fix(mpc): give Energyplan 1.5 s when a car is plugged in

.changeset/energyplan-ev-budget.md

@@ -0,0 +1,5 @@
+---
+"ftw": patch
+---
+
+Give the Energyplan planner 1.5 s instead of 0.5 s when a car is plugged in. On a Raspberry Pi 4, 0.5 s stopped just before the planner could improve on its first plan for the car, and the published plan could cost about 11% more than the best one. Battery-only plans keep their 0.5 s budget, and the first slot's remaining time still caps every budget.

go/internal/mpc/energyplan.go

@@ -28,6 +28,10 @@ func NewEnergyplanOptimizer(binary string) (*EnergyplanOptimizer, error) {
 
 const (
 	energyplanSmallBudget = 500 * time.Millisecond
+	// With a car plugged in, a Raspberry Pi 4 needs about 0.6-0.7 s before
+	// the planner can improve on its first plan; at 0.5 s it stopped just
+	// short and published plans about 11% above the proven optimum.
+	energyplanEVBudget    = 1500 * time.Millisecond
 	energyplanFleetBudget = 5 * time.Second
 	// Leave time for ValidatePlan and publication before firstSlotExpired.
 	energyplanPublishMargin = 50 * time.Millisecond
@@ -42,6 +46,9 @@ func energyplanTimeBudget(slots []Slot, p Params) time.Duration {
 	// Core already adjusts PV to one downside horizon. That margin does not
 	// add worker scenarios or change this model's size.
 	budget := energyplanSmallBudget
+	if len(p.activeLoadpoints()) > 0 {
+		budget = energyplanEVBudget
+	}
 	// 1 battery + 1 EV is 5 "assets". A 193-slot villa with demand charges
 	// routes to fleet MILP; 193*6 would leave it on the 500 ms budget.
 	if len(slots)*assets >= 193*5 || p.PVCurtailment.MinW > 0 || len(p.DemandCharges) > 0 {

go/internal/mpc/energyplan_test.go

@@ -309,8 +309,8 @@ func TestBatterylessEVBudgetDoesNotInventStorage(t *testing.T) {
 	for i := range horizon {
 		horizon[i] = slots[0]
 	}
-	if got := energyplanTimeBudget(horizon, p); got != 500*time.Millisecond {
-		t.Fatalf("batteryless EV budget=%v", got)
+	if got := energyplanTimeBudget(horizon, p); got != energyplanEVBudget {
+		t.Fatalf("batteryless EV budget=%v, want %v", got, energyplanEVBudget)
 	}
 	p.CapacityWh = 20000
 	if got := energyplanTimeBudget(horizon, p); got != 5*time.Second {
@@ -488,3 +488,25 @@ func TestEnergyplanLateFleetReplanDoesNotStartDoomedSolve(t *testing.T) {
 		t.Fatalf("wanted previous plan, got %+v", plan)
 	}
 }
+
+// A car on a short published-price horizon gets more time than a battery
+// alone. A Pi 4 at 0.5 s stopped just before the planner could improve on
+// its first plan for the car.
+func TestEVGetsLongerBudgetThanBatteryAlone(t *testing.T) {
+	slots, p := topologyFixture(1, 1)
+	horizon := make([]Slot, 112)
+	for i := range horizon {
+		horizon[i] = slots[0]
+	}
+	if got := energyplanTimeBudget(horizon, p); got != energyplanEVBudget {
+		t.Fatalf("1b+1EV 112-slot budget=%v, want %v", got, energyplanEVBudget)
+	}
+	battery, pb := topologyFixture(1, 0)
+	short := make([]Slot, 112)
+	for i := range short {
+		short[i] = battery[0]
+	}
+	if got := energyplanTimeBudget(short, pb); got != energyplanSmallBudget {
+		t.Fatalf("battery-only 112-slot budget=%v, want %v", got, energyplanSmallBudget)
+	}
+}