# Determining Voltage & Current

Posted on 01/26/2018 at 12:00 AM by Daniel Stieler, Phd

How can you determine voltage and current of a solar module? This is a pretty common question so let's dive right in.

The voltage of a solar module is based on the number of cells in a module.

Each different solar technology has a characteristic voltage per cell based on the physical properties of the materials that the cell is composed of.

There are two voltages that are important for a solar modules. The open circuit voltage (Voc) is the maximum voltage that the cell will produce and it occurs when there is no current supplied by the module.

The power point voltage (Vpp) is the voltage at which the maximum power is available from the cell. The voltage of a module is simply the characteristic voltage of a cell multiplied by the number of cells.

The current a solar module will produce is based on the area of the smallest cell.

Since the current in an electrical circuit is the same throughout any series string in the circuit, the current out of a series connected solar module is the current generated by the smallest area cell.

Each solar technology will have a characteristic amount of current it can generate per unit area. Knowing that value and the area of a cell will allow you to calculate the current output of a cell. Much like voltage, there are two important values for current.

The first is the short circuit current (Isc). Isc is the maximum amount of current a module can supply and it occurs when the module is shorted and there is no voltage produced by the solar.

The second important current is the power point current (Ipp). This occurs at the point on the curve where Vpp occurs and is the point of maximum power production for a module.

What seems like a basic almost rudimentary question can actually be quite important when it comes to how to design your systems.

When you want to power your unique product determining what solar material is best, what technology you should use and who you should partner with are crucial questions.

Categories: Solar Education