enable usage of Highs solver

flexmeasures/data/models/planning/linear_optimization.py

@@ -339,9 +339,16 @@ def cost_function(m):
     model.costs = Objective(rule=cost_function, sense=minimize)
 
     # Solve
-    results = SolverFactory(current_app.config.get("FLEXMEASURES_LP_SOLVER")).solve(
-        model
-    )
+    solver_name = current_app.config.get("FLEXMEASURES_LP_SOLVER")
+    opt = SolverFactory(solver_name)
+
+    if "highs" in solver_name.lower():
+        try:
+            results = opt.solve(model)
+        except RuntimeError:
+            results = opt.solve(model, load_solutions=False)
+    else:
+        results = opt.solve(model)
 
     planned_costs = value(model.costs)
     planned_power_per_device = []