Renkube: Developing AI-powered light harvesting glass to harness the power of the sun

Deeptech solar startup Renkube is developing an AI-powered light harvesting glass that helps panels gather more sunlight and redirect it to solar cells to increase energy yield

By Divya J Shekhar Forbes India Staff

Published: Aug 18, 2023 12:22:55 PM IST

Updated: Aug 18, 2023 12:49:09 PM IST

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(L to R) Lakshmi Santhanam, Balaji Lakshmikanth Bangolae and Deepika Gopal, Co-founders of RenKube at a solar field in Karnataka. Image: Selvaprakash Lakshmanan for Forbes India

While working at Cisco in Bengaluru, three engineers decided to get out of the corporate bubble to use their skills in the promising renewable energy space. They started out with a simple premise—India is still importing billions worth of oil and is not energy-secure. Being a tropical country, can we capture solar energy better? This led them to start a deeptech solar startup called Renkube in 2017.

Balaji Lakshmikanth Bangolae, Lakshmi Santhanam and Deepika Gopal did not have a background in solar and renewable energy, and spent the first few years trying to come up with a business model. Their first endeavour to convert heat to electricity ended in failure after they realised there was no unit economics in it. They spent another two years in research and development. “We wanted to build something that was not done anywhere else in the world,” says Bangolae. They used that learning, and skills from their technology background, to develop an AI-based software that develops the best designs to capture sunlight. Finally, they developed motion-free optical tracking (MFOT) of solar panels.

In traditional large solar farms, the panels are kept on motors and gears, and mechanical trackers help the panels move in the direction of the sun. These trackers come with an additional capex, and also need skilled manpower to maintain them. They are also viable only for huge solar farms, and not smaller residential or commercial spaces. “We have embedded this tracking capability in a completely motion-free manner using glass,” explains Santhanam.

They have designed a patent-pending optics and geometry on a light-harvesting glass to capture sunlight throughout the year and send it to solar cells. “We have demonstrated that this can increase the energy yield of the panel by up to 20 percent. We are now designing to increase the yield further to 40 percent,” she says. “We give the same benefits of a mechanical tracker, but in a completely motion-free manner so that you do not have the hassles associated with a tracker.”

While developing this, they made sure the glass is able to redirect light without damaging the solar cells or creating hotspots on the panel, and illuminates every cell. They can retrofit this to suit specific requirements. “You give all boundary conditions and our proprietary artificial intelligence (AI) software comes up with the best geometrical design of the glass,” Santhanam says.

Bangolae says they are also currently looking to collaborate with solar panel manufacturers to help manufacture their technology. The Renkube panels will cost up to 10 percent more, but the investment can be recovered in a year or two due to the 20-40 percent increased solar yield, Bangolae says, adding that paid pilots for this technology are expected to start early next year. The use cases for these panels can be in residential and commercial buildings, as well as agri photovoltaic (PV).

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The startup currently has an ongoing agri PV pilot at the Professor Jayashankar Telangana State Agricultural University (PJTSAU) in Telangana, conducted under the guidance of the AgHub Foundation. They have studied data over one crop cycle and will conduct another year of studies. In existing agriPV set-ups in the country, when solar panels are used in an agriculture field, there is an assumed loss of crop yield of 30-40 percent, Bangolae explains. In such a setup, usually only shade-tolerant crops can be grown as these panels cause a shadow underneath. “We realised that our panels cause minimal shadow because of their design, which means we can grow tropical crops. So there is no yield loss, and the land can be used for both solar and agriculture,” he says. “The light redirecting prisms on the panel also send excess sunlight that is not required by the solar panel to the ground beneath, which also helps in crop growth.”

Renkube has so far raised seed funding as a mix of equity and grant money, of about Rs 5 crore ($570,000), and are looking to raise Series-A next year as soon as their products are commercialised. Their backers include Halliburton Labs, CIIE.CO, JITO Angel Network and K4 Forum Mumbai Network. Government grants like IISc-MSME, BIRAC, USISTEF have also been instrumental in their product development, says Bangolae.

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“When we invested in them [in 2021] nobody was thinking of re-engineering on the glass side. What they were doing seemed to be disruptive in a space where nobody was thinking beyond putting up EPC (engineering, procurement, construction) power plants, data analytics or at best robots to maintain solar panels,” says Chintan Antani, vice president-seed funding at CIIE. He believes that the product has bright commercialisation prospects.

According to him, the co-founders bring an outsider’s lens to the renewables space and do not come with pre-conceived notions about doing business. “This makes them better at absorbing feedback. They are extremely coachable, and focused on what they want to do. They understand that this cannot be hurried up and are cognizant of the partners they choose to bring on board.”