How to Charge Your EV With Solar Panels

Charging an EV from solar panels is straightforward in principle — route surplus generation into the car instead of exporting it to the grid. In practice, it requires a specific type of charger, a current transformer fitted in your consumer unit, and some understanding of when and how the system operates. This guide walks through exactly what you need, how to set it up, and what savings are realistic. For a broader overview of the whole topic including charger comparisons and sizing, see our complete guide to EV charging with solar panels.

What you need

Three things are required for genuine solar EV charging:

• A solar PV system that generates more than your household is using at certain points during the day. The surplus is what gets diverted into the car.
• A solar-divert EV charger — not just any smart charger. The charger must be able to read your live generation and consumption data and adjust its charge current accordingly.
• A CT clamp (current transformer) fitted in your consumer unit. This measures the current on your import/export cable in real time and tells the charger whether surplus is available and how much.

Without the CT clamp, there is no solar divert. The clamp is what makes the system reactive to actual generation rather than a fixed schedule. It is fitted by the installing electrician during charger installation.

Choosing a charger

The myenergi Zappi is the most widely used solar-divert charger in the UK and the one most installers are familiar with. The CT clamp is included in the kit. It offers three charge modes and adjusts in 1A steps as generation changes.

The Ohme ePod is a different proposition: it optimises charging around dynamic electricity tariffs such as Octopus Agile, but it does not read live solar generation. It is a strong option for dynamic-tariff charging and a poor one for solar divert. Do not assume all “smart” chargers support solar.

For a full breakdown of which chargers have genuine solar divert and which do not, our solar-compatible EV chargers explained article covers the category in detail. For a ranked shortlist, see the best EV charger for solar panels UK guide.

Setting up solar divert

Once installed, setup involves three steps:

1. Confirm CT clamp placement

The CT clamp goes on the live conductor of your main import/export cable at the consumer unit — the cable connecting your meter to the board. Your installer does this. It must sit before any generation source feeds into the circuit, so it reads true import/export rather than just consumption. Most installers are familiar with the correct placement for Zappi and similar units.

2. Set the charge mode

On a Zappi, you choose between Eco, Eco+, and Fast. Eco draws the minimum charge current (6A, around 1.4kW) from the grid to maintain the session, topping up with available solar surplus. Eco+ waits for surplus to cover the full minimum current before starting, and pauses when surplus drops — no grid is drawn. Fast ignores solar entirely and charges at full rate from whatever source is available.

Eco+ is usually the right default during daylight if you want to maximise solar use. Many households use Eco+ during the day and set a scheduled Fast charge overnight to guarantee the car is ready by morning.

3. Test and observe

On a clear day with the car plugged in, watch the charger app or display. In Eco+ mode you should see the charge current rise and fall as clouds pass and household loads switch on and off. If the charger is not responding to generation, check the CT clamp is on the correct conductor and correctly oriented (most clamps are directional).

Realistic savings

The saving comes from the difference between what you would earn exporting and what you save by not importing. At a typical SEG rate of around 5p/kWh and a grid import rate of 28p/kWh, diverting rather than exporting saves around 23p per kilowatt-hour. Diverting around 3,000 kWh per year could save around £690 per year — but that figure depends on your array size, driving pattern, and whether the car is regularly plugged in during daylight hours.

A household with a 4–6kWp array that works from home, parks in the driveway, and drives regularly is well placed to achieve savings near that level. A household where the car is mostly absent during the day, or where the array is small, will see proportionally less benefit.

For a broader comparison of where surplus is best used, including hot water and battery storage, see our solar diverter vs battery vs EV charging article.

What to do when surplus is low

On overcast days or during winter months, surplus may not reach the 1.4kW threshold consistently. In Eco+ mode the charger simply waits; the car may not charge at all during a dull day. For households that need the car charged reliably by a given time, the practical approach is to use Eco+ during daylight and set a backup scheduled charge overnight at a fixed time. This way the car always has enough range regardless of generation, while still capturing whatever surplus is available during the day.

Most solar-divert charger apps let you set a minimum state of charge target alongside the Eco+ mode, so the scheduled backup only kicks in if the car hasn't already received enough energy from solar during the day.

When solar divert makes the most sense

Solar divert works best when:

• The car is regularly plugged in at home during daylight hours (weekdays at home, weekends).
• Your array generates meaningful surplus after household loads — typically a 4kWp-plus system in spring and summer.
• You drive enough to benefit from the additional charge (light drivers may fill the battery quickly and rarely need midday top-ups).

It works less well when the car is rarely home during daylight, when the array is small relative to household demand, or during winter months when generation is low across the board. Solar divert is a spring-to-autumn feature for most UK households; winter charging will come largely from the grid regardless of charger type.

Installation

EV charger installation must be carried out by a qualified electrician registered under a competent person scheme. The work includes mounting the charger, running cabling from the consumer unit, fitting the CT clamp, and notifying building control. Most installations take around half a day. Some installers — particularly those who also fit solar — offer a combined solar-and-charger quote which can simplify the process.

For products beyond EV chargers, such as a dedicated hot-water diverter to run alongside your charger, the myenergi eddi is worth considering. To compare quotes from local installers, use our free quotes tool.