double solar rooftop PV potentials (closes PyPSA#935)

# Conflicts:
#	doc/release_notes.rst

doc/release_notes.rst

@@ -10,6 +10,82 @@ Release Notes
 Upcoming Release
 ================
 
+* Doubled solar rooftop potentials to roughly 1 TW for Europe based on `recent
+  European Commission reports
+  <https://www.epj-pv.org/articles/epjpv/full_html/2024/01/pv230071/pv230071.html>`_.
+
+* Remove exogenously set share of rooftop PV (``costs: rooftop_share:``).
+  Rooftop and utility-scale PV are now largely handled as separate technologies
+  with endogenous shares.
+
+* New technology, solar PV with single-axis horizontal tracking (on a N-S axis),
+  with a carrier called ``solar-hsat`` to the networks. The default option for adding
+  this technology is set to ``true`` in the ``config.yaml``.
+
+* The technology-data version was updated to v0.9.0.
+
+* Bugfix to avoid duplicated offshore regions.
+
+* Added option ``industry: HVC_environment_sequestration_fraction:`` to specify
+  the fraction of carbon contained plastics that is permanently sequestered in
+  landfill. The default assumption is that all carbon contained in plastics is
+  eventually released to the atmosphere.
+
+* Added option for building waste-to-energy plants with and without carbon
+  capture to consume non-recycled and non-sequestered plastics. The config
+  settings are ``industry: waste_to_energy:`` and ``industry:
+  waste_to_energy_cc``. This does not include municipal solid waste.
+
+* Bump minimum ``powerplantmatching`` version to v0.5.15.
+
+* Add floating wind technology for water depths below 60m
+
+* Add config ``run: shared_resources: exclude:`` to specify additional files
+  that should be excluded from shared resources with the setting ``run:
+  shared_resources: base``. The function ``_helpers/get_run_path()`` now takes
+  an additional keyword argument ``exclude_from_shared`` with a list of files
+  that should not be shared. This keyword argument accepts a list of strings
+  where the string only needs to match the start of a filename (e.g.
+  ``"transport_data"`` would exclude both ``transport_data.csv`` and
+  ``transport_data_{simpl}_{clusters}.csv`` from being shared across scenarios.
+
+* Move switch ``run: shared_resources:`` to ``run: shared_resources: policy:``.
+
+* Add config land_transport_demand_factor to model growth in land transport demand for different time horizons.
+
+* Allow dictionary for the config aviation_demand_factor.
+
+* Add option to post-discretize line and link capacities based on unit sizes and
+  rounding thresholds specified in the configuration under ``solving: options:
+  post_discretization:`` when iterative solving is enables (``solving: optiosn:
+  skip_iterations: false``). This option is disabled by default.
+
+* Group existing capacities to the earlier grouping_year for consistency with optimized capacities.
+
+* Update data bundle:
+
+  - Merge electricity-only and sector-coupled data bundles into `one bundle
+    <https://zenodo.org/records/10973944>`_. This means that the rule
+    ``retrieve_sector_databundle`` was removed.
+
+  - Include rasterised ``natura.tiff`` in data bundle and remove rule
+    ``retrieve_natura_raster``.
+
+  - Remove rule ``build_natura_raster`` as this rule is rarely run and increases
+    the data bundle size considerably.
+
+  - Remove outdated files from data bundle (e.g., Eurostat energy balances)
+
+  - Reduce spatial scope of GEBCO bathymetry data to Europe to save space.
+
+  - Remove the use of a separate data bundle for tutorials.
+
+  - Directly download `Hotmaps Industrial Database
+    <https://gitlab.com/hotmaps/industrial_sites/industrial_sites_Industrial_Database/-/blob/master/data/Industrial_Database.csv>`__
+    from source and remove ``Industrial_Database.csv`` from data bundle.
+
+* bugfix: installed heating capacities were 5% lower than existing heating capacities
+
 * Include gas and oil fields and saline aquifers in estimation of CO2 sequestration potential.
 
 * bugfix: convert Strings to pathlib.Path objects as input to ConfigSettings

scripts/prepare_sector_network.py

@@ -1027,9 +1027,9 @@ def insert_electricity_distribution_grid(n, costs):
     else:
         pop_solar = pop_layout.total.rename(index=lambda x: x + " solar")
 
-    # add max solar rooftop potential assuming 0.1 kW/m2 and 10 m2/person,
-    # i.e. 1 kW/person (population data is in thousands of people) so we get MW
-    potential = 0.1 * 10 * pop_solar
+    # add max solar rooftop potential assuming 0.1 kW/m2 and 20 m2/person,
+    # i.e. 2 kW/person (population data is in thousands of people) so we get MW
+    potential = 0.1 * 20 * pop_solar
 
     n.madd(
         "Generator",