Dynamic Solar Diversion - the CT Clamp at Work
The financial case for solar diversion is decisive: every unit of surplus generation absorbed by your EV displaces a unit of grid electricity worth four to eight times what the grid would have paid you for it.
A CT clamp at the main incomer measures instantaneous net power flow every second. When generation exceeds all household loads combined, the surplus that would otherwise travel to the grid is detected by the charger firmware, which ramps its current draw from the minimum 6A threshold upward to absorb it - maximising the proportion of solar captured in the vehicle. On a clear Surrey summer day with a 6kWp array and a Zappi in Eco+ mode, it is routine to achieve a full day's charge from surplus generation alone, at an effective per-mile cost of zero.
- Real-time CT monitoring: net power flow sampled every second at the incomer - charge rate adjusts within seconds of generation changing
- Minimum 6A threshold: charger maintains a trickle below which diversion cannot operate, ensuring the vehicle always progresses if plugged in
- Eco+ mode: charges exclusively from surplus PV - zero grid draw until solar surplus exceeds the 6A minimum, then ramps charge rate instantly
- Zero-carbon mileage: every kWh diverted from your panels instead of the grid eliminates the corresponding carbon cost from your vehicle's operation
Smart Charging Modes - Precision Control via App
A solar-diversion charger is not a binary on/off device. It offers a hierarchy of intelligent modes that give the homeowner complete control over the trade-off between green credentials and charging speed.
The Zappi's three charging modes span the full spectrum from pure solar to pure grid. In 100% Green (Eco+) mode, the charger draws only from confirmed surplus solar generation - it will not take a single watt from the grid, even if that means charging slowly on a partly cloudy afternoon. In Eco mode, the charger blends solar surplus with a minimum grid top-up to maintain a continuous charge session. In Fast mode, the charger draws at full 7kW from the grid when time is critical. All three modes are accessible from the myenergi app and can be scheduled automatically by time of day, generation forecast, or departure time.
- 100% Green (Eco+) mode: absolute zero grid draw - only genuine surplus solar powers the vehicle, regardless of how long charging takes
- Eco mode: blended mode combining solar surplus with minimum grid draw to keep charge sessions continuous on lower-generation days
- Fast mode: full 7kW grid draw when departure time demands a fully charged vehicle regardless of current generation
- App and schedule control: mode switching, charge targets and departure times managed from the myenergi app - no manual intervention at the charger required
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The Winter Strategy - Octopus Intelligent Grid Fallback
The question every solar homeowner asks is: what happens in January, when the panels generate a fraction of summer output and the car still needs to be fully charged every morning?
The answer is automated grid tariff integration. The Zappi connects directly to the Octopus Intelligent API, which transmits half-hourly grid pricing data in advance. In the absence of sufficient solar surplus, the charger transitions seamlessly to ultra-low-cost overnight grid electricity, scheduled to coincide with the cheapest off-peak windows: typically between midnight and 5am at rates as low as 7p per kWh. The vehicle is fully charged by morning. The running cost is near zero. For a Porsche Taycan owner driving 12,000 miles annually, this combination reduces annual charging cost from approximately 1,800 GBP at standard rates to under 300 GBP across the full year.
- Seamless seasonal transition: Zappi automatically switches between solar diversion and grid fallback based on live generation data - no manual setting changes
- Octopus Intelligent API: half-hourly pricing data received in advance - cheapest windows scheduled without any homeowner input
- Typical winter off-peak rate: 7p to 12p per kWh overnight versus 25 to 35p per kWh at peak daytime rates
- Year-round financial model: solar covers summer mileage for free; Octopus Intelligent reduces winter charging to near zero cost
Elite Installation - Wireless CT, Concealed Cabling and DNO Compliance
A solar-diversion installation is technically more complex than a standard EV charger - it requires CT monitoring hardware at the incomer, a communication link to the charger, and dynamic load management to protect the main fuse across combined solar, EV and estate loads.
Where routing a CT data cable from the consumer unit through finished surfaces would compromise the property's aesthetic - period cornicing, oak flooring, or kitchen finishes - we deploy wireless CT hardware transmitting on a dedicated 868MHz radio frequency, eliminating the need for any additional conductor through the building fabric. Dynamic Load Balancing ensures the combination of solar generation, EV charging and all estate loads never exceeds the main fuse rating. DNO notification - required for any charger above 3.68kW on a PME supply - is submitted by our team on your behalf, with the reference number included in your handover pack.
- Wireless CT option: 868MHz radio-frequency consumption monitoring eliminates additional data cabling through finished building fabric
- Concealed wired CT route: where wireless is not optimal, CT cable routed through agreed concealed paths before charger installation
- Dynamic Load Balancing: combined solar, EV and estate load managed to protect the 100A main fuse at all times during simultaneous operation
- DNO notification management: G98 or G99 notification submitted by our team as a standard element of every installation - reference number in handover pack
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