Solar Charge Controller
The sun’s solar energy can be harnessed. The solar power cells store the solar energy as direct current in them. This direct current can be easily converted to alternating current with the aid of a special inverter called grid tie inverter. The photovoltaic cells and the grid tie inverter belong to the solar power unit of your home.
The grid tie inverter is an appliance which is specially designed to meet the needs of solar current. Another such specially designed electrical appliance is the solar charge controller.
The solar charge controller is also an essential part of the solar power unit. The primary function of a controller is to regulate charge flow in accordance to the conditions of the flow. For instance a 12 volts household utility controller will condition the charge flow to a maximum of 170 watts only and not more than that. The controllers are equipped to suspend the circuit and control the current flow in case of an excess current flow.
The two prime technologies applied by the controllers are the Pulse Wave Modulation (PWM) technology and the Maximum Power Point Tracking (MPPT) technology. A PWM controller slowly pulses down the current flow in case of an emergency. This slow pulsing enables the solar power unit to maintain a optimal flow of current, even when there is too much excess charge flow in the circuit.
The MPPT controller has a unique operating principle. It is operated by using audio frequencies of very high range (20-80KHz). A MPPT controller works by comparing the voltage output from the solar panels with that of the battery voltage. So when there is a huge gap in these two values, for example on a cloudy day, the controller helps boost up the electricity production. The grid tie inverter systems are often equipped with an in-built MPPT solar charge controller. Another advantage of the MPPT over the PWM is that, MPPT has much less wiring requirement than a PWM.
The disadvantage of MPPT is that, their working can be disrupted in the presence of a high frequency noise source. Even, the high frequency wavelengths of a radio transmitter can disrupt the working of the controller.
Another important function of a charge controller in a solar power unit is to control reverse current flow in the circuit. This happen mainly during the night when the photovoltaic cells cease to work. Apart from this charge controllers also perform additional duties of short circuit protection and lightning protection.
A household solar charge controller typically weighs between 159 to 160 gms.(0.35 lb) approximately.
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