FRANKFURT (Reuters) - German solar car firm Sono Motors is exploring a U.S. stock market listing that may value the company at more than $1 billion, people close to the matter said. Sono Motors is developing an electric car that uses solar panels on its outside to power its batteries, but which can also be charged using a plug. The solar panels generate energy worth on average 112 kilometers a week. The company is working with Citi and Berenberg on the listing, which could take place before the summer break either as a classic initial public offering or as a merger with a blank check company (SPAC), the people said. Special purpose acquisition companies raise funds in an initial public offering with the aim of buying a private firm, which then automatically gets a stock market listing. Sono Motors has already confidentially filed for an IPO with the U.S. Securities and Exchange Commission, the people said, adding that the company is in parallel talks with several SPACs about a merger or so called “De-SPAC” deal. Production of the solar electric vehicle with a range of 255 kilometers is scheduled to start in the second half of the year and the company so far has no meaningful sales. It could still be valued at significantly more than $1 billion, one of the people said. Sono Motors was not available for comment, while the banks declined to comment. Sono Motors development partners include Continental, ElringKlinger and RLE International. Financial backers include Swedbank Robur and DNCA, which participated in a late 2020 fundraising round worth 45 million euros. In early 2020, Sono Motors secured 53 million euros from a crowd funding initiative, as prospective customers made down payments for future delivery of the Sion-branded vehicle.