What is an MPPT controller
A charge regulator, or charger inverter, is a device that is installed between the solar panels of an isolated installation —be it that of a home without access to the general electrical network, as well as that of an agricultural plantation, the lighting of a garden…—and the battery, which stores electricity. These are used for regulate the amount of energy that passes to the battery through the solar panel in order to prevent it from overloading once it is complete and, consequently, ending up breaking down. We must bear in mind that the maximum charge capacity of the batteries is 14 volts.
At that point, the solar charge controller will stop the battery from charging any further, so it automatically shuts off, leaving the solar panels and battery isolated and discharging any excess power. The charge regulators work by adapting the variation of potential, or volts, between the solar panels and the battery, until the battery voltage reaches 14 volts —or what is the same, its full charge—.
Related: PWM, MPPT and the efficiency of the photovoltaic system
What is an MPPT controller?
An MPPT regulator is a charge controller that is used to regulate the amount of electrical power that is supplied to a battery. In this type of charge regulator, what is achieved is extend the voltage of the solar panel and make the most of its power. They use all the energy that the solar panels can supply by constantly monitoring the battery voltage.
How does an MPPT charge controller work?
The regulator always works with the voltage at maximum power of the panel —not counting the one that can always be lost until reaching the battery, since it is not an open circuit—. The MPPT regulator uses the difference between the maximum voltage of the panel and that of the battery —at 14 volts— during the entire battery charging process. For this reason, the MPPT charge controller always draws its maximum power from the panel and use more energywithout stressing the batteries that do not reach, for example, their minimum charging voltage of 24 volts in a poorly made solar installation.
When to use an MPPT solar charge controller?
The most advisable thing is to use an MPPT solar regulator when the solar installation has 24V panels and 60 cells. That is, those known as network panels. In this way, what will be achieved with an MPPT regulator is to solve the problem of panels that do not reach the optimum battery charging voltage, amplifying it and converting it into a panel similar to that of 72-cell plates —insulated panels—.
Difference between PWM and MPPT regulator
The main difference between PWM and MPPT regulator is that in the PWM regulator the panel provides the power (Watts) in function of battery voltage. The less load and less battery voltage, the more power. Now, as the voltage (volts) rises, the current supplied is less —that is, the energy absorbed per unit of time is less—. If the battery is fully charged, there would be a loss of power here as the panel would continue to produce more power. On the contrary, in MPPT panels, they use 100% of the energy provided by the panels since they work with the maximum power voltage of the panels, constantly controlling the voltage or voltage of the batteries. The use of one regulator over another depends on the use we want to make of the energy, as well as the amount of voltage at maximum power with which they work and the solar panels or cells of the solar panels that the solar installation has.
The MPPT inverter/charger/regulator is more expensive than the PWM, but it makes better use of the energy and amplifies it. In the event that we have a traditional installation with panels of up to 72 cells, for example, these usually offer a maximum voltage of 37 volts. For this reason, using an MPPT regulator is not so practical since the investment would be expensive. Now, if we find ourselves in a situation in which our installation does not provide enough energy to compensate for the minimum charge that the battery needs, then it will be advisable to use one of these or expand the number of cells in the solar installation.
What solar panel do I have and what charge regulator do I need?
In general, we can find two types of solar panels or panels. These are the network panels and isolated panels. Network panels are usually those that are directly connected to the electrical network and the energy is never lost since, in case of overload, it is poured into the network. They are the panels that are commonly used in buildings within the city or in urbanizations not far from large cities. Also in the case of complexes or industrial estates. These panels typically provide a peak voltage of 29V. Isolated solar panels are those that are used in isolated homes in which the general electrical network does not reach. These usually have a voltage at its maximum point of 37V. To find out what type of plate you have, the process is very simple. You only have to look at the label that is stuck on the back and in which it is specified if it has a total of 72 cells, which would be an isolated plate, or 60 cells, which would correspond to a network plate. If you cannot locate the stickers, you can also choose to count the photovoltaic cells that your plate or solar panel has. It is very important that you take this information into account when buying your MPPT or PWM regulator to prevent the battery from being damaged, as this is usually one of the most expensive parts that make up the entire solar electrical installation.
