Solar panels (PV) with battery storage takeoff

A solar array on a pitched roof is fixed through the covering to the rafters beneath it. On a tiled or slated roof the tiles are lifted at each fixing, a hook is screwed to the rafter, and the tile beneath is notched so the tiles lie flat over it again; on an asphalt shingle roof a flashed mount goes through the covering and is lapped under the course above. Aluminium rails bolt to the hooks, and the panels (modules) clamp to the rails. How many panels, how they are strung together and how large the inverter and the battery are come from the array's design for the roof's direction, its shading and what the house uses; the solar pages on this site that answer those are sizing pages, and none is a row here. Where the panels may go is the design's too: in the US the codes keep clear pathways and setbacks round an array for firefighters, and in the UK the mounting system's wind design may keep panels off the roof's edges. Whether the rafters carry the array, with the wind and snow on it, is an engineer's question on an older or altered roof, a question this page raises and leaves to the engineer, and the hooks are a provisional item, their number known once the rafters are found.

Almost everything after the rails is electrical work, and most of it is on the DC side, which cannot be switched off while light falls on the panels. Each panel's leads are clipped to its frame as it goes on, and plugging them into strings is the installer's work as the DC cable is run down through the roof to the inverter; where that cable enters the roof it is weathered with a cable-entry tile or a sealed gland. The inverter hangs where it can shed its heat, with a DC isolator beside it, or with rapid shutdown devices at the array where the US code asks for them, and its AC side is a new circuit to its own way in the consumer unit (service panel) through a local isolator (a disconnect). Labels at the board, the meter and every isolator tell the next electrician, or a firefighter, that the house has a second source of supply. The battery connects to the inverter or to its own, and where it may stand is written down: PAS 63100 in the UK, and the residential code's energy storage rules and NFPA 855 in the US, restrict where it may go, keeping it out of bedrooms among other places, and may ask for a smoke or heat alarm where it stands.

The rows are the two things on this job a page measures: the scaffold face the array is fixed from, with the edge protection at the eaves and a loading bay for the panels, and the waste. A British installer works from a scaffold; a North American crew also works from ladders, harnessed to anchors on the roof, and where no scaffold goes up its length is 0 and its row goes too. Everything else is listed, with its condition where it has one: the network operator's notice or application (G98 or G99 in Great Britain, the utility's interconnection agreement in North America), the hooks, the rails and panels, the DC cabling, its isolation and labels, the inverter with its generation meter, its circuit and isolator, a new board where the old one cannot take a second source, the battery and any alarm the rules ask for, bird mesh where it is wanted, and the tests. The inverter's settings, with any export limit the network operator sets, are entered as it is switched on after the tests. In the UK an export payment or a grant rests on the installation being registered under MCS, and its MCS certificate comes with the handover; across North America the permit's inspections and the utility's permission to operate come before the system runs.