Calculator and relationship between slope, pitch, gradient, rise, run length and tilted length of a roof or solar photovoltaic panels

Free online calculator of the slope according to measurement of a roof or solar

Solar Water Heating Calculation for built up system.
Note to Users: California F-Chart has been designed to calculate solar thermal water heating contributions for built up solar systems.

PVWatts is a useful map-based free online software for US and international photovoltaic sites analysis.
It could give the global annual energy output of PV systems connected to the grid in USA or in many part of the world. For many

Get worlwide climate data for free from NASA in 3 steps ?

Software dedicated to large hot water systems as hotels, industry, camping...

NO MORE AVAILABLE! It has been replaced by TRANSOL, see on Professional solar thermal

SHW is a simulation software for Thermal Solar Systems. It is a freeware for Research and Teaching use.
Designed from unit of Energy Efficient Buildings at the University of Innsbruck, Austria.
No Online help is

Opensolar is a free online solar design tool.

Just create a free account to start to use it.

With OPEN SOLAR you can create build-ready quick proposals using OpenSolar's class-leading 3D design technology:
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This section provide a list of free solar thermal softwares.

With Easy-PV you can easily create a PV project online for free. You can create an instant schematic and use the performance calculator to estimate PV system output. Easy-PV was designed and built by the folks at Midsummer Solar Wholesale.

SISIFO is an online, free-software, simulator of PV systems developed by the IES-UPM in the frame of the European project PVCROPS.
This version of SISIFO allows the simulation of different types of grid-connected PV systems, such as large

PVGIS is an online free solar photovoltaic energy calculator for stand alone or connected to the grid PV systems and plants, in Europe, Africa, America and Asia. Solar electricity generator simulation and solar