Solar Panel Voltage Output Explained

How much voltage can a solar panel produce?

This question gets asked a lot, so let’s help clear things up.

The solar panel output voltage depends on the efficiency of the solar cell used, the number of solar cells in series, the intensity and the angle of the sunlight received, and the temperature.

But before getting into what is the average solar panel voltage output, first, you must know that there are 3 types of voltages in photovoltaic (solar electric) systems:

1. Open Circuit Voltage (VOC)
2. Maximum Power Voltage (VMP or VPM)
3. Nominal Voltage

Each one of them is measured under different conditions and has a different purpose.

And in this article, you will discover each one’s definition, what factors affect it, and how much voltage can solar panels produce.

After reading this article, you will know everything there is to know about solar panel output voltage, so let’s get started!

Key Takeaways

• Solar panels’ open circuit voltage (VOC) is between 21.7V and 43.2V depending on the number of solar cells in series.
• Solar panels’ maximum power voltage (VMP) is between 18V and 36V depending on the number of solar cells in series.
• Solar panels have a nominal voltage of 12V, 18V, 20V, or 24V.

Types of Solar Panel Output Voltages

1. Open Circuit Voltage (VOC)

Open circuit voltage is the maximum voltage that a solar panel can produce and it occurs when there is no external load connected to the solar cell, so all the generated electricity is used to overcome the cell’s internal resistance.

In simple terms, it’s measured when the solar panel is not connected to any devices or appliances.

The open circuit voltage has 3 uses:

First, it’s used to measure a solar panel’s maximum power output potential.

Secondly, it can be used as a reference voltage for the Maximum Power Point Tracking (MPPT) algorithms in solar charge controllers.

Finally, it can be used to calculate the temperature-corrected VOC.

How Much Open Circuit Voltage (VOC) Does a Solar Panel Produce?

2. Maximum Power Voltage (VMP)

The maximum power voltage (VMP) is the voltage when the solar panel is connected to a load and is operating at its maximum power output under Standard Test Conditions (STC).

In short, it’s the point where the solar panel produces the most watts and it’s usually 70%-80% lower than the open circuit voltage (VOC).

How Much Maximum Power Voltage (VMP) Does a Solar Panel Produce?

3. Nominal Voltage

The nominal voltage is not a real voltage that can be measured, it’s simply an approximate voltage to help you match equipment.

This voltage is based on the nominal voltages of the devices that are often connected to the solar panel, such as charge controllers, inverters, batteries, other solar panels, and loads.

For example, if you need a solar panel to charge your 12V battery, you can simply buy a 12V solar panel and it will work perfectly fine.

While the nominal voltage can be different than the actual operating voltage, it will still be in the same ballpark.

For example, a 12V battery can have an operating voltage of 11.5V or 14V, but it will still be called a 12V battery.

The same goes for solar panels, the actual operating voltage of a 12V solar panel might be 13V, 17V, or even 23V, all these volts will still be in the operating range of a 12V solar panel and will charge your 12V battery just fine.

In short, the nominal voltage is simply used as an approximate voltage to help you match equipment more conveniently.

What Is the Nominal Voltage of Most Solar Panels?

The most common solar panel nominal voltages are 12V and 24V solar panels.

What Affects Solar Panel Voltage Output?

1. Solar Cell Efficiency

The efficiency of the solar cell is defined as the ratio of the electrical power output of the cell to the incident light power.

The higher the solar cell efficiency, the more voltage the cell can produce from the same amount of sunlight.

2. Solar Cell Size

Bigger solar cells mean a bigger surface area.

This increases the number of photons that hit the cell, thus, it increases the voltage output per square foot.

3. Number of Solar Cells in the Panel and How They Are Connected

Solar panels can have anywhere from 36 to 72 solar cells connected together.

But what really affects the solar panel voltage output is how they are connected together.

In solar systems, solar cells are connected together in series or in parallel.

When you connect solar cells in series, the voltage of the solar panel will increase.

But when you connect solar cells in parallel, the current of the solar panel will increase while the voltage stays the same.

So, if you want to increase the solar panel voltage output, you need to connect more cells in series.

4. Sunlight Intensity

The amount of sunlight that hits the solar panel also affects the solar panel voltage output.

More sunlight means more photons and more electricity produced.

5. Sunlight Angle

The angle of the sun’s rays affects the solar panel voltage output.

When the sun is at a low angle, the sunlight has to travel through more atmosphere, which means that some of the photons are scattered and don’t make it to the solar panel.

This results in lower voltage output.

Solar panels work best when they are perpendicular to the sun’s rays, as this is where they receive the most direct sunlight.

6. Temperature

Solar work best when they are cool.

This is because the higher the temperature, the higher the resistance of the solar cell’s materials and the more electricity is lost as heat.

Solar panels have something called temperature coefficient which defines the percentage of solar power lost for every degree Celsius above 25°C (77°F).

So, if you want to increase the solar panel voltage output, you need to keep the solar panel cool.

Conclusion

The average 12V solar panel produces around 17 volts but keep in mind that this output voltage is affected by many factors, so it’s not always possible to get the exact voltage you want.

In the end, we really hope you enjoyed the article as much as we did.

If you have any questions about solar panels, please share them with us in the comments section below.