With so many homeowners still unclear about the potential risks associated with PV solar installations, John Burfoot reports on the lethal d.c. voltage concerns and looks at the Remote Solar Isolator™ RSIA2/ELV solar safety system, winner of the electrical industry’s Innovative Product of the Year 2012.
The Remote Solar Isolator™ design and functionality has always focused on making solar safe on any new or existing solar system. The RSIA2/ELV makes solar safe by limiting any lethal generated solar voltage to the safety of Extra Low Voltage, as per Australian Standard 3000/20071.
Many homeowners with solar panels still rely on switching off the d.c. isolator on the roof to stop the current flow to the inverter. But that doesn’t shut down the ability of the solar panels to generate lethal voltage. What if you or maintenance personnel needed access to your roof? Creating an open circuit at the inverter will only stop current flow to the fuse box, and does nothing to ensure the safety on the roof.
Joe Hudson, Inventor and CEO of Remote Solar Isolator Pty Ltd says “Electricians are putting their lives at risk, and many of them aren’t aware of the issues and problems associated with solar panels. As soon as the sun shines on the array, you’re at risk of electrocution. We need to warn both the trade and the public of this problem.”
The electrical trades union released a warning to the trade about this very issue in its National Autumn edition, promoting Remote Solar Isolator™ as the obvious solution.
JB: How can we stop the potential lethal d.c. voltages?
JH: The problem is even when the standard solar shutdown procedure is followed, such as switching off power to the inverter, lethal voltages are still being generated throughout the solar panels. The contacts in the RSIA2/ELV are specifically designed to switch off the lethal d.c. voltages contained within a solar installation by not allowing panels to combine. When installed correctly, the Remote Solar Isolator™ can be activated by flicking a switch within the fuse box, or by remotely disconnecting the incoming grid mains from the local power station. This ensures that no one is at risk of electrocution on any solar installation. This is Smart, Safe and required.
JB: What about the d.c. isolator?
JH: The d.c. isolator used on solar arrays, which is required by Australian standards, falls short of addressing this issue and is not capable to switch d.c. under full load or stop the generation of lethal d.c voltages throughout the solar array. The issue of lethal voltage generation from solar arrays still exists when this d.c. isolator is switched off.
JB: How is the RSIA2/ELV safety system different?
JH: The Remote Solar Isolator™ is different in that it is rated to switch off under full load. Water ingress is not an issue because of its special mounting system. The contacts in a RSIA2/ELV have been tested and approved to switch under full load to UL508 and VDE0435. This test ensures that the contacts can switch full load for more than 10,000 cycles.
JB: How does the RSIA2/ELV help when there is a fire?
JH: If a fire occurs on a house roof the temperature usually reaches 1500-2000 degrees. The RSIA2/ELV has an inbuilt thermal detection unit, which will stop solar panels combining when this predetermined temperature has been reached. The area is then safe for fire fighters to focus on fighting the blaze without the fear of electrocution or wasting time conducting a risk assesement.
JB: We saw cases recently with the Queensland floods, where many residents had to access the roof to escape the rising water. How can the RSIA2/ELV help these homeowners and rescue personnel during such emergencies?
JH: It is common practice in these situations for the local power station to remotely disconnect the incoming a.c. mains to affected homes. When this occurs, the RSIA2/ELV stops the solar panels from combining lethal power, making it safe for homeowners or rescue personnel to access the roof area.
Reference
1 http://infostore.saiglobal.com/store/Details.aspx?ProductID=366926
Other material
http://www.wiringrules.standards.org.au/LinkClick.aspx?fileticket=4UaAcwXiLME%3d&tabid=380
http://www.youtube.com/watch?feature=player_embedded&v=5nHemMZhuU4
