Issue1451 add pvt model

[Philipp-Schmitz]

added a simple photovoltaic thermal collector based on the already existing solar thermal model

[FWuellhorst]

Thanks for this addition to the AixLib.

The equation look correct, but there are some style-guide issues which need to be addressed. If you have questions, just comment below. Most of them were already wrong in the SolarThermal model, but we agreed on fixing those issues if we adapt existing models.

[ebc-aixlib-bot]

Thank you for making a Pull Request to AixLib!

Our CI pipeline will help you finalize your contribution.
Here's what is typically checked:

• HTML syntax of your models, primarily in your documentation.
• Adherence to the naming convention in all changed files.
• Ability to check all models.
• Ability to simulate all models, if they are examples.
• If your contribution changes existing reference results.

If HTML errors occur, I will fix the issues using a separate pull request.
For the other checks, I will post the results here: https://rwth-ebc.github.io/AixLib/issue1451-add-pvt-model/index.html

Tips to fix possible naming violations:

• Stick to the naming guidelines, e.g. Namespace Requirements
• Do all paramaters, variables, models, etc. have a description?
• Use absolute paths to classes! -> AixLib.Fluid.HeatExchangers.Radiator - Avoid: HeatExchangers.Radiator

If all CI stages pass and you have addressed possible naming violations, please consider the following:

• Use "group" and "tab" annotations to achieve a good visualization window.
• Use units consistently.
• Instantiate the replaceable medium package as:
  replaceable package Medium = Modelica.Media.Interfaces.PartialMedium "Medium model";
  instead of using a full media model like AixLib.Media.Water directly.
• Never using absolute paths to files (e.g., C: or D:). Replace them with modelica://AixLib/....
• Ensure your documentation is helpful and concise.
• Make sure icons are clear. Please avoid using images!
• Stick to 80 characters per line, as long as it makes sense.
• Add or modify examples for new or revised models.
• Include a simulate-and-plot script as a regression test for new models.
  How? Follow the documentation here: https://github.com/ibpsa/modelica-ibpsa/wiki/Unit-Tests#how-to-include-models-as-part-of-the-unit-tests
  Tip: To create the initial script, you can use Dymolas script generator, explained here: https://www.claytex.com/tech-blog/how-to-use-a-plot-script/)

Once you have addressed these points, you can assign a reviewer.
Although this process may seem tedious, ensuring CI passes allows the reviewer to focus
their time on the actual modeling rather than syntax and unintended breakages caused by your changes.

If you have any questions or issues, please tag a library developer.
Once again, thank you for your valuable contribution!

[ebc-aixlib-bot]

Reference results have been displayed graphically and are created under the following page https://rwth-ebc.github.io/AixLib/issue1451-add-pvt-model/charts

[ebc-aixlib-bot]

Reference results have been displayed graphically and are created under the following page https://rwth-ebc.github.io/AixLib/issue1451-add-pvt-model/charts

[ebc-aixlib-bot]

Errors in regression test. Compare the results on the following page\n https://rwth-ebc.github.io/AixLib/issue1451-add-pvt-model/charts

[ebc-aixlib-bot]

Errors in regression test. Compare the results on the following page\n https://rwth-ebc.github.io/AixLib/issue1451-add-pvt-model/charts

[TobiasSpratte]

Looks nice, thank you for the pvt model!

[TobiasSpratte]

maybe change the description in the EN12975 model from "performance data" to something like "performance data for Solar Thermal Collector". This could be helpful to understand that per is only for the thermal part and perPVT is both, thermal and electric.

[FWuellhorst]

I used "Performance data for both solar thermal collector and PV", is this better?