The best choice in solar panels: 12V or 24V panels?

There has always been a classification of the panels by their voltage because they were referring to the standard battery voltages, which are 12, 24, 48 or exceptionally 96 volts.

Take a look at this article and solve your doubts about the concept of “12V panels” or “24V panels”.

What really is a 12v panel?

These are some of the factors to consider;

• The working voltage of a panel depends on the temperature.
• The panel always has to reach a high enough voltage to be able to charge a 12v battery (which would really be 15v).
• If we have to reach 15v in any of the temperature conditions, the higher the temperature, the lower the voltage would be, so what is done is that a panel is designed in which the maximum power point (which, for example, we classify as a panel of 100w, etc.) produce it at about 17v because in the worst case we will drop to about 15v and we will have enough voltage to charge the battery.

How do you get those 17 v?

• Each cell puts out about 0.5 volts or so at the point of maximum power. If we divide 17 / 0.5 we get 36 cells.

So we can say that in general any module that has 36 cells in series could be considered what is known as a 12V module. The module would deliver a current at that voltage close to the Intensity at the Maximum Power point (Imp) on the label, charging the battery with a PWM or MPPT regulator with a power similar to its specification.

In the case of 24V, it would be double and instead of 36-cell panels we would be talking about 72-cell panels. If we want to charge a 12V battery with a 24V panel, an mppt regulator should be used since, although they are the panels that are designed to charge higher voltage batteries, the MPPT regulator performs a DC/DC conversion and we would not lose power. If a PWM regulator is used, it would also work, but half of the panel would be lost because at the moment in which we circuit to charge the battery, the panel would start working at voltages of 12, 13, 14 V, which would be as if we had a panel of only 36 cells.

We can also find 60-cell panels on the market , which we could not classify as 12V or 24V panels (36 or 72 cells). It is a type of panel that was really designed for network connection installations. It can be used with 12V batteries but it is also recommended to use mppt charge regulators because with a PWM regulator a third of the panel would also be wasted (it is a panel that gives more voltage than is needed, at the moment of connecting the battery what determines the voltage is that of the battery).

In short, when we talk about 12V or 24V solar panels we refer to the number of cells that the panel has, 36 cells for the 12V and 72 cells for the 24V.

We cannot deduce that working at 12V or 24V is a better or worse option and, therefore, it will depend on our installation, the consumption we have and the use we are going to give it. Normally working at a higher voltage always reduces electrical losses, but in small installations it adds unnecessary cost.