When we talk about a solar panel we can distinguish two types, mainly. These are the thermal solar panels —for water heating installations— and photovoltaic solar panels —the most used, to generate electricity using sunlight—. In any case, we must take into account the specifications of the product that we are going to buy since these will be better adapted to one installation or another. For example, in the case of photovoltaic solar panels for isolated installations, we will also need batteries —in which case we must opt for a panel with a higher voltage than these—, but also charge regulators and inverters.
Tips to understand the technical sheet of a solar panel
For this reason, it is essential to understand the data that appears reflected in the technical sheet of a solar panel to adapt it to the necessary conditions of the corresponding installation. Next, we explain how to understand the technical sheet of a solar panel and everything related to it, such as the fundamental concepts of the battery technical sheet for solar panel. Let’s start!
Technical sheet of a solar panel
The technical sheet of a solar panel is a label that appears stuck to the back of the solar panel with the corresponding safety certifications and warnings, as well as -of course- the specifications about its benefits that help us to know how to understand the technical sheet. of a solar panel. These data are the following:
- PMAX, Maximum Power: This is the main number that defines the model of the panel with which we find ourselves. This measurement determines the maximum power that the solar panel can supply, that is, the point of greatest intensity and voltage calculated under standard measurement conditions. The maximum power can also be obtained by multiplying the Voltage at Maximum Power —or VMP— by the Current at Maximum Power —or IMP—.
- VOC, Open Circuit Voltage: This voltage is measured in volts and corresponds to the number of volts it can supply when unplugged. That is, it is the maximum voltage of the solar panel without having any load connected. To measure it we need a voltmeter. Now, you should bear in mind that the values may vary depending on various factors, such as atmospheric conditions —whether it is cold or hot. This value is also reflected on some occasions as VCA.
- ISC, Short Circuit Current: The intensity in Short Circuit corresponds to the amount of current expressed in amps that the panel can generate in a short circuit situation. This is produced at a voltage of 0 volts, so it can be measured directly at the terminals through an ammeter. For this we can connect the positive cable of the panel with the negative and proceed to its measurement.
- VMP, Voltage at Maximum Power: This measure of the technical sheet of a solar panel has to do with the voltage that is produced at maximum power, of course, under standard measurement conditions. This figure helps us determine what type of panel we have. That is, if it is 12V or 24V, which are the most frequent. In case it is 12V, the VMP must be between 15 and 19V while, if it is 24V, the number of this measurement must range from 36 to 39V. These figures are measured as follows because the solar panel voltage must always exceed the battery charging voltage, which can be found in the battery for solar panel data sheet.
- Others: Other specifications that we can find in the technical sheet of a solar panel are the weight and dimensions, as well as the standard measurement conditions that were used to carry out the measurement of the values specified in the solar panel, such as the temperature. Let’s not forget, likewise, the contact details of the manufacturers, as well as the origin of the solar panel, among others.
Fundamental concepts of the technical sheet of the battery of a solar panel
We have just explained how to understand the technical sheet of a solar panel. It is also important that we take into account some fundamental concepts about the battery for solar panel data sheet, since these are usually the most expensive components of the installation and the ones that break down the fastest if we do not carry out an installation or maintenance. due to overcharging and electrolytes in some battery models that require maintenance. When we buy a battery for solar panel we must look at:
- The capacity: The battery capacity, or Nominal Capacity —CN—, corresponds to the duration of its discharge while it is working. The battery capacity value is provided by the manufacturers. In the technical sheet of the batteries for solar panels, it is indicated as C10, if the duration is 10 hours, and C100, if the duration is 100 hours. Let’s see an example: If we have a battery of C100 = 130Ah, this means that the battery can supply 13 Amps for 10 hours.
- discharge depth: In this case we find the value expressed as a percentage of the total battery capacity that is used during a charge or discharge cycle. In the case of surface discharges, the depth of discharge is usually 20%; while, in the case of deep discharges, the value usually ranges between 60 and 80% of the nominal capacity.
- The tension: The battery voltage is what determines the type of battery we are dealing with. This measurement serves to know how much energy is necessary for the electrical charges to circulate inside the circuit. In general, the battery is usually 12V, although we can also find 24V —for large installations—. 12V battery models usually have capacities of up to 300 or 400Ah.
Here are some tips for understanding the technical data sheet of a solar panel.