Thursday, June 13, 2024

Solar Breaker Reference Design

The solution for single-phase residential solar installations is designed for operation under high temperatures and includes advanced power monitoring and fault detection capabilities.

Solar breaker

Solar breakers and components of solar power systems ensure safety and efficiency. As protective devices, these circuit breakers protect against electrical overloads and short circuits, preventing damage to equipment and fire hazards. Solar breakers also isolate photovoltaic panels for maintenance or emergencies, supporting operational control and compliance with electrical regulations. Solar breakers optimise performance and extend the lifespan of solar installations by mitigating risks such as arc faults and maintaining system integrity. Microchip has introduced the Residential Solar Breaker Reference Design, utilising the HV9901 to provide a reference solution for single-phase residential solar installations. 

Components of the design, including the HV9901, have a temperature tolerance of up to 125°C. This rating ensures the durability of these systems when operating in high-temperature environments typical of solar panels. The design incorporates the MCP39F511A for energy tracking, which facilitates power monitoring and offers benefits such as fault monitoring. This feature detects issues with inverters or panels that could lead to hazardous conditions and provides alerts for performance drops. Additional safety and robustness are supplied by the optional integration of the MCP9701, which helps manage system performance under extreme temperature conditions, such as disconnecting the inverter from the load during over-temperature events.

The design combines two functionalities: the HV9901 as a relay driver to connect or disconnect the solar inverter from the grid and the MCP39F511A to monitor real-time power—both active and reactive—output from the inverter. Power monitoring is executed using the Power Monitor Utility software, which connects to the board via USB for data measurement. This software supports system calibration and monitoring, featuring an automated calibration process that allows for quick and efficient calibration of power metres.

The application features include protecting solar microinverters from fluctuations in grid voltages through a relay disconnect mechanism. Additionally, it offers reliability and operation at high temperatures, as it is designed to be mounted under solar panels where conditions are typically harsher due to elevated temperatures.

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The Reference Design features include an input voltage range of 195 Vac to 264Vac and an RMS current capacity of up to 15A through the relay. It incorporates an external relay for connect/disconnect signals and input power measurement capabilities. Additionally, the design uses optically isolated digital signals for control and status updates.

The design offers benefits, including the ability to withstand harsh conditions and provide a long operating life, which is suitable for environments typical of solar panel installations. It facilitates shorter design cycles and reduces the need for multiple prototyping spins, enhancing development efficiency. Moreover, the solution is compact and robust, making it suitable for fitting under solar panels, optimising space, and ensuring durability.

Microchip has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.

Nidhi Agarwal
Nidhi Agarwal
Nidhi Agarwal is a journalist at EFY. She is an Electronics and Communication Engineer with over five years of academic experience. Her expertise lies in working with development boards and IoT cloud. She enjoys writing as it enables her to share her knowledge and insights related to electronics, with like-minded techies.


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