In-roof solar and battery for a loft conversion in Haversham

A homeowner in Haversham wanted a lower electricity bill. A loft conversion already underway turned a straightforward solar job into an in-roof build designed around three new roof windows.

Black in-roof solar panels set flush into a tiled roof in Haversham, with two roof windows alongside

Quick facts

System size: 4.55 kWp
Panels: 10 × Trina TSM-450NEG9R.25, 450 W
Mounting: GSE in-roof, portrait
Inverter: Fox ESS H1-5.0-E-G2, 5 kW hybrid
Battery: Fox ESS EP12 — 11.52 kWh nominal, 10.4 kWh usable
Backup: No whole-home backup
EV charger: None
Roof: Concrete tiles, south-facing, 35° pitch, one face
Grid connection: G99, approved the day it was submitted
Installed: May 2026
MCS estimated generation: 4,388 kWh a year
Estimated savings: £1,174 a year
Estimated payback: 9.2 years

Estimated at quote stage based on the customer’s usage and tariff at the time. Actual savings vary.

Why they got in touch

A homeowner in Haversham wanted their electricity bill down, and wanted it done quickly. The house is a semi-detached with a single south-facing roof face, and a loft conversion was already underway — which turned out to decide the whole shape of the job.

What we recommended and why

Because the roof was being opened up anyway, we proposed an in-roof array rather than panels on brackets above the tiles. In-roof sits flush in place of the tiles, so on a roof that is being reworked it looks like part of the building rather than something added to it. The catch is that it has to be designed around everything else going into that roof — here, three new pivot roof windows.

We paired 10 × 450 W panels with a Fox ESS H1 5 kW hybrid inverter and a Fox EP12 battery, sited in the back garden. The battery was chosen on cost-effectiveness and the strength of its warranty rather than on headline capacity.

The install

This was the complicated one. The GSE in-roof system had to integrate fully with three Condell MK08 pivot windows, using Velux solar integrator kits and GSE adaptor frames so that the panels, the windows and the roof covering all weatherproof into each other. A chartered engineer produced a structural report before anything went on the roof.

The roof work was done on 8 May, with the electrical side following on 11 and 12 May. The G99 application went to the network operator on 5 May and was approved the same day, so the grid connection never held the job up.

The result

A 4.55 kWp array that reads as part of the roof rather than an addition to it, with 11.52 kWh of storage behind it. The MCS certificate puts estimated generation at 4,388 kWh a year.