NEW DELHI: The solar power tariff fell to an all-time low, with Finland-based energy firm Fortum Finnsurya Energy quoting Rs 4.34 a unit to bag the mandate to set up a 70-mw solar plant under NTPC's Bhadla Solar Park tender."This (Rs 4.34 a unit) is the lowest solar tariff so far in India. This has happened because of confidence in the balancesheet of NTPC and solar parks that come with all clearances and confidence in the market," New and Renewable Energy (MNRE) Joint Secretary Tarun Kapoor told PTI.In November last year, the solar power tariff had touched an all-time low of Rs 4.63 per unit following aggressive bidding by the US-based SunEdison, the world's biggest developer of renewable energy power plants.NTPC bid out 420 mw in six blocks of 70 mw each, Kapoor said.The other winners included Rising Sun Energy Pvt Ltd (two blocks for Rs 4.35 a unit), Solairedirect (two blocks for Rs 4.35 a unit) and Yarrow Infrastructure (one block for Rs 4.36), Kapoor said."We understand that we are among the successful bidders in the e-reverse auction process conducted by NTPC for the selection of grid connected solar PV projects... in Bhadla Solar Park Phase II in Rajasthan for 70 mw," Fortum India MD Sanjay Aggarwal said in a statement."Based on the general procedure, a letter of intent (LoI) shall be issued within 15 days from the completion of the reverse auction and PPA shall be signed within 30 days after the LoI is issued. Hence, Fortum will be in a position to disclose more details once the company signs the PPA with a relevant authority in India."SunEdison had won a bid to sell solar power from a 500 megawatt plant in Andhra Pradesh under the Jawaharlal Nehru National Solar Mission at Rs 4.63 per kilowatt-hour (kwh or unit).SunEdison had offered tariff lower than SoftBank Group Corp of Japan and Chinese solar product maker Trina Solar Ltd in the auction, industry sources said.