When things go wrong with current isolation methods

Understanding the Safety Issue

Whenever the sun is shining, solar PV panels combine to generate lethal DC voltages that simply cannot be turned off.

The existing isolation system employed on most rooftop solar installations does nothing to stop the panels from combining and producing lethal DC voltages throughout the array.
The placement of a DC switch/isolator, as shown in figure 1 (whether placed on the roof, next to the inverter or both), will still allow the generation of lethal accumulated DC voltage throughout the panels and associated wiring, highlighted in red. As a consequence, these installations are a continual source of danger for maintenance and emergencies, including fire throughout the world.

When a Solar Safety ShutOFF is incorporated into your solar installation and turned off absolutely no combining of lethal DC Voltage occurs. The Solar Safety ShutOFF may be operated at the switchboard or as remote as the local substation. This feature is advantageous in a storm, flood, bushfire or even maintaining the electricity grid (stopping back feeding inverters)

When things go wrong with current isolation methods

To provide sufficient energy from solar panels to inverters with minimum losses increased voltages have been required for the generation of solar installations. For the Australian domestic market, a cap of 600VDC was introduced. Unfortunately, all forms of isolation have focussed on switching the combined output of the panels leaving the issue of lethal DC potential throughout the entire solar installation, even when all isolators are off. Because a solar array continues to combine panels and generate electricity whenever the sun is shining, all components are subject to continuous DC potential. If damaged, this solar generator may cause instant combustion at any point in the solar installation. More alarming is that in many cases the Fire Brigade have needed to implement extra precautions to extinguish roof fires where solar panels are installed – for fear they may receive a lethal electric shock – whether the panels were the cause of the fire or not.

Unprotected solar arrays accumulate and produce lethal levels of DC voltage increasing risk to homeowners, emergency service personnel and anyone accessing the roof area for general maintenance of the solar panels or roof area (cleaning gutters etc).

Damaged panels, wiring, inverters or dc isolators can cause fire due to the continuous power feed from solar panels.

UL Report Findings
Some findings provided by Underwriters Laboratories:
* Turning off an array is not as simple as opening a disconnect switch. Unlike a typical electrical or gas utility, on a PV array, there is no single point of disconnect.
* Tarps offer varying degrees of effectiveness to interrupt the generation of power from a PV array. Also, firefighting foam should not be relied upon to block light.
* PV systems are capable of producing electrical power sufficient to cause a lock-on hazard.
* Severely damaged PV arrays are capable of producing hazardous conditions ranging from perception to electrocution. Damage to the array may result in the creation of new and unexpected circuit paths.
* Damage to modules from tools may result in both electrical and fire hazards.
* Severing of conductors in both metal and plastic conduit results in electrical and fire hazards. Care must be exercised during ventilation and overhaul.

For more information please read UL Report findings: PV-FF_SafetyFinalReport.pdf

The Solution to rooftop solar panel fires

The Solar Safety ShutOFF may be added to any new or existing solar installation and provides true safety for any solar installation. The Solar Safety ShutOFF can be installed on homes, farm sheds, schools and commercial buildings and can be easily operated by home owners, emergency services personnel, tradespeople and roof maintenance personnel.
When the Solar Safety ShutOFF is fitted to your home, anyone may stop the generation of electricity of the solar panels simply by following the standard solar shutdown procedure located at the meter box. In an emergency, when access to the meter box is limited the entire solar array may be deactivated, removing all lethal DC voltages just by disconnecting the incoming power at the house, the street or the nearest substation. This then provides a SAFE environment for all emergency personnel, tradespeople and you to access the solar PV system and roof knowing that NO lethal DC voltages are being generated anywhere in your solar installation including the solar panels and associated wiring.

The Solar Safety ShutOFF is the first step in resolving the safety issues accompanied with solar installations by providing the only air gap solution to shutting down an entire solar installation just by disconnecting the incoming grid supply. Solar Safety ShutOFF provides the:
* Ability to switch off any solar generator both locally and remotely, providing a safe environment for anyone accessing a roof.
* Does not place operator at risk if solar array is damaged or the roof is electrified.
* Utilises the latest air gap isolation technologies providing up to 4mm air gap in less than 5 milliseconds.
* Provides true module level shut down isolation.
* When shut off, it leaves zero DC voltage circulating anywhere in system.
* Ability to clearly indicate safe solar panel isolation via existing inverter.
* Ability to switch off when a predetermined temperature has been reached (if heat is detected from an internal or external fire the entire system will safely shut down).
* Ability to shut down solar generation independent from the solar panels.
* Prevents solar panels back feeding into the electricity grid.
* Allows emergency services an immediate and unrestricted path to attack a fire or emergency situation rather than lose precious time performing risk assessments or not be willing to go on the roof due to increased risk of electric shock.
* Electricians would be able to work on the array and change faulty components knowing that NO lethal voltage can be generated.
* Anyone would have safe access to work on or just near the array without fear of finding themselves in a hazardous situation caused by an unknown fault or damage to the array.
* Prevents potential for electric shock when cleaning solar panels.
* Is compatible with Arc Detection Units which can provide 24/7 Safety monitoring and control.
* Can be installed on any new or existing system.
* Cost effective and safe.

For more information visit www.remotesolarisolator.com

Remote Solar Isolator is the most technologically advanced safety system available for solar generation

Remote Solar Isolator

The Remote Solar Isolator is the most technologically advanced safety system available for solar generation.

