Rooftop Solar: Top 5 Mistakes To Avoid In Inverter Installations

If solar PV modules are the brain of your solar PV module then the inverter is the heart of your solar PV module. Understanding inverter installation is utmost important for an error free rooftop Solar PV installation. This not only protects the rooftop solar PV from damage but also improves the efficiency.

However, in the dearth of information and incorrect installation strategy often end up happening. We spoke to Lucky Aggarwal, co-founder Solar Saarthi on how correct installation practices can help avoid these mistakes. Here are the top-five mistakes one can avoid while installing an inverter for their rooftop solar PV module. Aggarwal uses a GoodWe DNS Series 4.2kW residential inverter in his explainer video here.

Use of the installation manual

Going through the installation manual is critical for any kind of appliance installation. So is the case with inverter installation for rooftop solar PV. Explaining the importance of ‘Installation manual’, Aggarwal explains, “Maximum faults with the inverters are due to neglecting the manual which the manufacturer provides. Every reputed inverter manufacturer provides a user manual for their inverter. These manuals are also available online. One can get all the information on how to correctly install and commission this inverter, the width of AC or DC cable compatible with the particular inverter, the angle at which it should be installed, the distance with other inverters and wall etc.”

Thus, reading the installation manual thoroughly is strongly recommended to the users to follow these user manuals, says Aggarwal.

Importance of DC connectors

DC connectors and their proper connection is important for a rooftop solar PV installation strategy. Every inverter manufacturing company provides spare PV connectors. Despite this, crossmating (using connectors from different brands or types) of connectors is still very common, says Aggarwal.

Explaining how crossmating can lead to DC arching, Aggrawal says, “One should always refrain from crossmating of DC connectors during solar rooftop installation. So as an installer, one should only use the spare connectors provided by the inverter company. If we crossmate the PV connectors, then the chances of DC arching increase.”

It can even possibly lead to fire incidents in your project. Thus, damaging the inverter. Interestingly, if the inverter gets damaged due to crossmating of connectors, the insurance claim also becomes difficult.

“If your manufacturer is not providing spare connectors or they get misplaced on site then you can demand these spare connectors from manufacturers and only use those connectors,” advises Aggrawal.

Not paying attention to the internal temperature

An inverter’s efficiency depends on its internal temperature. With the rise in the internal temperature, the inverter efficiency starts declining. Low efficiency means a fall in the performance of the inverter.

“Never install the inverter under direct sunlight. If the inverter is installed under direct sunlight, the internal temperature of the inverter starts rising and its efficiency declines. Always install the inverter in a well ventilated space. So, the internal temperature is maintained due to natural air flow,” recommends Aggrawal on how to control the inverter’s internal temperature for better efficiency and performance.

String voltages for inverter operations and safety

Inverter manufacturing companies specify a particular voltage for a particular solar PV installation. Keeping the maximum string voltage in mind, while installation is critical. As going beyond it could damage the inverter. “If there’s an issue with the string voltage, it will either shut down the inverter or its MPPT will not operate with full efficiency. The other important bit is the string size and its impact on temperature. As with the rise in ambient temperature, solar PV module output voltage starts declining. Similarly, with the decline in the ambient temperature, the solar PV output voltage starts increasing,” says Aggrawal.

Thus, the impact of temperature due to ambient temperature should always be considered while deciding the string voltages. So, the MPPT and inverter can operate with full efficiency, explains Aggarwal.

Impact of Surge protection Device (SPD) on inverter operations

Explaining the impact with an example Aggarwal explains, “Let us assume, a project has two strings. The first string is under shadow for some time while the other one is shadow free. In this scenario, it is recommended to use a double MPPT inverter. So that the string one can be connected to one MPPT while the other string to the second MPPT. This will help both the strings operate on individual MPPTs.”

Otherwise if we install a single DC SPD with the inverter then we bring both the strings in a parallel connection. Thus, the impact of shadow on string one will be on the other string as well. Thus, we won’t be able to benefit from the double MPPT feature. Thus, you should always connect a string to an individual MPPT. Doing this can improve the efficiency and performance of your inverter, suggests Aggarwal.