Stand-alone system configurations
There are many different possible designs and configurations for stand-alone off-grid PV systems. The focus of this design project is on small-scale systems, which will serve to constrain the number of designs that will be explored here. It is worth noting that the possible designs increases greatly as system size and complexity increases. Small-scale stand-alone systems can be divided into three main categories based upon the loads that they power: DC only, AC and DC, and AC only. The most appropriate out of these designs will be determined by the energy needs and particular loads of the project.
The three-line wiring diagrams presented below and in the rest of this design process omit certain components as they are are not installed with all systems and adding them would add additional complexity to the wiring diagram. The following components should be considered for incorporation into any off-grid system:
- Ground fault protection device (GFPD)
- Residual current device (RCD) or ground fault current interruptor (GFCI)
- Shunt
- Charge controller temperature sensor
- Low voltage disconnect
- DC-DC converter
