Solar & Battery December 2025

5kW Solar & Battery on a Flat Roof Extension in Trowbridge

Trowbridge, Wiltshire (BA14) — 3-bed semi-detached with flat roof extension

A semi-detached home where the main roof faced east-west, making it unsuitable for a traditional south-facing array. The homeowner also had a large flat-roof extension that offered an alternative mounting opportunity.

4,900 kWh
Annual generation
£1,340
Annual saving
1,147 kg
CO2 saved/yr

The Challenge

The pitched roof had an east-west orientation giving reduced yield. The flat-roof extension had good southern exposure but required specialist mounting frames and membrane protection to avoid voiding the EPDM rubber roof warranty.

Our Solution

We installed 8 panels on the flat roof using ballasted tilt frames angled at 15 degrees for optimal generation without penetrating the membrane. The remaining 4 panels were placed on the east-facing pitched roof to capture morning sun. A 10kWh battery maximises self-consumption.

The Result

The split array approach generates 4,900 kWh annually — more than a pure east-west pitched installation would have achieved. Self-consumption with battery is 79%. Bills dropped from £165/month to approximately £40.

“Two other companies said our roof was not suitable. Lumos found a way to use both our flat roof and the east pitch together. The generation is better than we expected.”

S

S. Pearce

Trowbridge, Wiltshire

System Specifications

System size 5 kW
Battery capacity 10 kWh
Property type 3-bed semi-detached with flat roof extension
Roof type Flat roof (EPDM) + pitched concrete tiles
Panels 12 x AIKO Neostar 2P 450W All-Black
Inverter Sigenergy SigenStor 5kW Hybrid
Battery unit Sigenergy SigenStack 10kWh
Completed December 2025

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