The Remote Solar Isolator is designed to integrate seamlessly into any solar array without affecting its performance or appearance. It splits strings of solar panels to the safety of Extra Low Voltage removing lethal d.c. voltages generated by both domestic and commercial solar installations. This is of utmost importance during an emergency and is recommended by the latest Australian Standards as a safe procedure for maintenance.

The Remote Solar Isolator has been tested and fully complies with Australian / New Zealand Standards (AS/NZ 3100:2009 ; AS/NZ 61000.6.3:2007 C-Tick mark) and exceeds the latest NEC 690.12 safety specifications by providing instant module level shutdown capability.

* Provides a single source solution that exceeds requirements for compliance of NEC 690.12.

* Uses the latest air gap isolation techniques providing up to 8mm air gap in less than 5 milliseconds
Provides true instantaneous module level shut down isolation.

* Removes lethal d.c. Voltages on any solar array providing a safe environment for all

* Automatically shuts down if it detects heat from a fire
Prevents solar panels back feeding into the grid.

* Allows emergency services an immediate and unrestricted path to attack a fire or emergency situation rather than lose precious time performing risk assessments or not be willing to go on the roof from concern of electric shock.

* Electricians would be able to work on the array and change faulty solar panels or cables knowing that NO dangerous or lethal voltage can be generated.

* Anyone would have safe access to work on or just near the array without fear of finding themselves in a hazardous situation caused by a hidden or unknown fault or damage to the array.

* Prevents potential for electric shock when cleaning solar panels with water.

When an Remote Solar Isolator is fitted to your home, anyone may stop the generation of electricity of the solar panels simply by following the standard solar shutdown procedure. In an emergency, when access to the meter box is limited the entire solar array may be deactivated and reduced to Extra Low Voltage just by disconnecting the incoming power at the house, the street or the nearest substation. This then provides a SAFE environment for all emergency personnel, tradespeople and you to access the solar PV system and roof knowing that NO lethal voltages are being generated anywhere in your solar installation including all wiring between the panels.

For more information please visit our website remotesolarisolator.com

Safety switch for your roof – a lesson in hindsight

By John Burfoot

Remember the days before the safety switch became compulsory to install in new homes? At the time, we just relied on several standard circuit breakers in the fuse box to keep us safe. Provided we didn’t accidentally electrocute ourselves, it was a bullet we could easily dodge, and a price we didn’t have to pay. Or was it?

Before long, and after a string of tragic deaths, the safety switch became a mandatory safety device to prevent accidental electrocution. And it has since proven to be very successful in saving lives – I know, because it recently saved mine!

The reality is that no one plans to give themselves a potentially lethal electric shock when carrying out a home remedy on the extension cord, or on the outdoor light that ‘just’ needs a couple of wires connected to the mains. Even ‘just’ changing a light bulb has served up plenty of unsuspecting jolts over the years.

Nowadays, the decision to install a safety switch for the home fuse box has become a ‘no-brainer’. However, a new problem has recently emerged. Many homeowners are at risk to an additional lethal Voltage electrical power supply in their home – the solar array on their roof.

In fact, the average domestic solar installation can supply up to 600 volts d.c. That’s enough power to deliver a lethal electric shock. And since a solar array can never be turned off while the sun is shining, homeowners are at risk when they access the roof area. Think of all those homeowners who were rescued from their roofs during the recent Queensland floods.

Solar panels have also been reported to cause roof fires. More alarming is that in many cases the Fire Brigade have needed to implement extra precautions to extinguish roof fires where solar panels are installed – for fear they may receive a lethal electric shock – whether the panels were the cause of the fire or not.

And yet, many homeowners (and solar installers) still have not learnt their lesson of hindsight from the safety switch genesis...

“I’m careful, it won’t happen to me.”
“When do I need to get on the roof?”
“I won’t be affected by floods.”
“It’s not worth spending the money.”
“I can always call the Fire Brigade if there’s a fire on the roof.”
“My solar installer says it’s already safe.”

Already safe? The current method of switching off the d.c. isolator in an emergency does not shut down the ability of the solar panels to generate lethal Voltage. This only stops current flow to the inverter, and does nothing to ensure the safety on the roof.

Fortunately, there is now a safety switch for a solar array known as a Remote Solar Isolator™ (RSI). When an RSI is correctly fitted to a new or existing solar installation the homeowner can easily de-activate the array from combining its power and reduce it to the safety of Extra Low Voltage. This enables the homeowner to safely work near the array or the solar wiring from the roof. It also allows emergency personnel to gain safe access to your roof area.

For added control and safety, the RSI can be remotely activated from the local power station by disconnecting the incoming a.c. mains to the home. This may be particularly useful during flood emergencies, since homeowners would not be placing themselves or emergency personnel at further risk by gaining access to the roof area to escape rising water.

The RSI also comes fitted with a thermal detector in case of fire, which will stop the solar panels combining when a predetermined temperature is reached. This makes the roof area safe for fire fighters to focus on fighting the blaze, without fear of electrocution.

One thing becomes certain. Complacency around electrical safety levels is like a game of Russian roulette. It will only be a matter of time before a life is lost as a result of a solar array electrocution. Let us learn the lessons of the past to anticipate the pitfalls of the future, and eliminate those areas of risk we actually do have control over.

Like the safety switch for your home, the Remote Solar Isolator™ is a safety switch for your solar installation on your roof, and an inexpensive solution for those unexpected events.

Aussie invention the solution to potential risks associated with PV solar

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