The paper presents some aspects of solar radiation conditions in Poland and solar energy availability. Data for solar radiation on surfaces with different slope and orientation are important for elements of a building an envelope, as well as for solar collectors of active heating systems. Heating/cooling needs of a room depend strongly on room location, which is a result of solar energy impact. Solar energy can be used for passive heating in winter, spring and autumn, especially by the south facade. In summer, shading is necessary and problems of overheating because of too much solar gain are evident at attics. Solar energy also can be effectively used for active heating. Types and solutions of solar active heating systems are described. Prospects for solar system development are analyzed.