Solar power is needed as an alternative to fossil fuels because many areas lack access to fossil fuels and their combustion causes greenhouse gas emissions that lead to climate change. Some countries have depleted their natural resources through practices like deforestation. Deforestation can cause problems like erosion and mudslides. Solar energy technologies like solar ovens, water heaters, and photovoltaic panels provide solutions and are used around the world. The amount of solar energy available at a location depends on factors like latitude, longitude, temperature, time of day and year. About half of the sun's energy reaches Earth's surface but the exact amount accessible varies by location.