A photovoltaic system with a conversion efficiency of 10 percent can generate about 180 degrees of electricity per square meter of area. A photovoltaic power system rated at one kilowatt can generate about 1,800 degrees of electricity per year. Allowing for an annual efficiency loss of less than 1%, such a system could generate nearly 36,000 degrees for 20 years and 54,000 degrees for 30 years. This means that over 30 years, the photovoltaic system produced about $10,000 worth of electricity. In many countries, solar power is available at preferential prices, along with other incentives and tax incentives, to improve the economic performance of photovoltaic power.