Introduction

Solar PV systems typically have multiple strings of solar panels that need to be combined before being connected to a charge controller or an inverter. Combiner boxes – using a range of pre-assembled switchgear – are typically used for undertaking it.

General Description

Connecting solar panels in series forms a string of solar panel. The string voltage could reach up to 1500Vdc. Protecting individual strings from short circuits is extremely important. Also, as solar panels are exposed to potential voltage spikes due to thundershowers, surge-protection devices (SPD) is used to earth these unwanted voltage surges. One point isolation for servicing the system is also incorporated in a combiner box.

String Protection

DC fused string protection devices with finger-safe fuse holders are used in the combiner boxes to provide protection against possible short-circuits in PV strings. Fuses disconnect the faulty string immediately (and reliably) thereby protecting the system from potential fire hazards, arising from excessive heating of cables from excessive currents.

Surge Protection

Unwanted surge voltages due to lightning could propagate into the connected devices like charge controllers and inverters if not rightly mitigated. Surge Protection devices, responding to only surges in voltages, are devices that divert these voltages spikes to earth, thereby protecting critical and expensive devices connected to the solar panels.

Remote Monitoring and Control

The main output has no-break functionality. The MultiPlus-II takes over the supply to the connected loads in the event of a grid failure or when shore/generator power is disconnected. This happens so fast (less than 20 milliseconds) that computers and other electronic equipment will continue to operate without disruption.

DC ISOLATOR

Disconnecting the solar system is often required for maintenance, inspection or even in case of PV system failure – to avoid further shutdowns in the electrical network. DC isolation switch assures complete disconnection means for solar system before it enters the solar components.