A residential photovoltaic system is usually mounted on the rooftop of a building and typically feature a capacity of about 5 to 20 kW. Currently, in a grid connected rooftop photovoltaic system, the generated electricity can be sold to the grid at a price higher than what the grid charges to its consumers, providing an adequate payback to the investment made by the building owner. This way of financing photovoltaic energy production growth is widely used in many Countries and in the last 10 years led to a fast expansion of the solar photovoltaic industry worldwide. Main issues in residential applications are the following:
- an accurate measurement of energy flows between the private rooftop photovoltaic system and the grid to clearly define costs and revenues following the Feed In Tariff scheme to be applied. ABB offers a complete range of modular energy meters (EQ meters) compliant and tested according to the European MID directive, which allows meters to be used whenever an energy consumption reading is requested for billing;
- a reliable protection of the whole building electrical system from lightning, that is more likely to happen because of the metal structures mounted on the rooftop. ABB offers a wide range of surge protection devices (OVR PV) specifically designed for photovoltaic systems;
- monitoring energy flows between the rooftop photovoltaic system and the public grid in order to disconnect the first one in case of instability, faults or maintenance going on in the public grid and that could affect home appliances. ABB offers a multifunctional grid feeding monitoring relay range that offers the flexibility needed to integrate small and medium networks into the main grid.