Properly handle reserve_shortfall when variable not present.

src/solution/solution.jl

@@ -51,7 +51,9 @@ function solution(model::JuMP.Model)::OrderedDict
     sol["Switch on"] = timeseries(model[:switch_on], instance.units)
     sol["Switch off"] = timeseries(model[:switch_off], instance.units)
     sol["Reserve (MW)"] = timeseries(model[:reserve], instance.units)
-    sol["Reserve shortfall (MW)"] = model[:reserve_shortfall]
+    sol["Reserve shortfall (MW)"] = (model[:instance].shortfall_penalty[t] >= 0) ?
+            model[:reserve_shortfall] :
+            [0 for t in 1:T]
     sol["Net injection (MW)"] =
         timeseries(model[:net_injection], instance.buses)
     sol["Load curtail (MW)"] = timeseries(model[:curtail], instance.buses)

src/validation/validate.jl

@@ -324,7 +324,9 @@ function _validate_reserve_and_demand(instance, solution, tol = 0.01)
         # Verify spinning reserves
         reserve =
             sum(solution["Reserve (MW)"][g.name][t] for g in instance.units)
-        reserve_shortfall = solution["Reserve shortfall (MW)"][t]
+        reserve_shortfall = (instance.shortfall_penalty[t] >= 0) ?
+            solution["Reserve shortfall (MW)"][t] : 0
+
         if reserve + reserve_shortfall < instance.reserves.spinning[t] - tol
             @error @sprintf(
                 "Insufficient spinning reserves at time %d (%.2f + %.2f should be %.2f)",