EV charging: plug in at six, leave at eight

Smart EV charging shifts a 50 kWh top-up from peak hours (around €45 cost in Estonia) to cheap night hours (around €15 cost), saving 50–70% on the same energy. The OCPP-compatible wallbox plugs in at 18:00 and leaves at 08:00 — fourteen hours where Volton's aggregator algorithm picks the cheapest sub-set of hours to actually charge against the day-ahead price curve.

The best feature of an electric car is also its most boring: it is the most patient appliance in the house. It plugs in at six in the evening, leaves at eight in the morning, and during those fourteen hours it does not particularly care which minutes the actual charging happens in.

That patience is worth real money on the spot market. A car needs roughly four hours of charging out of those fourteen, and on a typical Estonian winter night the cheapest hour can be five to ten times cheaper than the most expensive one. Same car, same kilowatt-hours, same socket — the bill changes by a factor of three depending on which four hours you use.

Estonia runs on the Nord Pool day-ahead market, where prices are published the afternoon before and can swing five to ten times between the cheapest and most expensive hour of the day. You can see tomorrow’s curve yourself on Elering's public dashboard. The night dip between 02:00 and 06:00 is usually the cheapest window; the morning and evening peaks are usually the worst place to be drawing 11 kW.

A static timer that says "charge from 02:00" was great in 2020. It is no longer enough. Cheap hours move around: some days the trough is at 03:00, some days the wind blows hard at 14:00 and the middle of the afternoon is the bargain. Smart charging re-optimises every day against tomorrow’s prices. For a deeper look at how the day-ahead auction actually works, see our guide to day-ahead spot prices.

Solar changes the picture again. When your roof is pushing more kilowatts into the house than the house is using, the export price you get back is almost always lower than the retail price you would have paid for the same energy later. Redirecting that surplus into the car is one of the highest-return moves in a residential energy setup, and it pairs naturally with a heat pump or hot water tank as the secondary sink.

There is a battery-health bonus on top of the price arbitrage. Charging at 3.7 or 7 kW across six gentle night hours is easier on the pack than blasting it at a 50 kW DC stall, so the slow, cheap, planned charge is also the kind your battery prefers. Vehicle-to-grid, where a few models like the Nissan Leaf and newer BYD and Hyundai cars can discharge back into the home, is still niche in Estonia, but it is the obvious next chapter once bidirectional chargers come down in price.

Most modern wallboxes sold here speak OCPP 1.6 or 2.0, which is the open protocol that lets a third-party optimiser drive the charger over the internet. Eleon, Easee, Wallbox, KEBA, ABB Terra and Schneider EVlink all expose it. If you are buying a charger this year, OCPP support is the one box you must tick; without it you are locked into whatever app the manufacturer ships, which is often a glorified timer.

You also do not want to chase prices manually. Checking Elering at 22:00 every night to set tomorrow’s schedule gets old after a week, and you will miss the days that matter most. The point of automation is that it runs while you sleep.

This is what Volton Home does. The app connects to the charger over OCPP, pulls tomorrow’s spot prices, and schedules charging across whatever parking window you give it, whether that is overnight or weekend daytime when solar is strong. If you also have panels, the solar post covers the surplus-to-EV side.