Types of Solar systems

There are generally two types of PV systems: off-grid and grid-tied depending on their connection to the utility grid.

1. Off-grid DC/AC PV system: (DC without inverter, AC with inverter)

l Off-Grid DC system (without inverter): The DC output is immediately directed to DC loads. Excess power is stored in the battery banks controlled by the charge controller. Common applications of this system are found in RVs, boats, cabins, farm appliances, or rural telecommunication services. A backup generator may be included.

l Off-grid AC system (with inverter): An inverter is added to this system. The generated energy is directed to the inverter that converts DC to AC electricity for conventional electric appliances. Excess energy is stored in batteries and an optional backup generator can be added.

l Hybrid system: In this system, another renewable energy generator is added to generate more power. For example, the wind turbine can be added to generate electricity from wind. This system is useful in places where the weather is sunny and windless during summer but cloudy and windy during winter. This system is typically off-grid and the excess energy is stored in batteries. If neither the PV panel nor the wind turbine generates enough electricity, backup power such as a diesel generator can be added to generate the more energy.

2. Grid-tied system: with battery backup or no battery backup.

l Grid-tied system (without battery backup). In this system, the generated DC is converted to AC and used on-site. The solar power production is monitored by the solar production meter. If there is an excess energy, the energy can be fed into the electricity grid. If the PV system does not generate enough power because of higher demand, needed energy can be drawn from the grid. This process of drawing or feeding electricity to the grid is monitored by the export/import meter.

l Grid-tied with battery backup system. In this system, the converted AC is used on-site or stored in batteries. The charge controller monitors the battery capacity and excess energy is stored in the batteries for backup. If the batteries reach their full capacity, the excess energy can be fed into the electricity grid. On the other hand, if the PV system does not generate enough power, needed energy can be drawn from the grid. This process is done automatically through a net metering program.