Class "Gef", directly.
Class "G0", by class "Gef", distance 2.
Class "Meteo", by class "Gef", distance 3.
Class "Sol", by class "Gef", distance 3.
References
Perpiñán, O, Energía Solar Fotovoltaica, 2012.
(http://procomun.wordpress.com/documentos/libroesf/)
Perpiñán, O. (2012), "solaR: Solar Radiation and Photovoltaic
Systems with R", Journal of Statistical Software, 50(9), 1-32,http://www.jstatsoft.org/v50/i09/