What PV System?
WHAT SOLAR PV SYSTEM IS RIGHT FOR ME?
Design Approach and Overview of typical PV Configurations
The design approach followed by AWPower engineers is to provide a modular, flexible and phased approach towards providing a long-term solar PV solution. The solutions described in the above infographics for AWPower’s office facilities consist of a combination of the following four typical configurations:
Grid-Tied Feed-In PV Systems. These systems have PV panels that are connected directly to an inverter. The electricity it generates is used locally on the property. Excess generated electricity is fed back into the electricity grid.
Grid-tied PV Systems with Reverse Power Blocking provide electricity to the property when there is a demand for it, but blocks any excess electricity generated from feeding back into the grid.
Grid-tied systems will cease to generate electricity when the sun is down. Also, when the grid is down (like during load shedding) the system will be shut down by nature of its design to comply with anti-islanding rules (a safety feature). A feature of grid-tied inverters is, for example when the load is 50kW and the PV generation at that moment is 40kW, the system will draw the balance of 10kW from the grid. A grid-tied system has no batteries.
A Grid-tied system will primarily reduce costs, whereas a Battery-tied system will primarily provide energy security, and secondarily reduce costs.
Battery-tied PV Systems usually have batteries and a charge controller (AC or DC coupled) to supply inverted power to essential load circuits when the grid is down (e.g. during load shedding) or when there is no generation from PV (e.g. when the sun is down). Such systems are normally wired through sub-distribution boards that would support that circuit when the grid is down. It is also possible to the support the full load through such a system. Battery-tied systems can function as Grid-tied (Hybrid) or Off-grid systems.
Battery backup systems are similar to the Battery-tied PV systems but excludes the PV modules which may be added later.
Generators can be used in conjunction with Grid-tied PV Systems. If the generator feeds into the main DB with a transfer switch (manual or automatic) the PV System can be wired into the DB after this switch. When the grid fails and the switch transfers power from grid-supply to generator supply the generator can effectively “simulate” the grid to allow for the Grid-tied PV system to continue producing power. A separate control system, that recognises that the supply is now coming from a generator, is required to prevent the PV System from feeding power back to the generator and damaging the generator. It is also a requirement that the size of the PV system does not exceed the generator size. The ratio of PV power to Generator power is also dependant on the brand of inverter, generator and controller. When a solar PV system is deployed in conjunction with a generator, it can result in significant savings in generator fuel costs.