case of an incident, with different colors to differentiate the cases. Although neither the battery voltage nor the load capacity of the panels can be consulted .

Maximum allowable charging current

The solar regulators have incorporated in the instructions the recommendations of the maximum load power allowed.

From our experience, we advise not to get rid of the informative manual of the solar regulator , also for any incident you can also consult the solar installation instructions.


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