A solar power system represents a worthwhile investment and is comparable to a long-term capital investment with annual interest payments. The returns gained from the invested equity are generally considerably higher than if the money were invested in a savings account. If the solar power system has been professionally designed and high quality components used, the economic feasibility of the solar power system can be accurately forecast.

The more favourable the position of the solar modules and the simpler the installation, the greater the returns. On behalf of its project partners, Soltecture offers to find an efficient solution and to optimise the profitability of the solar power system. By way of example, the calculation on this page shows how the annual yield, funding structures and ongoing costs for the system enable the returns on the investment to be evaluated.

Annual yield

The energy produced by a solar power system depends on the location, its orientation and the solar technology used. Since the solar irradiance deviates by only around ± 10% and there is historic climate data available, this enables the average solar irradiance for a given location to be accurately forecast. Based on the key technical data for the solar power system, the energy yield can then be calculated in kilowatt hours (kWh) per installed rated output (Wp) and year (a) (kWh/kWp·a). The revenue gained for operating the system is therefore the product of the energy yield and the feed-in tariff for solar electricity.

Soltecture offers its project partners system-specific yield forecasts, whereby it utilises the experience gained from operating numerous systems across many years. In addition, it is also possible to obtain independent reports from expert appraisers.


Large-scale solar power systems are generally funded by a combination of the operator’s own capital and long-term external financing (loans). A ratio of 20% equity and 80% external financing is typical. The interest rates are taken into account in costing the solar power system. Based on the internal rate of return on the equity invested it is possible to calculate the profitability of the solar power system. Soltecture works together with selected banks that finance solar power systems with Soltecture modules and is therefore able to provide its project customers with help in funding solar power systems.

Ongoing costs

Solar power systems require little maintenance. Since there are no moving parts, it is essentially only the electrical functions that have to be monitored. If there is a loss of yield, the solar power system must be serviced by a specialist company. At locations with considerable air pollution or dust, the modules should also be cleaned occasionally - in Germany this is not normally necessary with solar power systems at 30° inclinations. When calculating the profitability, servicing costs are normally taken into account with a low fixed annual sum. If desired, Soltecture will also look after the system monitoring, enabling it to respond quickly in the event of yield losses.


You can download a PDF document with an example calculation of the profitability here.