Think of it as the EV’s onboard charger acting like an inverter both ways: it pulls AC from the house/grid to charge, and can also push AC back to the house/grid for V2H/V2G. That’s different from today’s common DC V2H boxes (which handle inversion inside the wall unit).
What it is (and why it’s hot)
- AC bidirectional (aka “duplex AC”) = BPT on AC per ISO 15118-20: the car and EVSE negotiate a two-way session; the car’s onboard charger inverts when discharging. (switch-ev.com)
- DC bidirectional (e.g., Wallbox Quasar 2 for Kia EV9) = the wall unit handles the DC↔AC conversion; the car just opens the DC path. (InsideEVs)
Where Volvo & Kia are
- Kia (EV9): Public V2H is already rolling out with DC bidirectional (Quasar 2 + Kia Power Recovery Unit), launched in selected markets in 2025. Independent trials and Kia press confirm EV9 is V2H/V2G-capable. Research demos with ISO 15118-20 also show 11 kW bidirectional operation (tech ready; certificates + utility rules are the hurdles). (kiamedia.com)
- Volvo: Volvo has been investing in bi-directional across its EV roadmap (Volvo Cars Energy unit; tech explainer), but hasn’t publicly shipped a home V2H kit yet. AC or DC implementations could arrive depending on markets and partner hardware. (Green Car Reports)
AC vs DC bidirectional: quick take
- AC (duplex)
- Pros: cheaper wallbox (no big inverter), simpler installs, leverages car’s hardware.
- Cons: needs cars with ISO 15118-20 AC-BPT enabled; today’s real-world availability is limited; utility/grid compliance still evolving. (switch-ev.com)
- DC (today’s mainstream pilots)
- Pros: works now with supported cars (e.g., EV9), certified products exist; easier utility interop in some regions.
- Cons: pricier wall unit; bulkier; dedicated gear per car/grid. (InsideEVs)
Power & standards (what to expect)
- Power levels: AC bidirectional pilots commonly target 7.4–11 kW both directions; EV9 lab work showed ~11 kW AC BPT. DC units vary (5–10 kW home, higher for commercial). (evs38-program.org)
- Comms/interop: ISO 15118-20 (BPT + Plug&Charge), often paired with SAE J2847/3 (AC V2H/V2G) or J2847/2 (DC) in some markets; certificate management & utility rules are the gating items. (California Energy Commission)
What this means for you (Volvo & Kia owner)
- Kia EV9 today: If your market supports it, V2H via DC (Quasar 2 + Kia setup) is real. If you specifically want AC duplex, watch for firmware + AC-BPT wallboxes as ISO 15118-20 deployments expand. (kiamedia.com)
- Volvo (EX90/next-gen): Volvo is openly building toward bidirectional features; exact AC vs DC path and home hardware partners are not formally released for Sweden yet. Track official Volvo Energy/Volvo Cars updates. (Green Car Reports)