Solar Solution
Your Handbook on String Combiner Box (SCBs) and String Monitoring Box (SMBs)
When it comes to harnessing solar power, India is achieving new goals. The country has a cumulative solar capacity of 50GW. Moreover, the government expects to reach the 100GW milestone by 2022.
In the light of government subsidy programs, solar installations are becoming more common. Meanwhile, one must also understand various Photovoltaic (PV) array components. (Apart from the main solar panels!)
Let’s start with the string combiner box (SCB) and the string monitoring box (SMB).
In the light of government subsidy programs, solar installations are becoming more common. Meanwhile, one must also understand various Photovoltaic (PV) array components. (Apart from the main solar panels!)
Let’s start with the string combiner box (SCB) and the string monitoring box (SMB).
What Is a String Combiner Box (SCB)?
A typical PV array consists of many panels connected in series. The panels produce Direct current (DC) that goes into an inverter or power controller unit.
Since there will be many panels in a single PV array, there will be many wires. A string combiner box (SCB) is a significant yet straightforward device. The SCB allows a PV array to transition from multi-wire output to a single wire output.
What Goes Inside a Typical SCB?
A Typical SCB houses the following components:
Input terminals:
There are two input terminals in an SCB, and they connect to:
- A positive bus bar for the positive output strings from the solar array.
- A negative bus bar for the negative output strings from the solar array.
A Surge Protection Device (Surge Protection device):
The SPD protects the solar installation from sudden voltage spikes. It keeps the output current in check. Thus, preventing the output strings and other PV components from burning out.
A disconnector switch:
The disconnector switch is a safety cutoff device. This switch cuts off all input current in case of any malfunction or mishappening.
Output terminals:
The output terminals allow for setting up standard electrical wiring for an inverter. DC output strings from the solar panel reach the SCB. In the SCB, the strings connect to bus bars with individual fuses. Only two output wires leave the SCB, and the output wires carry the combined DC of all positive and negative strings in a PV array
Why consider SCB?
SCB makes managing every input wire easier as it has individual terminals and fuses. The fuses protect each string against over-current. Furthermore, installing an SCB ensures that a fault in one input connection will not affect the entire PV array’s output.
What Is a String Monitoring Box (SMB)?
String Monitoring Box is an electrical device that collates the electrical input from individual strings of a solar array. In addition, an SMB also allows monitoring electrical parameters of input strings such as, temperature, fuse status, SPD status, and, Disconnector switch status.
When monitoring a PV array, an SCB is an excellent choice. The device also allows hassle-free power management while offering easy detection of faulty input strings and allowing fast identification & repair.
How Are SCBs Different From SMBs?
SMBs are a step ahead of SCBs as they provide both string combiner and monitoring benefits!
SMBs check individual input strings while keeping track of the common bus voltage. While one can rely on an SCB for surge protection, adding an SMB helps with the performance of a PV installation.
The SMB helps maintain a PV arrays output by:
- Allowing real-time monitoring of individual strings.
- Tracing any DC input loss caused because of a faulty wire.
- Storing PV output data for reference and analysis.
VNT—The Home of Cutting-Edge Solar Services
Large-scale deployment of solar installations ensures a steady power generation. However, by virtue of efficiency, it is also vital that installers be able to manage and optimize PV arrays.
At VNT, our R&D team commits to creating products that assist in making the most of photovoltaic installations. We have been manufacturing industry-compliant solar equipment since 2015 and strive to create a sustainable future for all.
If you have any queries about solar products and services, write to us at info@vnt.in.
