Robotic Cleaning Can Maximize Energy Yield & Reduce O&M Cost of Solar Projects

The payback period for a robotic cleaning system is 18-60 months


Solar power projects need efficient operations and careful maintenance after being commissioned to maximize energy yield through the project’s useful life.

Dust and dirt that settle on solar modules reduce the amount of light hitting the module and its output over time. The estimated energy output figures claimed by module manufacturers, and project developers are based on the optimum performance of clean modules. The build-up of dirt can adversely affect the modules’ ability to meet those projections.

The traditional method of cleaning modules uses water to wash them manually using human labor. Water scarcity, expensive labor, and solar projects located in arid, drought-prone regions have made this process expensive and unviable.

To tackle this issue, the solar industry has been shifting to robotic cleaning technologies, which provide a cost-effective method to clean solar panels compared to manual cleaning. Robotic cleaning solutions are gaining acceptance amongst utility-scale solar developers because of their efficiency and cost-effectiveness.

To understand the benefits of robotic cleaning and how it can optimize the operations and maintenance (O&M) process of solar projects, Mercom Communications hosted a webinar titled ‘O&M Innovations: Optimum Management of Solar Assets’ on July 19, 2022.

The panel included Nalin Kumar Sharma, President-Asia, Middle East, and Pacific, Ecoppia; Ritesh Singhi, COO-C&I Business, Amp Energy India; Harshal Akhouri, Co-founding Director, Strolar; Saurabh Mehta, Head (BD and Project), Mahindra Susten. Priya Sanjay, Managing Director, Mercom India, moderated the session.

The webinar began with Sharma explaining the factors driving the demand for robotic cleaning in India. He said, “India is a very cost-sensitive and value-driven market. From our experience, a few factors drive the demand for robotic cleaning in India—one of them is getting more from the same asset over time. As manual cleaning takes place with a gap of a few days, the generation from the modules will be sub-optimal. Whereas robotic cleaning happens every night, and panels can have optimal generation the next day.”

“The other factor is the uncertainty regarding the availability of manual labor. During the last lockdown, several projects faced difficulties cleaning their modules for almost 150 days. As robotic cleaning is independent of manual labor or even maintenance staff, developers need not fret about such situations,” Sharma said.

Increased demand

Sharma commented on the reason for the shift to robotic cleaning systems, “The focus on robotic cleaning is not only restricted to drier states like Rajasthan and Gujarat. We have clients from states like Madya Pradesh, where the government has been offering free water for 25 years. The main difference is the 24 cleaning cycles in manual cleaning versus the 365 cleaning cycles offered by robotic cleaning systems. This translates to a generation gain of 2% to 5%.”

“Also, what we have seen is the cost escalation. When we entered the Indian market in 2016, the cost of cleaning a single module was close to ₹0.40 (~$0.0050). This figure currently stands at over ₹1 (~$0.013), an increase of over 250%. No developer had considered more than a 4-5% increase in module cleaning cost. This increase in cleaning costs is due to the inflating cost of manual labor. Robotic cleaning helps in this regard because by eliminating the cost of manual labor, a robotic cleaning system will pay itself back in 18-60 months. We have an IRR north of 20% in many cases,” Sharma added.

Industry’s take on Robotic Cleaning

Commenting on Amp Energy’s experience deploying robotic cleaning systems in an existing solar project, Singhi said, “There are certain challenges in deploying robotic cleaning systems in existing solar projects due to the smaller sizes of the old modules. Sometimes, we must build a new docking system to facilitate the robot. However, given the O&M cost reduction, developers are moving to robotic cleaning solutions for their existing projects despite the relatively higher capital expenditure. Bridging the gap between the tables would be the biggest challenge, in my opinion.”

Mehta feels the developers must consider multiple aspects when installing the robotic solutions, which are constantly evolving. “Robotic cleaning systems have matured and are delivering what is promised. However, developers must factor in the cleaning frequency required, the size of the project, the type of mounting structure, and the length of the table. A developer must also see if the robotic cleaning system is compatible with the module they are using. If the developer has factored in all the aspects, then in our experience, robotic cleaning systems are very effective.”

Commenting on the design requirements needed to deploy robotic cleaning systems at utility-scale projects, Akhouri said, “Certain basic design requirements depend on whether the system is framed or frameless. You should also check if the docking station of the cleaning system is an extension of the existing mounting structure or if it requires a separate mounting system. The other factor to consider is the table-to-table distance under the rollover distance of the cleaning system.”

“When it comes to retrofitting, the older projects designed with inverter sizing mean smaller tables leading to more tables when deploying a robotic cleaning system. This can increase the capital expenditure,” Akhouri added.

Capacity expansion

“Per our figures, more than 60-70% of greenfield projects are commissioned with robotic cleaning systems. In the case of brownfield projects, 40-50% of them will be retrofitted with robotic cleaning. Our latest model, Ecoppia H4, cleans from either side of the row, minimizing the time spent on the panels. When we started, the table lengths were 300-400 meters, but we currently see more than 1.5 kilometers long tables. This effectively means a single robotic cleaning system can clean over a megawatt of modules.” Sharma said.

Commenting on the production capacity of Ecoppia, Sharma said, “In the next five years, we see ourselves supplying robotic cleaning systems to anywhere between 35-40 GW of projects globally. The factory we have set up is working at 10% capacity and is producing robotic cleaning systems capable of cleaning 15 GW of solar projects. However, we can expand to cater to 150 GW of solar projects in a phased manner, as and when required.”

Mercom had earlier spoken with Nalin Kumar Sharma regarding the application and the future of robotics in the Indian solar sector and Ecoppia’s products and plans for the coming years. You can watch the interview here.

Image credit: Ecoppia.