Advanced component technology plays a crucial role in improving the efficiency and reliability of solar energy equipment. Solar panels require high-performance components such as microinverters, power optimizers, and monitoring systems to maximize energy output and ensure safe operation. By integrating advanced components with solar energy equipment, engineers can improve energy efficiency, reduce operational costs, and extend the lifespan of solar systems.

As more energy equipment manufacturers compete for market share, they pay close attention to the features and specifications of specialized switching, protection, and filtering components that handle high currents and voltages in energy equipment. This blog article highlights the importance of safe operation, long lifetime, and superior performance regarding the preferred components for these crucial functions in solar inverters and ESS.

The PV inverter comes in various shapes and sizes, from residential rooftop installations to vast solar farms. One exciting development is the decentralized string inverter arrangement in large solar arrays. Traditionally, the output from these arrays was fed into a single, centralized inverter, in which a contactor was often used to cut off power to its AC side. To increase the inverter's efficiency, solar system operators are now implementing a distributed topology, replacing a single central inverter with as many as three smaller string inverters, each rated for less than 100 kW.

After energy from the sun is converted to AC electrical power by the inverter, what is not used instantly may be diverted to the grid or stored in an ESS. The ESS option is becoming increasingly popular for householders as it increases independence from the grid and can reduce total energy costs in the long term. At the grid scale, deploying ESS installations provides part of the answer to the intermittency of solar and wind renewable energy sources.

Developing reliable ESS equipment requires careful attention to safety and circuit protection due to the high voltages and currents passing between the inverter, the ESS, and end-use equipment. In the US, the National Electric Code standard NEC2014 690.12 requires an emergency cut-off device controlled by a relay to be installed near a solar panel array to protect the safety of first responders in an emergency.

The HE-V Series Relay is ideal for this application since it can cut off both positive and negative lines on the DC side of the inverter. The Relay ensures safe operation as it dissipates electrical arcs generated by switching operations upwards along the insulated walls of the Relay using a blow-out magnet mechanism and serial contact connection. The Relay's low coil holding power of 210 mW also helps to reduce fire risk by minimizing system power consumption. The 3.8 mm contact gap and large creepage and clearance distances provide for compliance with IEC regulations governing the rapid shutdown application.

Safety cut-off Relays are also used in the battery system. When a large inverter supplies the battery, a smoothing capacitor on the input side prevents voltage fluctuations when a large load is connected to the AC side. The large size of this Capacitor results in a high inrush current, which can lead to contact welding in the safety relay; for safety relay applications with a risk of contact welding, Panasonic supplies special Relays that include built-in contact welding detection capability. The HE-S and HE-R Series miniature Relays feature an auxiliary 1FormB contact to create a safety circuit.
 

The battery ESS requires further safety functions. If the battery's insulation deteriorates, a ground fault might occur, which can be dangerous to people nearby or could result in equipment damage. A Panasonic PhotoMOS Semiconductor Relay responds to a ground-fault current by switching on a current sensor that can provide a fault signal to the control unit. A second use of a PhotoMOS Semiconductor Relay is monitoring the charging voltages of a group of battery cells. Voltage monitoring is an essential battery management system (BMS) function. A PhotoMOS device offers the advantages of small size, unlimited switching cycles for a long operating lifetime, and high-quality products for robust performance and a long operating lifetime.

The solar energy applications described in this article demand the ability to maintain safe operation in a high-voltage, high-current environment while offering the equipment manufacturer the advantages of reliability and long lifetime. Panasonic products have a long track record of superior performance and reliability resulting from innovative design, advanced production techniques, and high-quality materials. The film capacitors and relays highlighted in this article are consistent with this track record and promise high-reliability characteristics such as humidity resistance in film capacitors and long cycle life in relays.