The assessment of thermal solar systems based on economic aspects is difficult, since the cost effectiveness of this type of systems strongly depends on the development of the fossil fuel prices.

An additional aspect complicating an economic assessment is that the advanced storage technologies are not introduced to the market up to now. But only when a technology is established on the marked and is produced in large quantities the results of an economic analysis are reliable /2/.

Due to this the following cost considerations are limited to system concepts that can be realised with today’s system technology and with the use of water as heat storage medium.

Table 1 shows the solar heat prices for various collector areas and collector types as well as for different store volumes. For each configuration an average and an inexpensive value are given. The average value is determined without taking into account subsidies or self services (e. g. installation by the owner). For the calculation of the inexpensive value these possibilities for saving were taken into account. Additionally discount prices of the components were used.