This paper goes through solar energy and what uses it has. It is also a guide in the choice of solar collectors for the real estate that I have drawn for the thesis work. Solar energy is a renewable source of energy from the Sun's light. Energy can be used to produce both heat and electricity through solar collectors and solar cells. Some of the benefits of solar energy is that it is completely free to extract, environmentally friendly and virtually maintenance-free. Disadvantages are that the technology is expensive, does not cover the entire energy needs and takes a long time until it pays. Solar heat is extracted through a solar collector, usually a flat solar collectors or vacuum isolated solar collectors. Solar electricity is extracted usually by photovoltaic cells but also with the help of thermal processes. There are different types of solar cells in which crystalline silicon solar cells are the most common. Because I want a solar collector to cover a large part of the heating for hot water throughout the summer, I have mainly singled out more models that I compared with each other. I decided to choose GJ140D.5 by Sunmark A/S because it is the most affordable in relation to efficiency.