Jaipur: Discoms are inviting bids to install 3 lakh rooftop solar systems, allotted by the Centre, for low-income and vulnerable households under the Utility-Led Aggregation (ULM) scheme. Project developers, however, have raised concerns over thin profit margins.Each rooftop system will have a capacity of 1.1KW and is estimated by discoms to cost Rs 60,000. These will be provided free of cost. Under the scheme, each of the three discoms will cover 100MW — equivalent to 1 lakh households.The govt has estimated that each discom will spend Rs 600 crore. While they will receive Rs 33,000 in central financial assistance per system, they will contribute the rest of Rs 27,000 from their own funds to meet the Rs 60,000 cost.At a pre-bid meeting Wednesday, discom officials clarified that projects must be commissioned by March 2027 — within six months of the letter of award. Failure to meet the deadline will attract a penalty of 1% of the deposited guarantee money.Vendors argued that rising prices of domestically manufactured solar panels make the Rs 60,000 estimate unrealistic.“As per our calculation, the total cost comes to around Rs 58,500. But with the requirement to deposit a bank guarantee of Rs 1.2 crore for the minimum lot size, and factoring in interest costs, the actual expense exceeds Rs 60,000. Without at least a 10% margin, no developer will be interested,” said Ajay Yadav, president of Renewable Energy Association of Rajasthan.He also flagged concerns about lot sizes, which range from 2,000 households to 15,261. “This is too high, and many vendors will not be able to participate in the tenders,” Yadav added.Recently, Chief Secretary V Srinivas held a series of review meetings after the Centre expressed concern over the slow progress of the scheme.