On-grid or Grid-Connected photovoltaic power systems are power systems energized by photovoltaic panels, which are connected to the utility grid. Grid-connected photovoltaic power systems consist of photovoltaic panels, mppt controller, Solar inverters, power conditioning units and grid connection equipment.
Unlike stand-alone photovoltaic power systems these system seldom have batteries. When conditions are right, the grid connected PV system supplies the excess power, beyond consumption by the connected load, to the utility grid.
How It Works?
Residential grid-connected photovoltaic power systems which have a capacity less than 10 kw can meet the load of most consumers. They can feed excess power to the grid, which in this case acts as a battery for the system. The feedback is done through a meter to monitor power transferred. Photovoltaic wattage may be less than previously. If photovoltaic wattage substantially exceeds average consumption, the energy produced by the panels will be much in excess of the demand.
In this case, the excess power can yield revenue by selling it to the grid, depending on their agreement with their local grid energy company, the consumer only needs to pay the cost of electricity consumed less the value of electricity generated. This will be negative number if more electricity is generated than consumed. Additionally, in same cases, cash incentives are paid from the grid operator to the consumer.
Solar energy gathered by photovoltaic solar panels, intended for delivery to a power grid, must be conditioned, or processed for use, by a grid-connected inverter. This inverter sits between the solar array and the grid, draws energy from each, and may be a large stand-alone unit or may be a collection of small inverters, each physically attached to individual solar panels. The inverter must monitor grid voltage, waveform, and frequency. One reason for monitoring is if the grid id dead or strays too far out of its nominal specifications, the inverter must not pass along any solar energy. An inverter connected to a malfunctioning power line will automatically disconnect in accordance with safety rules.
A grid connected photovoltaic power system will reduce the power bill as it is impossible to sell surplus electricity produced to the local electricity supplier.
Grid connected PV systems are comparatively easier to install as they do not require a battery bank system. Grid interconnection of photovoltaic (PV) power generation systems has the advantage of effective utilization of generated power because there are no storage losses involved.
A photovoltaic power system is carbon negative over its life span, as any energy produced over and above that to build the panel initially off sets the need for burning fossil fuels. Even though the sun does not always shine, any installation gives a reasonably predictable average reduction in carbon consumption.