Solar PV, Home Batteries and Virtual Power Plants

About this course.

Rooftop solar PV works by converting sunlight directly into electricity using photovoltaic panels, which is then converted from direct current (DC) into the alternating current (AC) that homes and the grid use, so the household can power its appliances with its own generation and export any surplus. The panels contain photovoltaic cells that generate DC electricity when light falls on them; an inverter converts that DC into AC; and the AC electricity flows first to the home's own loads, with any excess exported to the grid and any shortfall drawn from the grid. In Australian homes, rooftop solar plays the role of reducing the electricity a household buys, lowering bills and emissions, and — increasingly, with storage and VPPs — turning the home into a small participant in the wider electricity system.

The underlying physics is worth understanding at a basic level. A photovoltaic cell is made from semiconductor material that releases electrons when struck by light, producing a flow of direct current. Many cells are combined and encapsulated into a panel (or module), and panels are wired together into an array on the roof. The amount of electricity generated at any moment depends on how much sunlight reaches the panels, which varies with the time of day, the season, the weather, the orientation and tilt of the panels, and any shading. Because generation follows the sun, a rooftop system produces most in the middle of clear days and nothing at night, which is central to understanding both its value and the role of storage.