What is the difference between solar thermal collectors and a photovoltaic power system?

Solar thermal collectors are used to heat water, mainly for household use. Photovoltaic systems generate electricity.

What is the difference between grid-connected and off-grid?
Grid-connected applications can feed electricity directly into an electricity network. Off-grid systems often have batteries to store the electricity produced and have no access to the electricity grid.

Do we have enough silicon as raw material?
The raw material silicon used in the PV industry is abundantly available worldwide. However, the process of producing the pure silicon needed for crystalline solar cells is complex. It can take two years from planning a new silicon factory to its first output. The dynamic development of the PV market has led to a shortage of pure silicon, and the industry has reacted by building new capacity. These new factories improve the supply situation.

Is it possible to recycle photovoltaic modules? Yes, all components in a solar module can be
recycled. The most valuable parts are the solar cells themselves, which can be recycled into new wafers as the basis for new solar cells. The aluminum frames, glass and cables can also be recycled. For more information: www.pvcycle.org

When will PV be cost-competitive?
In many cases solar electricity is already cost-competitive, especially for stand-alone applications where no access to the public grid is available. In southern Europe, grid-connected photovoltaic electricity will be cost-competitive with peak power by 2015. PV prices are expected to continue to fall.

Do PV systems generate more energy over their lifetime than is needed for their production?
Yes. After approximately two years, a PV system in southern Europe based on crystalline technology will have generated as much energy as was needed to produce and install all its components. For a thin film system, the period is about a year. Over a PV system’s lifetime of more than 30 years, it will produce far more energy than was used to create it. The energy used in PV production is continually being reduced.

Is PV only efficient in southern countries?
No. PV works everywhere where there is light. Even in southern Germany, an average sized roof-top system of 3 kW generates close to 3,000 kWh annually. This could cover the annual total electricity demand of a single household.

Is PV expensive?
The electricity generation costs for PV systems are currently higher than for other energy sources, if the environmental costs of conventional electricity generation are excluded. Financial support is therefore needed to develop a strong industry with economies of scale. With large-scale production, prices are expected to fall below residential electricity prices and will also compete with the generation costs of all other electricity sources (nuclear, fossil) within 20-30 years. In countries with feed-in tariffs, PV is already a very attractive investment.

Is there enough space to install a large number of PV systems?
Yes. PV is a space-efficient technology. For a 1 kW system about 7 m2 of modules are necessary. In order to cover the entire electricity demand of the EU, only 0.7% of the total land area would be needed. There is a huge area available which is not competing with other land uses, including roofs, building façades, noise barriers and vacant plots. Space availability is not a limiting factor for PV development.

How long is the lifetime of a PV module?
Many producers give performance warranties of 20-25 years for their modules. At the EC Joint
Research Centre in Ispra (Italy), crystalline modules have been operating in a field test, with excellent performance results, for more than 20 years. The majority of the modules continue to exceed 92% of their nominal power output as recorded at the beginning of the testing period.

How much space do you need to install a roof-top system?
This depends on the technology used. A 3 kW system based on crystalline modules needs about 23 m2 of a sloped roof area facing approximately south.

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