There are many risks associated with the installation of solar PV, but knowing what hazards you need to avoid should ensure a safe install. Fluke is highlighting three of the top electrical hazards you need to avoid when installing and maintaining solar PV installations.
Solar installations in the UK are growing at an impressive rate, with the number installed having doubled within the last year, while there’s an expectation that it will double again by 2030.
With such rapid expansion, technicians will need to search for ways to reduce their risks. This includes being vigilant on site, but there are also tools available, such as the newly announced Fluke 393 FC, that can ensure accurate measurements to avoid any accidents.
In PV applications current is ‘wild’ and not limited by electronics, therefore choosing the correct solar testing equipment is vital if workers – and the PV system itself – are to be protected against a range of potential electrical hazards.
The top three hazards are:
Shock or electrocution from energised conductors can happen when current takes an unintended path through a human body, with lethal results from as little as 50 mA hitting the heart.
Electrical shocks are typically caused by a faulty insulation of cables and wiring, damaged insulation of safety covers or improper grounding. The main places such conditions exist in a PV system are the combiner box, the equipment grounding conductor, the PV source and output circuit conductors.
- Arc faults and arc flash
Electrical arc faults that spark fires are high power discharges of electricity between two or more conductors, with the discharge causing heat that can lead to the deterioration or even to burning of wiring insulation. PV systems are particularly vulnerable to arc faults caused by disruption in conductor continuity or by unexpected current between two conductors, often the result of a ground fault.
Arc flash is a phenomenon of large-scale PV arrays that have medium-to-high voltage levels. Only since large-scale solar energy systems have been created has arc flash become a DC issue, which is why arc flash hazard risk analysis must now be carried out on DC systems over 120V.
The issue is particularly prevalent when fault-checking in energised combiner boxes, where PV source circuits are used in parallel to increase current, or when carrying out checks on medium-to-high voltage switchgear and transformers.
An arc flash happens when there’s a significant level of energy available to an arc fault in DC and AC conductors. The flash emits hot gases and radiant energy that can be around 19,500°C (or four times the temperature of the surface of the sun).
The most at risk set-ups are residential inverters with input voltage up to 500V and large-scale inverters with up to 1500V. It’s essential to use a meter that’s rated for the relevant measurement category or CAT rating as well as the application’s voltage level. This is so the unit can cope with average voltage levels and high voltage spikes and transients that are capable of producing shocks or causing an arc flash.
- Switching to 1500V
Most major manufacturers of inverters and solar modules are shifting from 1000V systems to 1500V for greater efficiency. For solar installations, overvoltage category CAT III 1500V systems are being more widely used and CAT III and CAT IV equipment is essential for PV systems at high altitudes.