Levi Yissar was an Israeli engineer and entrepreneur. He built the first prototype Israeli solar water heater.[1] In the 1950s there was a fuel and electricity shortage in the new Israeli state, and the government forbade heating water between 10 p.m. and 6 p.m. As the situation worsened, Yissar proposed that instead of building more electrical generators, homes should switch to solar water heaters. He built a prototype in his home, and in 1953 he started NerYah Company, Israel's first commercial manufacturer of solar water heaters.[2] By 1967 around one in twenty households heated their water with the sun and 50,000 solar heaters had been sold.[2] However, cheap oil from Iran and from oil fields captured in the Six-Day War made Israeli electricity cheaper and the demand for solar heaters to drop.[1] Following the energy crisis in the 1970s, the Israeli Knesset passed a law requiring the installation of solar water heaters in all new homes (except high towers with insufficient roof area). As a result, Israel is now the world leader in the use of solar energy per capita (3% of the primary national energy consumption).[3]