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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, June 01, 2021 03:06 PM
Hobby Circuits List
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Solar Circuits |
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Ideal Diode for PV Solar Panels
designed
by David Johnson -- March 1, 2011 |
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Solar panels usually include a diode at their outputs. The
diode prevents current from back feeding into the panel at night from the battery
being charged by the panel. |
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Most photovoltaic solar panels are used to charge a battery during the daytime.
Nearly all panels come equipped with a blocking diode. The diode prevents DC
current from flowing backwards from the battery bank into the panel at night.
The usual blocking device of choice is a schottky diode with a typical 0.5v voltage
drop. In some large panels, which can often source over 4 Amps of current, the
power loses due to this voltage drop can add up. As an example a 4KW solar
power system made of 20 200 watt panels will dissipate some 40 watts of power in the
diodes. The circuit below uses a new high voltage ideal diode IC from Linear
Technology. The LTC4357 contains all the circuitry needed to control an
external n-channel FET. The circuit shown below performs a standard diode
function with a much lower 0.06 voltage drop at 4 Amps. When current tries to
flow in the other direction, the IC turns off the FET, blocking the current.
The LTC4357
contains a charge pump circuit to provide the needed gate-source voltage for the
n-channel device. An n-channel is used since they tend to have much lower
channel resistances and higher voltages than p-channel parts. The 100v device
picked has an on resistance of only 0.015 ohms. The circuit is good for over
10 Amps but I would recommend that the FET be mounted to a heat sink if the current
exceeds 8 Amps. |
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Click on Circuit Below to view PDF of Schematic |
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