Solar EV charging explained

Why solar charging is worth it

Feed-in tariffs pay a fraction of the retail electricity rate for exported solar. Using that same energy to charge your car instead means you're effectively charging at a much lower cost than importing from the grid.

How solar-aware chargers work

A solar-aware charger monitors your home's import/export in real time (usually via a CT clamp on the main switchboard, or direct integration with your inverter) and adjusts the charging current so it uses surplus generation rather than drawing from the grid.

• Surplus-only mode — charges only from exported solar, slows or pauses when a cloud passes
• Boosted/hybrid mode — guarantees a minimum charge rate, topping up from the grid when solar isn't enough
• Scheduled mode — combines solar during the day with off-peak grid charging overnight

What you need for it to work well

A rough guide is that you generally need over a kilowatt of genuine surplus generation before single-phase surplus-only charging becomes practical — below that, the car may start and stop charging often.

The car also needs to be plugged in during daylight hours for solar charging to help, which suits people who are home during the day or charging on weekends more than daily commuters who leave the car parked elsewhere.

Battery and inverter interactions

If you have a home battery, it's worth deciding whether the battery or the car gets priority over surplus solar — most setups let you configure this so the battery isn't starved by the car, or vice versa.

Chargers with their own CT clamp generally work with any inverter brand; native inverter integrations (like Fronius Wattpilot) can be simpler to set up if you already have that inverter.