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Open Circuit Voltage for Solar Panels

If you are considering going solar in San Antonio, it’s important to do some research on which type of solar panels is best for your home. A great way of comparing solar panels is by looking at their specification sheets, or spec sheets. However, if you are new to solar energy, you may feel a bit overwhelmed by all the terms used. In this week’s article, we are going to explain one of the terms often thrown around: open-circuit voltage (VOC).

What is Open Circuit Voltage?

According to PVEducation.org, the term refers to the maximum voltage available from a solar cell and this occurs at zero current. Basically, it’s the most voltage a solar panel can produce without causing an electrical fire and/or power outage. The number helps the solar installer and electrician determine the amount of panels connected to a charge controller or inverter. For the sake of brevity, we’ll assume you’re a homeowner interested in a grid-tied solar panel system and only inverters need further discussion.

Inverters are used to convert the DC power from the solar panels to the AC power in your home. They work within a certain range of volts. If the voltage going through an inverter is too high or too low, you risk damaging the inverter thereby decreasing the lifespan of your system.

specifications of a mission solar panel
Specifications of a 300 W Mission Solar panel

The open circuit voltage value is always higher than the operating voltage because there’s no load or resistance when measured. You can measure your panel’s VOC by using a digital multimeter with leads. Connect the leads of the multimeter to the panel without any other electronic connected. The measurement on the multimeter should be close to the spec sheet’s VOC. However, keep in mind the spec sheet’s listed VOC is at standard testing conditions (a sunny day around 77 F). If you try measuring the open circuit voltage during the summer in San Antonio, the value will be a bit lower than the one listed because of the warmer climate. Checking during the winter time in Alaska, and the VOC will likely be higher.

What is a Good Open Circuit Voltage in San Antonio?

When living in hot San Antonio, a high open circuit voltage means more electricity capability and a longer lifespan of the panel – assuming the panel’s equipped to an inverter that can handle it. The reason being a high max capacity of volts allows for a higher electrical current and therefore could produce more electricity for your home. In colder climate areas, too high of a VOC may be dangerous if its inverter cannot handle the respective amount of volts. So in San Antonio, the chances of exceeding the inverter’s limit is less likely. This means your panels are less likely to experience electrical damage than in a cooler climate.

solar rooftop in universal city
Solar rooftop in Universal City

As of 2022, an excellent open circuit voltage is around 30-58 volts. A panel with a VOC of less than 30 volts is likely small with little power output. It’s important to note the VOC is not what makes one panel better than another, but it does reveal a solar panel’s potential in terms of power output and longevity. A solar panel with a VOC of 31 may outperform one with a voltage of 55. However, all other things equal, the latter is likely to generate electricity earlier and later in the day as well as have a longer lifespan.

Is Open Circuit Voltage an Important Factor?

There’s no one, sole criterion San Antonio homeowners should consider before going solar. Instead, multiple factors should be investigated. A reputable solar installation company can help you make that decision based on your specific needs. If Solar Edge Pros had a top five things for homeowners to consider, would open circuit voltage make the list?

No.

It is important for an installation company to consider the value when installing the panels on your property because inverters operate within a set range of volts. However, San Antonio homeowners shouldn’t lose sleep if a solar company wants to install a panel with a lower VOC than another panel. More important factors to consider are: price, warranties, maximum power output, temperature coefficients of Pmax, and efficiency rating.

Texas' Best Solar Installers
Solar installers working in Cibolo

Fortunately, most solar companies today use microinverters, like Enphase Energy, which attach to the solar panel directly instead of a string inverter, like SolarEdge, that can connect to multiple solar panels. Why microinverters? Because if a string inverter breaks, the homeowner’s solar system stops producing a lot more electricity than if just one microinverter breaks. Although it’s rare for inverters or panels to break, it does occasionally happen.

Overall this is a good thing for the company too. It’s safer to install a panel to a microinverter instead of having to calculate the amount of panels to a string inverter. The VOC can also help a solar installer find the best tilt for solar panels being installed on a standalone structure such as a solar carport, solar ground mount, or solar patio. For more information on the subject, please feel free to give us a call or email us at info@solaredgepros.com.

Your Local Solar Installer in San Antonio

Solar Edge Pros is located near North Star Mall in San Antonio, Texas. Since 2014, we have done over 5,000 solar installations. All our jobs are done in-house with no sub-contractors. Schedule a free solar evaluation for your property by clicking the link below.

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Meet The Author

davidm

davidm

David is an Air Force veteran with a Masters in Diplomacy from Norwich University. He is currently Solar Edge Pros' Director of Marketing.

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