How to find voltage of a photovoltaic module or solar panel?

Solar Power is a hot topic nowadays, but information about its installation is not very common. From engineering point of view , one must know the open circuit voltages of panels in order to select a suitable charge controller for the system. Also the panel voltages will decide how many solar panels to be connected in series to achieve desirable voltage against the charge controller available. The Engineers is bringing a series of posts and videos regarding information about solar panel systems both for domestic use and commercial uses.


First let us look at an individual solar cell. One solar cell has a voltage of around 0.58 volt. Several cells are connected in series to form a solar module.

To design a photo voltaic module for a 12v system, 36 cells are connected in series. This causes open circuit voltage to be around 22 to 23 volts.
Why is there a gap between the open circuit voltage and the system voltage?

This is because the when load is applied , the voltage drops to a lower value. Also this margin will help the maximum power point tracker solar charge controller to
find and choose the maximum power point voltage and current values.

To design photo voltaic module for a 18 volt system , 54 cells are connected in series to produce a open circuit voltage of around 32 volts. Similarly , 20 Volt system
60 cells are connected in series .

54 cells and 60 cells panels are designed for specific systems which use super capacitor storage systems.

A 24 volt system would require a panel with 72 cells connected in series, and a 30 volt system would need a panel with 90 cells connected in series.

I hope after watching this video, you will be able to identify the open circuit panel voltages and the designated system voltages by looking at the cells on a photo voltaic module or simply, solar panel.


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