Resources

Weather and solar resource data

• European Union - Photovoltaic Geographical Information System A free and very detailed production modeling, system design tool and source for weather data that works in most locations globally. Also available in Spanish, French, and Italian.

• World Bank - Global Solar Atlas A detailed global irradiance and meteorological data source. Also includes a free production modeling tool. Only available in English.

• - ASHRAE Climatic Design Conditions 2009/2013/2017 A detailed database of long-term real world data from weather stations around the world analyzed and provided by ASHRAE.

• NASA - Power Data Viewer A detailed global irradiance and meteorological data source provided by the National Aeronautics and Space Administration (NASA) that provides data globally. It is capable of exporting data sets and creating unique maps. Only available in English.

• National Renewable Energy Laboratories - PVWatts Calculator A free production modeling and system design tool from the National Renewable Energy Labs (NREL) that works in many areas around the world. Only available in English.

• National Renewable Energies Laboratories - National Solar Resource Database An interactive map with downloadable solar resource and weather data sets for the Americas and South Asia.

Wiring

• Calculator.net - Voltage drop calculator A simple voltage drop calculator that can be used to quickly determine the percentage of voltage drop for a particular circuit with basic information.

• Smartgauge.co.uk - Battery bank configurations An excellent article on voltage drop and battery wiring with simple diagrams showing good and bad wiring practices for various different battery bank configurations.

System efficiency

• Do the Math - Blow-by-Blow PV System Efficiency: A Case Study for Storage An examination of round-trip efficiency of an off-grid PV system.