Correct cabling specification key for PV installations

Solar photovoltaic (PV) has become an increasingly popular solution for consumers who want to get off the grid or supplement grid-tied power. But faced with economic and industry challenges, contractors may be tempted to boost their bottom line by reducing costs on these projects – and cabling is an easy target.

With the current pressure felt by supply chains, contractors are stressed to meet the demands of consumers. They may turn to low-budget cables, which are not suitable for solar farm conditions such as voltage and UV exposure,” explains Svilen Voychev, managing director of Valsa Trading.

“It also sometimes happens that suppliers present contractors with cabling that looks the same as copper cabling, but is in fact copper-clad aluminium, which is noncompliant with SANS or NRCS regulations and has poor resistance and insufficient conductivity,” he continues.

The risk of fire and electrocution becomes more prominent when the wrong cables are selected. This also reduces the effectiveness of protection accessories.

UV exposure

A common point of failure in PV systems is the connections between panels. The DC connectors from the panels to the inverters can also be a pain point if the wrong cabling is used.

“People underestimate the importance of a cable’s UV rating – this plays a vital role in South Africa. A PV farm has a lifespan of more than 25 years in some cases, and the cabling has to be able to stand this test of time,” says Voychev. “Some of the cabling we stock undergoes extreme treatment to withstand radiation almost to nuclear levels. This is what contractors should be looking for if they want to offer installations that last.”

Hardy accessories make it or break it

Cable accessories are also vital in the installation to ensure that cabling is protected from damage that may lead to failure or electrical faults. “Too often, we see that installers haven’t even budgeted for accessories that could mitigate a range of problems. Something as simple as a cable tie could greatly impact the system reliability and performance, preventing cables from being sliced and worn down. But again, not just any cable tie will do. They need to be UV-rated and tested,” Voychev explains.

Voltage is also an important consideration. “High-voltage commercial installations mean that temperatures are bound to rise – and the connectors are often the first to fail in these cases. Using cheap imports that aren’t designed for these applications is sure to lead to system failure.”

Voychev recommends that contractors who are tasked with solar PV installations familiarise themselves once again with the National Regulator for Compulsory Specifications (NRCS) Act (No. 5 of 2008) and the specifications under the NRCS Electrotechnical business unit. Contractors must also ensure they comply with the latest edition of SANS 10142-1 ‘The wiring of premises'.