With v0.3, the API of the GenericStorage has changed. Due to the open structure of solph, the old parameter names were still accepted, but practically ignored. Therefore users may not notice that a default value is used instead of the value they wanted. Especially after an update from v0.2.x to v0.3.0, code often still runs but produces different results. With the new v0.3.1 release, an error is raised when legacy parameter names are used. We work on a structure to avoid such problems in the future. To update, just:
pip install oemof --upgrade