(Adds detail, CEO quote) MADRID, May 4 (Reuters) - Shares in Ecoener fell on their market debut on Tuesday after the Spanish renewable energy group slashed the size of its offer due to limited appetite, sending a potentially sobering signal to others seeking to list in the sector. Ecoener’s initial public offering (IPO) tested a market that expects listings from several green energy firms, including a unit of Spanish peer Acciona which could be valued at more than 8 billion euros ($9.6 billion). Shares in Ecoener, which develops and manages hydropower, solar and wind installations, fell as much as 5% in early trading, taking their value below the 5.90 euros pricing that had valued the firm at 336 million euros. Ecoener reduced the size of its offer because of limited demand, despite global interest in renewables and the effort to cut carbon emissions. Luis de Valdivia, Ecoener’s founder who had been the sole shareholder, said the buyers were mainly long-term investors who specialised in renewable energy. Most were from Northern Europe and Britain, with 40% from Spain, he added. “Perhaps there was lower take-up from institutional investors in Spain,” he told a news conference on Tuesday. The deal followed a direct listing last week by insurance firm LDA, whose shares jumped on their debut and have held around 20% above their listing price. LDA sold no fresh shares, making Ecoener the first firm to carry out an IPO in Spain since October. Hot on Ecoener’s heels, fellow Spanish developer Opdenergy is taking orders for an IPO aimed at raising 375 million euros. Societe Generale acted as global coordinator for Ecoener, with Banco Sabadell, Caixabank, Credit Agricole and HSBC as joint bookrunners, and Banco Cooperativo Espanol co-lead manager. $1 = 0.8326 euros Reporting by Isla Binnie; Editing by Edmund Blair Our Standards: The Thomson Reuters Trust Principles.