The brief
Dr. Patel wanted the system sized for real consumption, not a marketing sweet spot. His last 12 months of smart-meter data showed an average 3,900 kWh electricity use and a peak of 18kWh in winter. He didn't want to oversize the battery or undersize the array.
The roof had 14m² of unshaded south-facing pitch at 35°. Perfect for a 10-panel 4.2kW string without compromising aesthetics on the conservation-area street frontage.
What we installed
10 × 420W all-black monocrystalline panels on integrated flush mounts, a 5kW hybrid inverter, and a 10kWh battery positioned in the understairs utility cupboard. Smart Export Guarantee tariff was filed with Octopus on the day of commissioning — export rate secured at 15p/kWh.
MCS certificate issued within 10 working days. We also programmed the battery to charge from grid during Octopus Agile's sub-10p overnight window as a further saving.
The outcome
12 months post-install, grid imports are down 78%. Annual bill dropped from £1,840 to £312 — a combination of self-consumption, overnight cheap-rate charging, and SEG export revenue of roughly £180/year. EPC re-rating took the property from C 72 to B 84.
Projected payback is 7 years and 2 months on the installed cost of £11,450. 25-year product guarantee on the panels, 10 years on the inverter and battery.
“Everyone else tried to sell me panels. OMEGA asked what I used and designed a system around the data. First winter we were off-grid between 11pm and 6am, every night.”