A high irradiation level makes the Osmanabad district of Maharashtra, India the preferred choice for setting up a solar PV plant. However, the region poses challenges of uneven terrain and high ambient temperatures, which could impact the modules’ power output and inverter performance. Keeping these challenges in mind, Navalakha Translines decided to install Growatt’s string inverters with auto cooling for its 6 MW ground mounted solar PV system.
The plant is providing significant power generation with 30,000 kWh of daily output, across 300 sunny days each year. Navalakha Translines feeds all power generated into the grid, and sells energy to different organizations under open access.
“Dependability, quality, easy installation, after-sales service and presence in the market—all these points work in favor of Growatt,” said Navalakha Translines founder Satendra Navalahka.
Another advantage of Growatt inverters is their integrated cloud-based communication platform system. This allows the plant owner to see instantaneous output of each inverter on his mobile, and in the case of error, call site engineers to check a particularly weak inverter’s performance in comparison to others.
Why string?
Based on his experience with Growatt inverters, Satendra Navalahka recommends the use string inverters, when cost comparable with central inverters.
“One advantage with string inverters is that civil work is reduced. You can complete installation and start generation within three months, as compared to central inverters which require significant work, such as setting up a room, etc.” says Navalahka. “Further, the failure and maintenance loss is much higher for centralized inverters than string inverters. Even if a string inverter fails, you don’t lose much generation.”
The company founder says that after-sales service and repair of string inverters is also easier than central inverters, which supported Navalakha Translines’ decision to choose string inverters for the plant.
How self-cooling works
To manage the temperature of internal components, the cooling system needs to be efficient. As ambient temperatures in Osmanabad reach up to 45 degrees Celsius during summers, the inverter temperature would be higher than that as all the insulated-gate bipolar transistors (IGBTs), or internal components which convert DC into AC, are working continuously for 10-12 hours per day.
The Navalakha project specified 84 Growatt MAX 60 kW PV inverters. The inverters come with a self-cooling mechanism, equipped with IP67 fans to avoid overheating. Further, if you place these inverters in an outdoor environment, they are inherently protected from the elements, such as dust and rain.
“All these fans work at a preset temperature. This means the first fan will start only when the temperature of the inverter crosses a particular level, also the fan speed will increase with the temperature rise. The second fan will start if the temperature increases beyond a threshold level,” explains Shantanu Sirsath, Growatt’s technical head for India. “We have set two threshold levels for the fans to minimize the consumption from the DC-source panels.”
He added that the lifespan of Growatt inverters covers around 25 years under favorable conditions, which is equivalent to the lifetime of the solar plant. These values were then factored into their design decisions for the project.
Cloud-based communications
For large-scale projects such as the Maharashtra 6 MW plant, Growatt provides a special monitoring device called Shinemaster. With this single device, one can monitor 32 inverters through RS485 connection. In the case of Navalakha Translines’ system, the device is being used to monitor 18 inverters.
Shinemaster collects all the data of individual inverters and sends it to a server. A special login account allows for Satendra Navalakha to monitor the performance of his whole plant as well as that of individual inverters from his office or any remote location around the world. If there is an error alarm, it will be displayed on the portal. Directly from the monitoring page, it is possible for system owners to determine which particular inverter is giving what sort of error.
“It’s easy for our service engineer to ascertain whether the problem is due to voltage issues, hardware failure, or something else,” says Growatt’s Sirsath, adding “The next preventive action will be that our engineer visits the site and repairs the inverter or provides a replacement, if required.”
Remote service possible
The Growatt portal also provides remote online service, for example, remote updates to inverter and datalogger firmware, preset inverter parameters etc. According to Growatt service engineer experience, more than 60% of service issues could be solved online, which obviously reduced on-site service time and cost, and is much more convenient for customers.
The whole package
Looking forward, Navalakha Translines will use Growatt’s 253 kW string inverters for its next plant of 10 MW, also in Maharashtra. The company says it is also developing a new plant in Himachal Pradesh, that will also specify Growatt’s inverters.
“Growatt’s presence in India, and their capability to offer different capacities of inverters, continuous research and development, good after-sales service – and above all else – a good combination of features with price advantage is why we prefer Growatt inverters,” said Navalakha.
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