Production of electric current from Solar Radiation. In Solar Cells, usually made of silicon, positive and negative charge carriers are freed when light strikes the cell (Photoelectric Effect). In this manner direct current (DC) is produced which can then be used to directly power a motor or can be stored in a Battery. If Solar Energy is to be used by consumers with 110 V alternating current (AC), or fed (“sold”) directly into the grid (Grid Coupling), then an Inverter is needed. Advantages of photovoltaics include its clean, “ecological” electricity production and the possibility to provide consumers with off-grid, or grid-independent, power (Off-Grid System), i.e. at a weekend home, in a garden or park, or to light small covered waiting areas. The relatively high costs are an important disadvantage when compared to a Solar Heating System--the price/output relationship must constantly be monitored (today it is about $ 4 / Wp.)

Solar power and heating systems can generally be installed without planning or building permission; they are not referred to in the Building Law Book. However, there has always been conflict with the protection of historic buildings because solar power and heating systems can change the outward appearance of a building and therefore interfere with the character of a protected building or other structure. Legal permission to build and legal permission to make changes to a historic building or monument often fall on the competence of the same (local) officials.

Whether or not a solar power or heating system is given the go-ahead depends mostly on the discretionary authority of the local authorities. The submitter should be able to state that any adverse appearances are not substantial and that such solar power and heating systems belong to today’s standard equipment for buildings, just like antennae, noise-blocking windows or garages.

Submitters can especially appeal to the Changes to Building and Space Arrangement Law of 1998. After that it is one of the tasks and principles of urban land use planning. “The concerns of environmental protection, also through the use of renewable energies” to take into account (§1 Paragraph. 5 Sentence 2 Nr. 7 Building Law Book).

Although alternative technologies have been developed and are now fit for use, only a small share of primary energy and about 10 % of electricity comes from Renewable Energy Sources, yet the use of geothermal, wind and Solar Energy sources is vital for the protection of the environment. In addition a sustainable power industry has a positive effect on the job market.

Due to these reasons, the use of renewable energy sources is promoted by communities, states, countries, and the European Community. The German Renewable Energy Law , adopted by numerous countries, ensures feed in tariffs for electricity from photovoltaic systems; a market stimulation programme offers subsidies for solar thermal systems.

According to the Renewable Energy Law, grid operators must pay a minimum of 46,30 Euro Cent/kWh in 2007 – up to 54 Euro Cent/kWh for smaller façade pv-systems for electricity generated from Solar Radiation energy provided to the utility grid (Grid Coupling).

Illustration: Heindl Server GmbH

Solar electricity and Thermal Solar Use are both promoted by the German Federal Government: The German Renewable Energy Law , adopted by numerous countries, ensures feed in tariffs for electricity from photovoltaic systems; a market stimulation programme offers subsidies for solar thermal systems.

Solar roof tiles from the Firma Laumanns, Brueggen, as an aesthetic alternative to conventional photovoltaic systems. Laumanns GmbH, Brüggen

The protection of historic buildings, districts and monuments should preserve the ownership of cultural goods and property, and more specifically, it should protect against destruction or changes brought about by private, commercial, or public interests. The protection can pertain to single objects (i.e. buildings) or to entire ensembles (i.e. districts), and such protected objects are listed in a historical building and district book.

In Germany the protection of historical buildings, districts and monuments is the responsibility of the states (State Monument Bureau); in Austria and Switzerland such protection is covered under federal law. Communities and counties include departments for historical building, monument and district protection in either the building bureau or the planning bureau. City and town statutes offer further protection for historical buildings, monuments and districts at the community level.

Solar power and heating systems of all kinds come into conflict with such protection ordinances or statutes because these systems change the outward appearance of buildings. Every individual case must be closely examined, and the contact person is almost always the corresponding local authority. A party using a solar power or heating system should consider that he usually won’t have problems obtaining a building permit, but could very well have a problem obtaining approval for the appearance of his system because of these protection laws. He should be able to demonstrate that any optical nuisance caused by his system is not considerable and that in today’s world, solar power and heating systems belong to the standard equipment afforded to buildings, just like antennae, noise-preventing windows or garages.

Not only the abbreviation for photovoltaics. The term is composed of Photon (Hellenistic for light) and the name of the physicist Alessandor Volta (1745 – 1827), at his time one of the leading scientists in the field of galvanic electricity (chemical procedures as for instance while immersing metals into acid. He constructed the first electrical battery in 1780.

The abbreviation is often used in combinations such as PV-System or PV-Module.

Related terms: Photoelectric Effect

Combination of a photovoltaic module (left) and a flat-plate collector. Picture: MBW.NRW

PV = Photovoltaic. A photovoltaic, solar, or PV module consists of many interconnected Solar Cells which are embedded between two glass or plastic plates to protect them from weather. PV modules are normally mounted on top of a roof (Roof-Mounted Solar Power System), or a holding rack of some sort, within a frame structure. Modules are delivered for standard voltages, i.e. 12 V.