PVGIS web site offers data and tools for geographical assessment of solar photovoltaics. New features have been put online that include heating degree days, probability distribution of global irradiation, assessments of 2-axis tracking PV systems and display of the horizon outline for any location in Europe, Africa and South West Asia. PVGIS communicates in 6 languages now, French and Spanish being currently implemented. [Original announcement here]

Here is an example of what you can do with the PVIS web site, entering data for Asse, Belgium:

Location: 50°54'45" North, 4°6'7" East, Elevation: 71 m a.s.l,
Nearest city: Asse, Belgium (0 km away)
Optimal inclination angle is: 34 degrees
Annual irradiation deficit due to shadowing (horizontal): 0.0 %

Month	Irradiation at inclination: (Wh/m2/day) 0 deg.
Jan	637
Feb	1385
Mar	2161
Apr	3537
May	4541
Jun	4678
Jul	4870
Aug	4111
Sep	2762
Oct	1673
Nov	860
Dec	494
Year	2649