Compare results at `openpv` with other simulation tools

[FlorianK13]

This is also some sort of calibration task. It would need to:

• find relevant other solar simulation tools
• Define comparable attributes for each simulation tool, such as:
  • open source?
  • free vs paid?
  • includes shading?
  • Includes simulation of time series?
• compare annual electricity production of openpv with the simulated results from other tools

[stheid]

We have chatted already, but for completeness of the issue:

PVGIS is definitely among the most important ones

• free, not open-source
• includes shading (via custom horizons, automatic horizons only include elavation afaik)
• can make predictions on hourly level, so it can be combined with time series data.