Solintity SD26 Solar Diode Block
Solintity SD26 Solar Diode Block
Low power drop blocking diode for PV solar systems
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In our article Diodes and Solar Panels we briefly introduced the importance of the use of a blocking diode in a solar photovoltaic system to prevent stored charge in the battery being lost back through the solar panel(s) at night.
Although Schottky diodes can be used to minimise the voltage drop in the diode while the solar system is generating under the sun, the power lost in the diode is not insignificant, particularly in low voltage (e.g. 12 Volt) solar systems.
In this article we will introduce the SD26 SuperDiode from Solintity, a product which does the same job as a standard solar blocking diode, but with far lower losses.
Solintity Advanced Solar Diode Block - SD26 SuperDiode
A standard blocking diode used in a PV solar system has a couple of problems. The first problem is the power it wastes - for example, when used with a 15 Amp solar panel, a Schottky blocking diode with a voltage drop of 0.45V would lose 7 Watts of the generated power. The second problem is the heat generated in the diode itself - for example, a 20A rated Schottky diode dissipating 7 Watts of heat gets very hot potentially leading to failure of the diode or of the joints connecting it to the system.
The SD26 SuperDiode pictured above is a product designed to replicate the functionality of a conventional blocking diode without the problems mentioned above. Two solar panels or (arrays of solar panels) rated at up to 15 Amps each can be connected to the SuperDiode giving protection to a total of up to 30A or around 360 Watts of solar output.
The direction of the flow of current is detected using Hall current sensors which give negligible power drop. When the solar panel is generating, a pair of switches are closed which connect the solar panel to the battery bank via your solar charge controller enabling charging. When the current is reversed - i.e. battery is discharging through the solar panel(s) at night, the switches open disconnecting the panels from the battery. The response time to a change in current direction is just 10ms.
The graph above shows a comparison between the power loss in a typical Schottky diode and that of the Solintity SuperDiode SD26. If two 15A solar panels are connected through the SuperDiode, then at peak power output just 2 Watts would be lost in the SuperDiode compared to 14 Watts if a Schottky diode was used - a total of 12 Watts of saved power, and 12 Watts of heat avoided.
More Information
For more information about the Solintity SuperDiode SD26, click here to download and view the SD26 SuperDiode User Manual (PDF). The official website for the company can be visited here: Solintity from where the SD26 can be purchased for US$95.
Article Last Modified: 13:39, 22nd Feb 2011Comment on this Article
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