Two most commonly used technologies in photovoltaic power plants operating sensors include resistive current shunt sensor (shunt resistor ) and current sensor for magnetic field ( Hall Effect ). As a leading supplier of shunt resistors, Microhm concentrates on the current sense applications.
 
Resistance “shunt” provide an accurate and direct measurement of the flow, but do not offer any galvanic isolation. The shunt current is the least expensive solution available today for current measurement. A shunt consists of a precision resistor ohmic value which passes a current , allowing a current proportional to the voltage and frequency falls between the terminals of the shunt resistor.

The low resistance shunt current offers good accuracy at low cost as well as a simple current measurement. When we talk about high-precision current measurement, we consider the parasitic inductance of the shunt.The inductance is typical in the order of only a few nano henry. This affects the magnitude of the impedances of the shunt at relatively high frequencies. Its effect is remarkable to reduce the power factor. Because the current is essentially a shunt resistive element, the heat generated in the resistor is proportional to the current passing through it. This heating problem makes the use of shunt not a good option for high currents. They are very low-value resistors to minimize power dissipation, low inductance value and a small reasonable tolerance to maintain an overall accuracy in the circuit.
 
There are two main types of Hall effect sensors: open- loop and close- loop. The second provides better accuracy but at a higher cost, and most of Hall effect sensors that are in energy meters uses open design to achieve lower costs ring. These sensors have excellent frequency response and are able to measure very high currents.
 
Comparison chart of both measurement methods, Shunt versus Hall effect:

 
In conclusion, shunt resistors are the more cost-effective approaches for most applications. Microhm's shunt resistors, MMS8420, MMS5930, MMS4026, MMS3920 and MMS2512 are especially appropriate for current sense usage.