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Effect of tilt and orientation on Solar and PV energy systems
8. Orientation and Tilt Dependence of a Fixed PV Array Energy Yield Based on Measurements of Solar Energy and Ground Albedo – a Case Study of Slovenia
By Jože Rakovec, Klemen Zakšek, Kristijan Brecl, Damijana Kastelec and Marko Topic, Submitted: October 27th 2010Reviewed: April 6th 2011Published: August 1st 2011 DOI: 10.5772/18386 
- Considering only direct solar irradiation, the optimal tilt angle during the year can be calculated as φ - δs, where δs is the declination of the Sun.
- Joule losses in wirings of PV modules into PV arrays and inverter losses account to losses in output power of PV system.
- Long-term measured meteorological values should be used to obtain reliable results on PV yield
- Measured irradiation values are the most important parameter in photovoltaics,
- The albedo changes significant during winters only as the ground covered by snow is often even brighter than the sky.