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April 2021

Green Energy

Photovoltaic installations: components and solutions in the BOS

Solar energy is already the most efficient energy source in many markets and is expected to be the low-cost technology of choice in many more by 2030. Despite the impact and uncertainties caused by Covid-19, photovoltaic energy is expected to expand its current market share by a seven-fold increase in capacity and potential, according to a report done by DNV. Significant solar capacity growth was recorded in 2020 in China (49 GW), USA (15 GW), Vietnam (11 GW) and Japan (5 GW).

Which are the most critical components of a Balance of System (BOS)?



It is an indispensable element in any photovoltaic installation, whether on-grid-connected or off-grid. There are two kind of inverters:

  1. string inverters, smaller inverters installed close to the PV panels
  2. central inverters, which centralize a larger number of PV panels.


Since the voltage for a single panel is too low, several panels are connected in series to provide an output voltage within the inverter’s working ratings (usually 1000-1500Vdc , with grid network output up to 800Vac).

A combiner box is composed of: Switch-Disconnector, protection against short circuits, surge arresters and, optionally, monitoring systems.


The switch disconnector must operate in accordance with the voltage, and guarantee a safe and effective load break. For short-circuit protection, fuses specific for this sector with high breaking capacity must be installed.

S7, the leading switch for photovoltaic sector

The S7 Series of Telergon is a new 2P high performance switch-disconnector capable of reaching 500 A – 1500 Vdc (750 Vdc per pole). Based on the innovative MAGIC patented technology, S7 is the result of years of research of our R&D team and the expertise provided by our successful experience being the preferred DC switch-disconnector supplier for solar plants.
  • Maximized performance
  • High safety level
  • Suitable for extreme environments
  • Compact design
  • Longer life
  • Easy to install and maintain
Modular ZFV / ZFC
Up to 65 A 1000 Vdc and 1500 Vdc
S5 / S5M / S5N

Up to 3150 A 1000 Vdc – Up to 1800 A 1500 Vdc

Manual and motorized


  S6 / S6N / S6R
Up to 630 A 1000 Vdc – Up to 500 A 1500 VdcManual and motorized
S5 / S6 Isolation only
Up to 3150 A 1500 Vdc

Telergon, leaders in specialized solutions for photovoltaic installations since 2006

Thanks to our wide experience and specialization in low voltage switchgear solutions, we have developed and manufactured specialized products in solar energy. We adapt to market trends and needs, and we are constantly researching and improving our products.

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