CASE STUDY
Residential Project
An existing customer in Farnham, Surrey already had a comprehensive SolarEdge solar PV and battery storage system, including an 8kW three-phase Home Hub inverter, 23kWh of battery storage and a SolarEdge Backup Interface, alongside a Home Assistant smart home system. While this setup could already provide backup power, the homeowner wanted extra protection against longer outages, particularly in winter when solar generation is lower. Big Green Electrical was asked to add a diesel generator that would take over automatically if the batteries could no longer supply the home.
The Challenge
The European three-phase version of the SolarEdge Backup Interface does not include the dedicated generator connection or automatic generator-start features available on some North American systems. This meant there was no off-the-shelf way to add a generator to the property. We needed to design an electrical arrangement that would allow the home to run from either the SolarEdge battery system or the diesel generator, while guaranteeing the two could never operate together at the same time.
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The Solution
We installed a Warrior LDG12S3 three-phase diesel generator, chosen for its reliable, quiet and efficient standby power, alongside a dedicated three-phase distribution board and a Warrior automatic transfer switch (ATS). The switch operates across all three phases and the neutral (four-pole), keeping the battery-backed supply and the generator supply completely separate. We also gave careful consideration to the earthing arrangements, neutral-to-earth bonding and electrical protection needed when the home is running independently of the grid. The generator and automatic changeover system have been fully commissioned and tested.
The homeowner now has layered backup power that works entirely automatically. Day to day, the home runs on grid electricity, with solar and battery storage reducing imports and the generator switched off. If the grid fails, the SolarEdge Backup Interface isolates the property and the battery and solar take over, while Home Assistant switches off selected high-demand appliances to keep usage within what the system can supply. Should the battery no longer be able to support the home, the Warrior ATS detects the loss of supply, starts the generator and transfers the property onto generator power, keeping the lights on through even extended winter outages.
Backup protection, rather than electricity savings: the generator is a standby supply for extended power cuts. Solar and battery storage reduce everyday grid purchases; the generator consumes diesel and requires maintenance when used. No annual electricity-saving figure is attributed to the generator.
Quality guaranteed
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