Solar panels are an ideal way to harness the power of the sun. They convert sunlight into electricity through a process known as the photovoltaic effect. Solar panels are connected in series or parallel to meet the desired voltage and current levels of a solar system.
The rated terminal voltage of a typical 12V solar panel is around 17V, this voltage is further regulated by a solar charge controller around 13 to 15 Volts to charge batteries. Sometimes solar panels produce overvoltage due to various factors that can be harmful to the solar power system. This article will cover the possible reasons and their solutions to the solar panel’s overvoltage problem.
Factors Affecting Solar Panel’s Output Voltage
Various factors contribute to the solar panel’s overvoltage condition. Three important factors are briefly described below:
Temperature
The temperature has a significant impact on the output voltage of solar panels. The output voltage of the cell decreases as the temperature rises because heated temperatures cause the cell to deteriorate. Therefore, for every 5°C rise in cell temperature in direct sunlight, the output voltage drops by around 2.5%. With this in mind, it is important to note that if the solar panels are extremely cold due to cloud cover and the sun bursts through the clouds, the output of the panel may surpass its rated output.
Configuration
Solar panels are connected in series to increase and meet the desired solar system voltage. If solar panels connected in series are more than recommended then they will produce too much voltage. For example, if one 12V battery is connected to the solar inverter, it will require a single 12V solar panel to provide around 17V. Furthermore, 17V is then regulated through a solar charge controller to provide 13 to 15 Volts for battery charging.
Compatibility
There are typically two types of solar panels available in the market: 12V, 180W, or 24V, 350W. Choose the right solar panel depending on the energy requirements of a building and other components of the solar system such as solar inverters and solar batteries. Incompatible solar panel selections such as 24V, 350W specifically when the requirement is 12V, 180W will raise the voltage and may damage solar system components.
How to Check A Solar Panel’s Voltage?
The first step to fix the overvoltage problem in a solar system starts with the checking of its solar panel’s voltage by performing an Open Circuit Voltage Test as per the below-given instructions:
Check the voltage level. Then, compare it to the label that is located on the back side of the panel. If they are equivalent to one another or extremely near to one another, then the performance of your panel is good. If found any overvoltage then corrective action should be taken as given later in this guide.
How To Reduce A Solar Panel’s Voltage?
There are 4 different ways to fix the solar panel’s overvoltage problem and all are described below:
Use MPPT Charge Controller
MPPT Charge Controller is perhaps the highest-quality Solar Charge Controller available on the market. The MPPT (Maximum Power Point Tracking) Charge Controller can simply synchronize the voltage between the solar panel and the battery. MPPT charge controllers are designed to optimize the performance of solar panels. Therefore, they contain the capability to dynamically match voltage to maximize ampere output.
MPPT charge controllers are automatically programmed to match the solar panel’s voltage with the system’s required voltage. There are highly efficient MPPTs available in the market that can optimize the solar panel’s voltage, even if the user has used an incompatible solar panel. MPPT charge controllers are costly but will make your solar power system highly productive.
Use Step Down Converter
Step-down converters work in the same way as MPPT charge controllers but are somehow different in functioning. Step-down converters simply step down the DC voltage at one level to the DC voltage at another level. But MPPT charge controllers are intelligent in the sense that they gather maximum power from the solar panels and transfer it to the battery. Anyway, step-down converters are lower in cost but can be utilized for temporary setup.
Reconfiguring the Solar Panels
Reconfiguring solar panels requires some technical expertise and some knowledge of electronics and circuits. Solar panels are connected in two-part wired series to get more voltage out of them. However, if solar panels are producing too much voltage then making the connection parallel can reduce the voltage. This can be done by making some changes to the junction box. This method is not easy and should be done by an expert solar technician.
Replace with Compatible Solar Panels
Replacement of solar panels is the last option if other things do not work. Use only compatible solar panels whose rated voltage matches the battery voltage. However, when you are upgrading your solar power system from 12V to 24V, then you have two choices: either replace the 12V solar panel with a 24V solar panel or add another 12V solar panel in series.
Conclusion
Modern solar power systems work effortlessly without any interruption. However, if the solar panel installed with a solar system produces too much voltage then you have to first diagnose the root cause of the problem. Then choose any of the four strategies to fix the overvoltage issue. Using MPPT is highly recommended, whether you are experiencing an overvoltage problem or not since they optimize the power management within the solar system. Nevertheless, always read the user manual before doing any troubleshooting task. Contact your solar service provider for further technical assistance.
