Fix/feedin tariff alternative

[smartie2076]

Fix #610

Changes proposed in this pull request:

• set feed-in tariff to negative when executing C0.define_sink in C0.define_dso_sinks_and_sources
• ❌ No adaptation of C1.check_feedin_tariff() necessary
• added benchmark test for feed-in tariff
• make sure that feedin revenue is indeed substracted from the operational costs
• ❌ give a hint in readthedocs about feed-in tariff sign --> looks fine in rtd: "Price received for feeding electricity into the grid." implies that it's positive.

The following steps were realized, as well (if applies):

• Use in-line comments to explain your code
• Write docstrings to your code (example docstring)
• For new functionalities: Explain in readthedocs
• Write test(s) for your new patch of code (pytests, assertion debug messages)
• Update the CHANGELOG.md
• Apply black (black . --exclude docs/)
• Check if benchmark tests pass locally (EXECUTE_TESTS_ON=master pytest)

Please mark above checkboxes as following:

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• Done

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[smartie2076]

@SabineHaas this PR can now be reviewed. I also added a lot of pytests, but if you review commit by commit everything should be clear.

[smartie2076]

I have not checked the investments and if the costs add up. Especially for the pie charts, the revenues from feedin might result in weird stuff. I would say though that we do that in a new PR, eg. when merging #613?

[SabineHaas]

Thank you for reworking @smartie2076. Unfortunately I still get the error mentioned in #670. Apart from that, two more benchmark tests fail now when I run EXECUTE_TESTS_ON=master pytest locally, see error log:
pytest_master_log.txt

Could you please run the test locally again and check?

[smartie2076]

Thank you for reworking @smartie2076. Unfortunately I still get the error mentioned in #670. Apart from that, two more benchmark tests fail now when I run EXECUTE_TESTS_ON=master pytest locally, see error log:
pytest_master_log.txt

Could you please run the test locally again and check?

So weird, when I ran them Friday they seemed to pass... will check what this is about.

[SabineHaas]

Thank you for reworking @smartie2076. Unfortunately I still get the error mentioned in #670. Apart from that, two more benchmark tests fail now when I run EXECUTE_TESTS_ON=master pytest locally, see error log:
pytest_master_log.txt
Could you please run the test locally again and check?

So weird, when I ran them Friday they seemed to pass... will check what this is about.

Thank you so much!

[smartie2076]

@SabineHaas fixed the pytests. Go commit by commit, because somehow the files that were changed in another PR actually appear in this one now...

[smartie2076]

@SabineHaas ready to be merged!

If there is still something wrong, I am really at a loss here, as my pytests run trough:=========================================================== 319 passed, 2 skipped, 14 warnings in 529.66s (0:08:49) ============================================================

[SabineHaas]

@SabineHaas ready to be merged!

If there is still something wrong, I am really at a loss here, as my pytests run trough:=========================================================== 319 passed, 2 skipped, 14 warnings in 529.66s (0:08:49) ============================================================

:D
I've checked it, it's fine 👍