PVWatts calculator determines the energy production and cost savings of grid-connected photovoltaic (PV) energy systems throughout the world.
Solar Calculator, Great Circle Studio. Information regarding solar altitude and azimuth for every date and location. Interesting factoid with relevance to photovoltaic systems: in temperate zones, for several weeks before and after the summer solstice, the sun (the "apparent solar azimuth") may move 45 degrees or more in one hour in the middle of the day.
