illustration: M+W Group

M+W Group and project partners have presented the first results from extensive research into the benefits of combining the use of solar thermal and photovoltaic power plants.

The THERMVOLT study, produced by a partnership of M+W Group, the DLR Institutes for Solar Research and Technical Thermodynamics, the Lappeenranta University of Technology (Finland), and Fichtner GmbH & Co KG focused on the efficiency of solar technologies and the security of power supply.

The THERMVOLT Project was an engineering, economic and environmental comparison of solarthermal (CSP) and photovoltaic (PV) power plants with a battery storage facility. The research examined how these power plants could be developed to generate electricity from solar energy that is affordable, environmentally friendly as well as available around the clock.

The CSP power plants investigated had a thermal energy storage facility combined with a fossil fuel burner which was used as necessary and linked to specific emissions limits. The PV combined power plants had a battery storage facility and a fossil reserve system (for example a gas-fired power plant) with which they could be operated in a network.

Manfred Engelhard, Technology Manager Energy at M+W Group, explains, “The key challenge for achieving an increasing proportion of renewably generated electricity in the grid is related to the availability of effective and affordable storage solutions. After all, the sun does not shine all the time and the fluctuation of 'feed-in' therefore rises as the proportion of solar energy increases in the grid. Electricity storage systems in the form of large, stationary battery storage banks along with PV systems demonstrate a high potential for reducing costs. The combination of PV and batteries is likely to make an important contribution to certainty of supply through the delivery of predictable electricity at an attractive price.”

The results of the study indicate that currently a combination of CSP and PV is more cost-effective in most scenarios than the use of only one of the two technologies. The photovoltaic section of the power plant supplies electricity directly to the grid during the day, while the solar thermal section stores solar energy in a thermal storage facility. This provides the capability to feed this energy into the grid as electricity during the night.

On account of the current high level of costs for battery storage, PV-battery combined power plants are currently subject to the highest electricity generation costs. However, these costs are likely to approximate to the electricity generation costs of solar thermal power plants with thermal storage under favourable conditions by the year 2030, or may even fall below this level of expenditure.

Tags: M+W Group