Project Summary
Client: The Roberts Family, Altrincham
System: 8.4kW solar PV with 13.5kWh Tesla Powerwall and Zappi EV charger
Completion: Autumn 2023
Annual Savings: £2,800
CO2 Reduction: 2.4 tonnes per year
The Challenge
The Roberts family had recently moved to a substantial five-bedroom detached property in Altrincham and were planning a comprehensive energy upgrade as part of their renovation works. With three young children, two electric vehicles, an air source heat pump for heating, and a home office where Mr Roberts worked four days per week, the household's annual electricity consumption was substantial — exceeding 18,000 kWh per year. Their initial energy bills had been a shock, totalling over £4,800 in their first year of occupation.
The family wanted a comprehensive solution that would address all aspects of their energy use: maximum solar generation to displace as much grid electricity as possible, substantial battery storage to capture surplus for evening use, intelligent EV charging integrated with the solar system, and detailed monitoring to help them understand and optimise their consumption patterns. Aesthetics were also important — the property was prominently visible from the road and the family wanted any solar installation to enhance rather than detract from the property's kerb appeal.
Our Solution
The property's substantial roof area and excellent south-facing aspect allowed us to design a generous 8.4 kWp solar installation using 21 premium SunPower Maxeon 6 panels. These panels offer industry-leading efficiency (over 22%), exceptional aesthetics with integrated black backsheet and frames, and a 40-year performance warranty — the longest available in the market. While more expensive than standard panels, the Maxeon panels were ideal for this application given the family's premium expectations and long-term occupation plans.
For battery storage, the Roberts family chose the Tesla Powerwall, attracted by its sleek design, comprehensive smartphone app, and proven reliability. We installed a single Powerwall providing 13.5 kWh of usable storage, with backup gateway capability to provide whole-home backup power during grid outages. The Powerwall is mounted in the garage where it's hidden from view but easily accessible for monitoring.
The EV charging system uses a Zappi from myenergi, mounted on the garage exterior in a position convenient for both family vehicles. The Zappi's intelligent integration with solar systems means surplus generation automatically diverts to charge whichever vehicle is plugged in, providing free, zero-carbon transportation energy throughout the day. We configured the system to prioritise the family's primary vehicle (used most frequently for work commutes) while still allowing the secondary vehicle to charge as solar surplus permits.
Installation Process
The installation was completed over five working days, with our team coordinating with the broader renovation works being undertaken at the property. Significant elements included scaffold erection across the rear of the property, panel installation on the south-facing roof slope, electrical infrastructure installation including major upgrades to the consumer unit, battery and gateway installation in the garage, EV charger installation with appropriate cable routing, integration testing across all components, and homeowner training and handover.
The integrated commissioning was particularly important for this installation, ensuring that solar generation, battery operation, EV charging, and grid import/export all worked together seamlessly. Our commissioning engineer spent a full day testing different scenarios including high solar generation periods, evening high-demand periods, low generation winter days, and grid outage conditions, ensuring the system would deliver the predicted performance across all operating conditions.
Results and Performance
The system has been operating for approximately fifteen months at time of writing, with first-year performance exceeding our predictions. Annual generation has been 7,850 kWh against a predicted 7,400 kWh, partly due to favourable weather and partly because of the exceptional efficiency of the Maxeon panels.
The combination of substantial solar generation, intelligent battery management, and solar-powered EV charging has dramatically transformed the family's energy consumption profile. Grid imports have fallen by approximately 65%, with the remaining grid consumption being primarily during dark winter evenings. Annual savings total approximately £2,800, after accounting for both reduced grid imports and SEG export revenues for the modest summer surplus.
Perhaps more striking has been the impact on the family's transportation costs. Solar-powered EV charging has displaced approximately 7,500 miles of grid charging across the two vehicles, saving an additional £750-£900 per year compared to grid-rate charging. Combined with the avoided fuel costs of petrol or diesel vehicles, the family's total household energy costs have fallen from over £4,800 per year to under £1,200 per year.
Client Feedback
"Solar has completely transformed our home — our energy bills have plummeted, our cars effectively run on sunshine, and we feel really good about our environmental impact. Nova Volt designed and installed an incredibly sophisticated system that 'just works' — we don't need to think about it, but it's saving us a fortune. The entire team have been a pleasure to work with." — Mr Roberts, Altrincham
