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Your EV has a battery 4-8x larger than a typical home backup battery. A Tesla Model Y has 75-81 kWh usable; a Tesla Powerwall has 13.5 kWh. With a bidirectional charger and a V2H-compatible EV, your car can power your home for 2-5 days during an outage — far longer than any home battery. This calculator shows exactly how long your specific EV + home load combination will last.
V2H (Vehicle-to-Home) and V2G (Vehicle-to-Grid) are finally going mainstream in 2025-2026. Compatible EVs include the Ford F-150 Lightning, Chevrolet Silverado EV, Hyundai Ioniq 5/6, Kia EV6/EV9, Nissan Leaf (CHaDeMO bidirectional), and Tesla Model 3/Y (with the new Powershare update). You'll need a bidirectional home charger ($4,000-6,000 installed) — but that's still cheaper than a single Powerwall and gives you 5-10x the runtime.
This is especially valuable in South Africa (loadshedding), Australia (storm outages), and US regions prone to hurricanes, winter storms, or wildfire PSPS events. Instead of buying a $15,000 generator or a $15,000 battery bank, you can use the battery you already own.
- EV battery capacity — your EV's total battery size. Check the spec sheet. Most modern EVs: 60-100 kWh.
- Usable for V2H — most V2H systems limit discharge to 50-70% to preserve battery health. Ford Lightning allows 80%. Tesla Powershare: ~60%.
- Inverter efficiency — DC battery to AC home power conversion. Bidirectional chargers: 88-93%.
- Backup mode — Essential (500W: fridge, lights, router, freezer) gives longest runtime. Typical (1200W: + TV, microwave, fans) is realistic for most outages. Full (2500W+: + AC, geyser) drains fast.
- Home battery cost — used to calculate the equivalent value of your EV as a backup. $10,000-15,000 is typical for a 13.5 kWh Powerwall install.
V2H requires three things: (1) a V2H-compatible EV, (2) a bidirectional charger (Wallbox Quasar, Ford Charge Station Pro, Fermata FE-15), (3) a transfer switch or home integration kit. Total install: $4,000-6,000.
When to Use This Calculator
Which EVs support V2H today?
As of 2026, the V2H-compatible EV list includes: Ford F-150 Lightning (built-in, 80% usable), Chevy Silverado EV (built-in), Hyundai Ioniq 5/6 (with V2L adapter for lower-power loads), Kia EV6/EV9 (V2L), Nissan Leaf (CHaDeMO bidirectional via Wallbox Quasar), Tesla Model 3/Y (2024+ with Powershare update and Wall Connector). Coming soon: Rivian R1T/R1S, GM Ultium platform EVs. If you don't have one of these, V2H isn't an option yet.
V2H vs a home battery — which wins?
For pure outage backup, V2H wins decisively. A $5,000 bidirectional charger + your existing EV gives you 5-10x the runtime of a $15,000 Powerwall. For daily cycling (time-of-use arbitrage, solar shifting), home batteries win — daily EV cycling for V2G would degrade your car battery faster than a stationary battery's 10-year warranty covers. Rule of thumb: V2H for backup (1-2 outages/year), home battery for daily cycling.
Loadshedding-specific guidance (South Africa)
South African loadshedding stages 2-4 typically mean 2-4 hours off per stage. A 75 kWh EV with V2H at 60% usable + 90% efficiency = 40.5 kWh available. At a 500W essential load, that's 81 hours of runtime — over 30 loadshedding events. Even at Stage 6 (8+ hours/day off), your EV easily covers it. The bidirectional charger pays back in 1-2 years vs buying a generator + fuel.
Battery degradation concern
V2H cycling does use your EV battery. However, modern EV batteries are rated for 1,500-3,000 full charge cycles before significant degradation. Even daily V2H use (1 cycle/day) would take 4-8 years to reach 1,500 cycles — by which time the battery is already aged from calendar degradation anyway. For occasional backup use (10-20 cycles/year), the impact is negligible. Avoid daily deep discharges below 30% if you're concerned about longevity.
The "always plugged in" lifestyle
V2H works best when your EV is plugged in whenever you're home. This means you can't use V2H as a backup while you're at work — the car isn't connected. For true whole-home resilience, pair V2H with a small home battery (5 kWh) that handles brief outages during the day; the EV takes over when you get home. This hybrid setup gives you 24/7 backup at a fraction of a full battery bank cost.
Frequently Asked Questions
Yes, if your EV supports V2H (Vehicle-to-Home). Compatible 2024+ EVs include Ford F-150 Lightning, Chevy Silverado EV, Hyundai Ioniq 5/6, Kia EV6/EV9, Nissan Leaf (CHaDeMO), and Tesla Model 3/Y (with Powershare). You'll need a bidirectional charger ($4,000-6,000 installed) and a compatible EV.
A 77 kWh EV with 60% usable at 500W essential load can power your home for 80+ hours (3+ days). At 1200W typical load, expect 30-40 hours. At 2500W full home load, expect 15-20 hours. Use the calculator above for your specific setup.
For backup power, yes. A $5,000 bidirectional charger with your existing EV gives 5-10x the runtime of a $15,000 Powerwall. For daily cycling (time-of-use arbitrage, solar shifting), a home battery is better — daily EV cycling for V2G would degrade your car battery faster than its warranty covers.
Minimal impact for typical backup use. Modern EV batteries are rated for 1,500-3,000 full cycles. Occasional backup use (10-20 cycles/year) is negligible. Daily deep V2H cycling (1 cycle/day) would consume your battery warranty in 4-8 years — comparable to normal calendar aging. Avoid discharging below 30% regularly if longevity is a concern.
Ford Charge Station Pro (Lightning only, $1,310 + install), Wallbox Quasar 2 (CCS, ~$4,000 installed, works with most CCS EVs), Fermata FE-15 (premium home integration, ~$6,000). Tesla Wall Connector with Powershare works for 2024+ Teslas only. Get at least 3 installer quotes — pricing varies widely.
Yes — V2H is ideal for loadshedding. A 75 kWh EV at 60% usable + 90% efficiency gives 40+ kWh, enough to power essentials (500W load) for 80+ hours. That covers Stage 6 loadshedding (8+ hours/day off) for over 10 days without recharging. Pair with solar to recharge the EV during the day for indefinite backup.
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