ABB’s plug and play string combiners for photovoltaic solar installations.

Aravind Ramachandran

ABB has developed a system that remotely monitors each string of solar modules for obstructions or even broken cables, and flags any problems found.

Solar PV modules generate electricity as long as they absorb the sun’s rays. If the sun is blocked, the panels will not produce any power.

Many things can block the sun and impair module productivity, including clouds, birds, bushes and trees, airplanes, etc., and of course, the night. Some can be removed, such as bird feces, leaves, snow or dirt, but in a utility-scale installation it is not very practical to walk around examining hundreds or even thousands of solar panels daily.

ABB has developed a simpler system that remotely monitors each string of solar modules for obstructions or even broken cables, and flags any problems found. (A string is just multiple solar panels, or modules, that have been connected together. A typical photovoltaic plant is like a direct current generator, composed of parallel strings of photovoltaic modules connected in series).

The monitors check the DC current produced by each string, comparing the output of different strings as well as their previous performance to determine efficiency, and detect where performance may be impacted by obstacles.

The monitoring device is usually installed in the string box, also called a DC switchboard, combiner or junction box. The string box is designed to protect against over-currents and over-voltages and to disconnect when faults are detected. It consists of protection products, such as fuse disconnectors with fuse links, surge protection devices and switch disconnectors.

In most utility-scale solar PV projects, string boxes are fitted with monitoring systems that perform different kinds of protection, performance and efficiency monitoring.

ABB delivers factory-assembled combiner box solutions in multiple sizes appropriate for a single string, or up to 32 strings in 1000V and 1500VDC. They are suitable for use in residential, commercial and utility scale projects, ABB combiners can also include monitoring, depending on the needs of the customer.

ABB string combiners are built with Gemini thermoplastic outdoor enclosures. These enclosures are manufactured using a thermoplastic co-injection technique that produces a material with great mechanical strength. They are available in six different sizes giving the flexibility to cover the range up to 32 strings. A robust design (IP66 – dust tight and protected against heavy seas or powerful jets of water) and high UV resistance make Gemini thermoplastic string combiners the most appropriate solution for solar installations. These combiners can be wall or floor mounted easily, depending on site conditions.

There are versions available with string monitoring solutions enhancing safety, reliability, flexibility and efficiency across the entire value chain of solar installations. Comparing and analyzing individual string currents enables precise and reliable monitoring of solar energy generation, guarantees the highest level of plant safety, and delivers the utmost protection of modules by immediately disconnecting faulty strings.

ABB’s string combiner solutions reduces downtime and increases productivity, while improving the safety of PV panels, and the entire plant.

Additional information

About the author

Aravind Ramachandran

I am the Global Segment Marketing Manager responsible for the Solar business within Electrification Products Division based in Milan, Italy. I have been active in the solar business since end of 2014 and in total have an experience of 15 years in Sales and Marketing. I like the challenges and trends in the solar industry and now I am working closely on developing a solution with string combiner for Solar PV installations. I enjoy travelling and meeting new people and exploring different cuisines. I play tennis as my favorite pastime and sport.
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