Classification of solar panels by voltage
The solar panels can be classified in many ways. We can classify them according to whether they are monocrystalline or polycrystalline, also according to their cell technology, whether PERC, PERV, etc., by their power or current intensity. Among all these classifications, one of the most common is to classify them according to their voltage, whether they are 12V, 24V, 48V or very rarely, 96V panels.
What do the voltages 12V, 24V and 48V mean in a solar panel?
These values are classification groups that have been established informally in the photovoltaic industry, but do not represent an actual value of the solar module.
Solar panels classified as 12V are those that have a maximum power voltage between 15V and 19V. On the other hand, 24V panels have a maximum power voltage between 36V and 39V. The 48V and 96V photovoltaic modules have maximum power voltages that are close to these values, although their use is less frequent.
Typically, 36-cell panels will be those in the 15V to 19V range so they will be considered 12V. Whereas 72-cell panels will be 24V as they range between 36V and 39V.
When reading the technical specifications of the solar panel, we can discern which classification the panel would fall into by looking at the Maximum Power Voltage (Vmpp) value.
Why are solar panels classified as 12V, 24V and 48V?
The relationship of these voltages is with the solar batteriessince they are divided into those with a voltage of 12V and 24V.
In order for solar panels to charge photovoltaic batteries they must produce energy at a higher voltage than the battery voltage. Therefore, a so-called 12-volt panel, which produces energy at a voltage between 15 and 19 volts, will be able to charge a 12-volt battery but not a 24-volt battery. In addition, manufacturers expect that the conditions in which the panel is located can produce a voltage drop. A panel with a voltage of 15V may see its voltage reduced to 13V due to, for example, cold weather. But it will still be sufficient to charge the battery properly.
Can 12V batteries be charged with 24V solar panels?
A 24V module can charge a 12V battery thanks to a MPPT regulator that, regardless of the input voltage being higher, will regulate it to the indicated value by performing a DC/DC conversion avoiding power loss due to the voltage difference.
Can 24V batteries be charged with 12V solar panels?
A 12V module cannot charge a 24V battery. Even if we use a solar regulator as in the previous case, it is not able to increase the voltage of the energy it receives, so at the output, the energy would not have the necessary voltage to charge the battery, since it needs to be higher than 24V.