Solar thermal energy is energy collected from the sun and used to generate heat. This heat is usually concentrated using mirrors, then used in heating water. Consumers use hot water in residences or businesses, or heat it until it turns into steam used to turn turbines, generating electricity. While solar thermal energy has many advantages, especially environmental ones, it has drawbacks, too.

Unlike energy generated from fossil fuels, such as natural gas, petroleum and coal, solar energy is infinitely renewable. This makes the technology more reliable over the long-term, freeing owners from worry about replenishing it. The use of solar energy can make countries more energy-independent by reducing the energy they have to import.

Save for the pollution expended in the manufacturing of the solar thermal energy device itself, solar thermal energy produces almost no pollutants, such as toxic chemicals or greenhouse gases. With increased concerns about the negative effects of climate change, solar thermal energy provides a safe alternative to traditional energy sources, most of which emit heavy carbon loads. Unlike the heat generated by the burning of natural gas, the heat generated by solar thermal power produces no carbon emissions.

After its initial installation, solar thermal energy is generally low maintenance. Unlike devices that produce energy from coal or natural gas, users can leave solar thermal energy devices alone for long periods after installation. It takes smaller work crews to run solar thermal arrays than more complex electricity generating facilities. Many solar thermal devices, especially those that heat hot water, involve simpler technology than photovoltaic panels.

As of 2010, it is more expensive to producing solar energy than power from traditional fossil fuels, such as coal and natural gas. Generally, steam produced from the burning of coal, oil and natural gas is cheaper than steam produced from solar thermal energy. The start-up costs of solar thermal energy devices are usually higher because of the greater expense per unit of energy generated. However, because solar thermal energy lacks a feedstock, in some situations it may be cheaper over time.

Devices cannot generate solar thermal energy with the consistency of most fossil fuels, and cannot usually produce solar energy on cloudy days, or after dark. This makes it an unreliable source of energy and contributes to its expense, as those relying on solar energy must have back-up power sources.

Unlike fossil fuels, we cannot easily store either sunlight or hot water. This contributes to its unreliability, as users are unable to produce large amounts of energy for later consumption or for emergencies. While electricity generated by turbines can be stored in batteries, the storage is costly and inefficient. Hot water cannot be stored for long periods without a large loss of heat.