If you are a renewable energy fanatic like me, a solar energy enthusiast, or a engineer trying to get quick rough estimtaes for a system you are designing, then you will almost always need to use some software. In the following list, I have compiled 8 FREE software and online design tools for on-grid and off-grid solar systems design.
1. PVWatts: https://pvwatts.nrel.gov
PVWatts (developed by the National Renewable Energy Laboratory NREL) is a great and easy-to-use online tool for estimating the energy yield of grid-connected PV systems anywhere in the world. I would rate it as no.1 in this list for beginners.
2. SAM: https://sam.nrel.gov
SAM (or System Adviser Model) is another software developed by NREL and is probably the most complex in this list. SAM is used to model the technical performance of several renewable energy system and evaluate economic and financial feasibility. The economic and financial models in SAM are one of the most distinguising features that facilitate the decision making and project management process. Hence, using SAM ideally requires sound knowledge of the economics of renewable energy projects and financial models. SAM receives regular software updates and is great to use for university research projects.
3. REopt Lite: https://reopt.nrel.gov/tool
REopt Lite is another online tool by NREL that is used to optimize grid-connected hybrid PV systems with storage from an economic viewpoint. It can also be used for component sizing and cost reduction.
4. SISIFO: https://www.sisifo.info/en/default
SISIFO is an online design tool developed by the Solar Energy Institute of the Universidad Politecnica de Madrid and is used for the simulation of on-grid PV systems and also irrigation systems powered by PV panels.
5. Global Solar Atlas: http://globalsolaratlas.info
The Global Solar Atlas is one of my favorite tools in this list! This atlas, which is a World Bank funded project, contains solar resources and wind resources data for the entire globe and can be used for quick estimations of system yields.
6. PVGIS: https://re.jrc.ec.europa.eu/pvgis.html
PVGIS is a web-based tool designed at the European Commission Joint Research Centre and can be used for evaluating the performance of on-grid and off-grid PV systems globally.
7. PV*SOL online: http://pvsol-online.valentin-software.com/#/
PV*SOL online, developed by Valentin Software, is a web version of the famous PV*SOL software and is used for the design and simulation of PV systems.
8. Calculationsolar: http://calculationsolar.com/index.php
Calculationsolar.com is a simple online calculator for designing PV systems based on user-input load data.