Two-positional tracking for a stand-alone PV-module (or solar thermal collector) is always profitable in terms of produced energy. A solar farm in the regime of the two-positional tracking always produces more energy than a fixed one, considering the area of the modules. While considering the area of installation, two-positional tracking may be problematic, while the density of the modules cannot be high. At high latitudes, two-positional tracking is preferred for highly tilted modules, especially for facade farms. If the economy of the capital cost of the PV-modules is preferred, the two-positional exposure of these may be recommended. If the facade of a dwelling should be utilized highly, the PV-modules should be installed traditionally on the wall. Naturally, architectural recommendations should be considered.

• A solar PV-farm that uses the two-positional tracking of modules about their axes is effective if the distance between the axes is larger than the two-three widths of the modules concerned.

• The estimated average gain of a vertical solar PV-farm with the two-positional tracking is 10-20% compared with the fixed one and depends on the relative distance between the modules and their deflection angle.

• The average gain of a solar PV-farm with the two-positional tracking is 5-10% less than that of a stand-alone PV-module at the same deflection angle.

Acknowledgement

The author thanks the Estonian Science Foundation for their support, grant 6563.

References

[1] Teolan Tomson, Discrete two-positional tracking of solar collectors, Renewable Energy, 33 (2008) 3, 400-405.

[2] D. Weinstock, J. Appelbaum, Optimal Solar Field Design of stationary Collectors, Transactions of the ASME, vol. 126 (2008) 898-905.

[3] D. Weinstock, J. Appelbaum, Optimization of Economic Solar Field Design of Stationary Thermal Collectors. Journal of Solar Energy Engineering, vol. 129 (2007) 363-370.

[4] Russak, V., Kallis, A., (2003). Handbook of Estonian Solar Radiation Climate, Ed. by H. Tooming,

EMHI, Tallinn.

[5] Solar Energy. The state of the art, (2001). Ed by J. Gordon, James & James, London, p. 194.

[6] Duffie, J. A. and Beckman, W. A., Solar Engineering of Thermal Processes, (2006), J. Wiley & Sons INC, Hoboken, NJ, USA.