Solar-Homes both Passive and Active according to all evidence can be a very good investment, depending on energy needs, these homes are usually designed with the sun in mind. The Passive homes are homes that are designed to provide heat, light, and cooling, and this is done without the help of any mechanical devices, while the Active homes heats, cools, and uses electricity through the use of solar electric systems.
These Solar-Homes start by being well insulated and solar positioned, with no obstacles to block the sun's rays. The windows, walls, and the floors in these Passive Homes are used to collect, store, and distribute the sun's energy. Windows are selected, oriented, and glass sized to control heat gain, depending on the climate. The glazing of these windows is done to maximize solar heat in the winter, and to minimize it in the summer. Oriented towards the sun, they can provide natural lighting and heating.
Overhangs on these homes should shade south-facing windows in the summer and allow more heat gain in the winter. If more shading is needed, landscaping, shutters and screens can be used.
Other very important elements needed for passive home designs are walls and floors using Thermal Mass. Thermal Mass consists of materials such as brick, stone, ceramic tiles, and concrete. These materials can absorb and store solar heat, and release it slowly when needed. Also, depending on where you live and on how well designed and insulated your Passive Home is, will determine if any other form of heat other than solar will be needed.
Through the use of solar electric systems, Active Homes can cool, heat, and use electricity. Solar-homes can be connected to the electric grid or to a stand-alone system, where unlike passive systems, they can maximize their effectiveness by utilizing mechanical devices (usually electrical).
Stand-Alone Systems being off-grid, must be able to meet energy requirements. This means that a photovoltaic system, must be able to generate enough energy from the sun to store it in batteries and use it when needed. Gas powered generators can also be combined with wind turbines to act as back-up power.
Heating Active Homes is done by the use of solar thermal energy, such as Solar Collectors which are used to collect energy by absorbing sunlight, and then using it to heat or to cool buildings. Solar thermal and photovoltaic can be paired together to increase the efficiency of a typical (PV) System.
See Alternative Energies for more information