Pick the one path that matches your charging reality.
Path A — Reliable home charging
Model most charging at your actual residential tariff, then add a smaller public-fast-charging share. Include charger installation and any electrical-upgrade cost.
Path B — Mixed home and public charging
Use a weighted electricity price: home kWh × home share plus public kWh × public share. Stress-test the result if the public-charging share grows.
Path C — Mostly public charging
Use your real nearby network prices and detour/time costs. Do not use a low home tariff if you cannot realistically charge at home.
Path D — Incentive-dependent purchase
Run two cases: incentive received and incentive not received or delayed. A purchase should not look affordable only because an unapproved subsidy was assumed.