Make capacity growth parameters optional

docs/inputs/technodata.rst

@@ -81,7 +81,7 @@ var_par, var_exp
 
    ProductionRef is the production of a reference capacity (CapRef) for the cost estimate decided by the modeller before filling the input data files.
 
-Growith constraints
+Growith constraints (optional)
    MaxCapacityAddition
       represents the maximum addition of installed capacity per technology, per year in a period, per region.
 
@@ -107,6 +107,8 @@ Growith constraints
    Growth constraints are applied for each single agent in a multi-agent simulation. When only one agent is present, the growth constraints
    apply individually to the "New" and "Retrofit" agent, when present.
 
+   If any of the three parameters are not provided in the technodata file, that particular constraint is not applied.
+
 
 TechnicalLife
    represents the number of years that a technology operates before it is decommissioned.

src/muse/constraints.py

@@ -275,7 +275,7 @@ def max_capacity_expansion(
     search_space: xr.DataArray,
     technologies: xr.Dataset,
     **kwargs,
-) -> Constraint:
+) -> Constraint | None:
     r"""Max-capacity addition, max-capacity growth, and capacity limits constraints.
 
     Limits by how much the capacity of each technology owned by an agent can grow in
@@ -310,7 +310,22 @@ def max_capacity_expansion(
         .. math::
 
             \Gamma_t^{r, i} \geq 0
+
+    :math:`L_t^r(y)`, :math:`G_t^r(y)` and :math:`W_t^r(y)` default to np.inf if
+    not provided (i.e. no constraint).
+    If all three parameters are not provided, no constraint is applied (returns None).
     """
+    # If all three parameters are missing, don't apply the constraint
+    if not any(
+        param in technologies
+        for param in (
+            "max_capacity_addition",
+            "total_capacity_limit",
+            "max_capacity_growth",
+        )
+    ):
+        return None
+
     # case with technology and region in asset dimension
     if capacity.region.dims != ():
         names = [u for u in capacity.asset.coords if capacity[u].dims == ("asset",)]
@@ -344,14 +359,14 @@ def max_capacity_expansion(
 
     # Max capacity addition constraint
     time_frame = int(capacity.year[1] - capacity.year[0])
-    add_cap = techs.max_capacity_addition * time_frame
+    add_cap = techs.get("max_capacity_addition", np.inf) * time_frame
 
     # Total capacity limit constraint
-    limit = techs.total_capacity_limit
+    limit = techs.get("total_capacity_limit", np.inf)
     total_cap = (limit - forecasted).clip(min=0)
 
     # Max capacity growth constraint
-    max_growth = techs.max_capacity_growth
+    max_growth = techs.get("max_capacity_growth", np.inf)
     growth_cap = initial * (max_growth + 1) ** time_frame - forecasted
 
     # Relax growth constraint if no existing capacity

tests/test_constraints.py

@@ -481,6 +481,24 @@ def test_max_capacity_expansion(max_capacity_expansion):
     ).all()
 
 
+def test_max_capacity_expansion_no_limits(
+    market_demand, capacity, search_space, technologies
+):
+    from muse.constraints import max_capacity_expansion
+
+    # Without growth limits, the constraint should return None
+    techs = technologies.drop_vars(
+        ["max_capacity_addition", "max_capacity_growth", "total_capacity_limit"]
+    )
+    result = max_capacity_expansion(
+        market_demand,
+        capacity,
+        search_space,
+        techs,
+    )
+    assert result is None
+
+
 def test_max_production(max_production):
     dims = {"replacement", "asset", "commodity", "timeslice"}
     assert set(max_production.capacity.dims) == dims