The generation of electricity by means of photovoltaics (PV) in connection with the use of wind energy represents a central component for the future energy supply, not only in Germany, but worldwide. The direct conversion of solar energy into electricity is efficient, its application is simple, scalable, emission-free and durable.
PV farms impress with their very low electricity generation costs, which are competitive to fossil power plants if avoided CO2-costs are taken into account. PV systems on house and industrial roofs allow for the lowest land consumption and for the local use of solar power, but have slightly higher electricity production costs. So far, they have contributed two-thirds to PV expansion in Germany and are predominantly owned by citizens, giving them the opportunity to help shape the energy transformation.
The use of facades for PV systems, however, has fallen behind. Façade systems are particularly valuable, however, as there is much more space available for them than for roof systems, particularly in the city centres .
If solar energy is combined in an appropriate way with electrical storage systems and heat pumps and if the sectors electricity, mobility and heat are combined, the local use of solar power increases. This reduces the load on distribution networks and contributes decentrally to balancing generation and consumption.
ZSW supports its customers in the analysis of potentials and develops algorithms for the optimised operation of generators, storages and loads, including a suitable charging management for electromobility. The ZSW experts also offer consulting on the development and testing of appropriate algorithms and devices.
As part of the research project "Facade-integrated photovoltaic systems", the ZSW is investigating, among other things, the properties of building-integrated photovoltaics (BIPV) in comparison to PV roof systems. This applies in particular to CIGS façade systems (with thin-film solar modules based on copper, indium, gallium and selenium, or CIGS for short).
A limiting factor for the use of PV roof systems on industrial and administrative buildings is the competition with building services equipment such as heat exchangers, ventilation systems or solar thermal collectors, which fragment the roof surface as shadow-throwing elements.
In addition, however, there may also be a competing use as a walk-in roof garden or for a locally required roof greening. Often, especially on production buildings, it is not possible to realise a PV roof system because the permissible area load is exceeded. In addition, as the number of storeys increases, the share of the PV roof system in electricity generation decreases, as the energy generated is distributed over more and more storeys.
This is why photovoltaics offers a number of advantages in façades: Due to the orientation of the PV systems, energy production is stabilized. The midday peak typical for PV roof systems is eliminated and the share of own consumption increases, also in the morning and evening hours as well as in the winter half-year. A façade system is therefore both grid-compatible and advantageous for the user. In addition, the PV façade system grows with the height of the building.
Decentralised storage systems allow local users to achieve both financial and intangible added value by increasing their own consumption, and also benefit the grid operators by contributing to grid integration of solar power. To achieve this goal, ZSW investigates optimised storage operation and characterises the functioning, service life and safety of storage systems and battery cells.
Further information on the technical properties of PV storage systems is available under the following topics: