What Is the Maximum System Voltage in a Solar Panel?

Solar panels are becoming increasingly popular as alternative and renewable sources of energy for the home. But what does maximum system voltage in solar panels mean? And why does it matter?

The terminology can seem daunting to a new user of solar energy. But as always, we aim to make understanding solar energy and its terminology simple. So read our guide below to get a better grasp on the issue of maximum voltage in solar panels. 

We make it easy for you to calculate the maximum system voltage of your solar panel array, even if you are new to solar energy.

Solar Panels’ Maximum System Voltage - What Does It Mean? 

Maximum system voltage is the maximum voltage at which your solar system array should be operated. This metric is crucial when you connect an inverter or controller to your array. So, why is this important, and how do we calculate it? 

We get it - solar system terminology can be confusing. Most residential solar installations are a 12 v solar system. And you may know that in a 12v vs 24v solar system, their appearance is similar but the 24v system has twice the number of solar cells. 

To those without a background in electronics, terms like 200 amp solar system, or 1,000w solar system may just confuse you. That is why we aim to break down the jargon into simple language everyone can understand. 

So, your solar panels should have the maximum system voltage that your solar inverter or controller that they are connected to, can handle. Let’s examine this a bit closer.

Why Is Maximum System Voltage Important?

If the voltage supplied by your solar panel array is too high, it won’t work and can cause damage to your system. This is because the inverter will fail or shut down when the maximum system voltage exceeds the inverter’s capability.

Is It Possible To Calculate It At Home?

Exceeding the maximum system voltage can lead to equipment failure. You can calculate the maximum system voltage of your solar panels at home, and it’s not as difficult as you think. Just follow our step-by-step calculator below.

How Is Maximum System Voltage Calculated?

Maximum system voltage is calculated by taking some basic information and following our instructions in 5 easy steps. Let’s examine the information you will need before you do your calculation, and how to find them.

Standard Test Conditions (STC) of Your Solar Panels

This is the term used by solar panel manufacturers when testing and rating their solar panels. This should be indicated on the packaging of your solar system panels, or easily available from the manufacturer’s database.

Record-low Temperature for Your Region 

This is the minimum temperature that may be experienced at your location. Check out your local weather statistics for this temperature. 

There are several weather statistics services available online, but this online weather statistic resource is one example of what you can use.

Temperature Coefficient of VoC 

The temperature coefficient of VOC (open circuit voltage) determines performance relative to temperature. VOC is the voltage the solar panel will generate without an inverter, charge controller, or solar batteries.

The voltage that your solar panels work at depends on the temperature of the cells inside. The higher this temperature, the lower the voltage your solar panel will produce. 

The reverse is also true. The lower the cell temperature, the higher the voltage the panels will produce. 

This information is indicated on the panel’s datasheet.

Inverter’s Maximum Input Voltage

Your solar panel inverter converts the direct current of your panels to an alternating current.

If you add more solar panels in series the voltage of your solar array will increase. Your solar panel array must be connected to suit the inverter's maximum input requirements.

The inverter has a maximum input current, for example, 40A for 40kW. Only when the input voltage exceeds 550V, will the output be likely to reach 40kW. 

The maximum input voltage will be found on the datasheet of your solar inverter.

Foolproof Step-By-Step Maximum System Voltage Calculator

Once you have obtained the information described above, follow these 5 steps in order. 

Step 1

The STC temperature the manufacturer used will probably be room temperature, about 25 degrees Celsius/ 77 degrees Fahrenheit. 

Wherever the STC figure is, the record-low temperature for your location must be deducted from that. Once you have an answer, proceed with step 2.

Step 2

The result from step 1 must be multiplied by the temperature coefficient of VOC. The resulting figure is then further multiplied by the module VOC found on the panel’s datasheet. 

The resulting answer tells you how many volts each module will increase during record-low temperatures. 

Step 3

Add that final figure from the calculations in step 2 to the module VOC to get the VMax figure. You will need this for step 4. 

Step 4

Divide the inverter's maximum input voltage by that VMax figure obtained in step 3, and round the result down to a whole number. 

This gives you the maximum amount of modules that can be wired in a series string for your inverter and location. It’s important to know how many solar panels you should wire in series.

When solar panels are wired in series strings (with the positive terminal of one panel connected to the negative of the next panel), the voltage of all panels is added together to get the total string voltage. 

Step 5

Multiply this amount of modules by the VMax and you’ll have your maximum system voltage. This is the voltage that your solar inverter will need to handle. It will allow you to match the right inverter to your solar system.

Conclusion

With the right information and our easy-to-follow maximum system voltage calculator, anyone can match the right inverter or controller to their solar system. 

Do you need further assistance with installing solar panels in your home, or with finding the right inverter for your solar panel array? Get in touch with us today.

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