Ravenstone Cottage

A listed slate roof in a conservation area, which sets the mounting method before anything else is decided.

In-roof, not on-roof

The planning officer accepted an in-roof tray system on the condition the array sat flush with the surrounding slate and stayed off the ridge line. That means the slates come off by hand, the tray goes in, and the slates go back around it.

It adds roughly two days of labour against a standard rail mount. It is the only version of this job that was ever going to be approved.

Why four kilowatts and not six

Two people, both out of the house from eight until six. Self-consumption was measured at thirty-four percent from a fortnight of half-hourly data off the smart meter. Adding two more kilowatts would have added generation that leaves at five pence.