Solar Energy Terms Explained
MPPT (Maximum Power Point Tracking)
A technique to extract the maximum power under all conditions, from solar panels or a wind turbine.
PWM (Pulse Width Modulation)
A method to control the power delivered to a load (battery), by switching the power on and off. The shorter the power is switched on the less energy is delivered to the load.
MPPT Charge Controller
Equipment to control the charging of a battery and making use of the MPPT technique, from solar panels or wind (superior to PWM).
PWM Charge Controller
Equipment to control the charging of a battery and making use of the PWM method (cheaper than MPPT).
Converts power from solar panels or wind to power that is suitable to inject into an AC grid. If it injects power into a municipality’s grid or national grid, the inverter must be certified for the grid code of the country. South-Africa’s grid code standard is described in the NRS097 (several releases) document.
A hybrid inverter can be connected to the utility grid, usually must have a battery for operation, and usually have a built-in MPPT charge controller. These types of inverters can usually also charge a battery from the utility grid.
Hybrid Inverter without MPPT Charge Controller
A hybrid inverter without MPPT can be connected to the utility grid, usually must have a battery for operation, but without the MPPT charge controller, which can be added externally.
DC Coupled System
System coupled to solar panels (wind generator) to a battery, normally via a MPPT charge controller.
AC Coupled System
System coupled to solar panels (wind generator) to the AC Grid, normally via a grid-tie inverter.
Combination of AC and DC Coupled Systems