• Reliable and cost-effective electricity generation, independent of an existing grid
• Easy to install and robust design with no moving parts
• A wide range of applications from very small systems to large-scale installations thanks to modular structure
• Quiet electricity generation
• Silicon as primary material is common, inexpensive and easily recyclable
• Low maintenance requirements

First, it is generally differentiated between crystalline wafer-based technology, consisting of mono- and polycrystalline silicon cells, and thin-film technology, modules made of copper, indium, gallium and selenium or amorphous silicon.

PV cells consist of one or more semiconductor materials and enable solar energy to be converted directly into electricity. Chemical elements are added to produce two layers, a p-conductive layer with a positive charge carrier surplus and an n-conductive layer with a negative charge carrier surplus. Due to this imbalance, an inner electric field is formed which acts as a barrier layer. Light incident on the cell then produces a charge separation. The charge carriers released in this process can be conducted through contact with metal and used as direct current by an electrical device or fed into the grid as alternating current via an interconnected inverter. To provide higher capacities, PV cells are interconnected in modules.

Domestic use

Most domestic systems are rooftop installations, however, there are new ways of integrating PV systems into a building itself, e.g. by embedding PV into the roof, facade or windows. To meet the annual consumption of a four-person family in Germany, an average household needs a PV system with a peak output of 3.5 to 4 kW. Depending on the PV technology used, this corresponds to a solar panel surface area of about 35 to 40 m². In areas with higher solar radiation, less surface area is needed. Intelligent energy management and storage technologies can be used to optimise the consumption of self-generated PV electricity.

Industrial and commercial use

The roofs of factory buildings, production facilities and commercial complexes provide enough area for larger on- or off-grid PV systems. Hybrid systems allow for combining PV systems with other renewable energy technologies or diesel generators and storage devices.

Large grid-connectes systems vs. mini-grids

Typically, large grid-connected systems are designed as ground-mounted systems or as large rooftop installations. Systems of this type can be used to power municipalities or other large consumers or stand-alone power systems (mini-grids). In the case of mini-grids, several PV systems feed into a stand-alone power system, allowing it to provide electricity for several houses or even entire villages. Typically, hybrid systems are used in this case. In order to maximise the generation of solar electricity and the yield benefit, sun-tracking PV modules can be installed.