If you own a Hyundai Inster in Japan and your rooftop solar has been stubbornly refusing to fill its battery through your V2H unit, help arrives today. Hyundai Mobility Japan starts offering a vehicle software update for the Inster on Monday, October 19, to fix a solar-charging glitch with certain Nichicon and Denso vehicle-to-home (V2H) units. Kona owners: you’re still waiting.
The update at a glance
- What: An improvement software update for the vehicle (Hyundai hasn’t published a version number or full release notes).
- Who gets it: Hyundai Inster owners in Japan, starting October 19, 2026. The Kona Electric fix is still targeted for “within 2026,” with no date yet.
- Affected V2H units: Nichicon VSG3 series and VCG series, and Denso SD series and D series.
- How it’s delivered: Not over the air. It’s done at Hyundai service locations around Japan, both Hyundai-run and partner shops. Contact your nearest one to book.
- Region: Japan. This is a fix for Japanese V2H hardware, not a global software release.
What it fixes
According to Hyundai Mobility Japan’s October 16 notice, there’s only one change, and here it is in plain English:
- Stable solar-surplus charging through V2H. When an Inster or Kona is connected to one of the V2H units above and charging from surplus home solar power, the car and the charger sometimes didn’t coordinate properly “under specific conditions,” so the charging power wouldn’t ramp up. In other words, you could have spare sunshine on the roof and a car plugged in, and the car would still trickle-charge. The update changes the vehicle-side software so the two work together properly.
That’s the whole list. Hyundai’s notice doesn’t mention any other features or changes, so we won’t either.
A long road to a small fix
Inster owners waited a while for this. Hyundai’s own notices show the timeline:
- May 12: Hyundai confirms the problem, says it will fix it on the vehicle side as the “fastest and most certain” option, and targets late August for both models.
- September 3: The date slips. Inster moves to early October, Kona to “within 2026.”
- October 16: Inster gets a firm date of October 19. Kona stays at “within 2026,” with an update to follow once a date is set.
Hyundai apologized in its notice for causing customers “inconvenience and worry over a long period.” As EV Note points out, the notice doesn’t list affected production dates or VIN ranges, the cost of the update, how long the work takes, or whether loaner cars are available. It also doesn’t say whether this is a recall, an improvement campaign or a service campaign, so don’t assume it’s a safety recall. Ask the service center when you book.
Why V2H matters in Japan
V2H is a bigger deal in Japan than in most markets. Lots of homes pair rooftop solar with a V2H unit, using the car’s battery as a home battery for self-consumption and for backup during earthquakes and typhoons. Nichicon and Denso are two of the biggest names in that market. Denso’s compatibility list covers Inster versions with 42.0 kWh and 49.0 kWh batteries and Kona versions with 48.6 kWh and 64.8 kWh. A car that won’t take full advantage of free solar power undercuts one of the main reasons to set up V2H in the first place.
What owners should do
- Inster owners using a Nichicon VSG3/VCG or Denso SD/D unit: call your nearest Hyundai service location to book the update. Hyundai’s customer center is 0120-600-066 (weekdays, 9:00 to 18:00).
- Kona owners: keep an eye on Hyundai Mobility Japan’s notices page. Hyundai says it will post the start date once it’s confirmed.
The EVX News take
It’s good to see this fixed, but the timeline is a reminder of how much easier this is when updates arrive over the air. A five-month wait and a dealer visit for a charging-logic fix feels very 2015. Still, Hyundai deserves credit for explaining the issue clearly and keeping owners updated. Japanese homes that combine solar, V2H and an EV are a big part of the clean-energy picture here, so every fix like this helps.
Sources: Hyundai Mobility Japan (Oct. 16 notice), Hyundai Mobility Japan (Sept. 3 notice), Hyundai Mobility Japan (May 12 notice), EV Note, Denso V2H compatibility list.
— The EVX News team
Featured image: “Hyundai Inster DSC 8778 (cropped)” by Alexander Migl, via Wikimedia Commons, licensed CC BY-SA 4.0.
