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Tackling Solar Power Challenges

Issue 5 and Volume 9.

Energy independence and saving money are on most people’s minds these days. To this end, they are looking at different options to power their homes, with one of the most popular being the addition of solar panels (typically on the roof of the dwelling). In a number of cases, utility companies and local governments are offering grants or other financing arrangements to encourage residents and businesses to install solar and other alternative energy sources. In some areas, utility companies are even installing solar panels on telephone/electric poles throughout their service area.

I have seen extensive use of housing solar panels on at least one military base, and in my first due we’re seeing half a dozen or more solar installations each year. According to the Solar Energy Industries Association, “A solar project will be installed, on average, every 4 minutes in the U.S.”1 Solar panels are becoming more sophisticated, and are even being designed to integrate into walls or roof shingles. Not only is solar power here to stay, but it will continue to grow significantly.

Note: The NFPA developed an extensive report called “Firefighter Safety and Emergency Response for Solar Power Systems,” and the report serves as a background reference for much of the material in this column. Although solar panels can be found in a number of different locations, this column will focus on their use on buildings, particularly residences.

Panel Challenges

Solar panels on a building present several challenges to firefighters. One challenge is that they present an energized electrical service on the roof that is not easily shut down. They also present electrical hazards to firefighters working on the roof, as well as in the building, while at the same time presenting a potential ignition source.

A second challenge is that the panels can significantly inhibit firefighters from performing vertical ventilation, both by limiting the space where the roof can be vented and potentially restricting safe access to specific vent points on the roof.

The solar panels also add an additional dead load to the roof that may not have been considered in the original building design, and could contribute to an early collapse if the roof structure is exposed to fire. However the NFPA report does indicate that the additional load is spread across a relatively wide area, reducing the potential impact.

The report also identifies the possibility of biting/stinging insects nesting in/around the solar panel equipment. There is also the possibility of a medical emergency involving electrocution via the solar panel system that will require a fire department response. Each of these challenges can be significant and provide for potentially unknown variables during a fire response.

Cutting Power

To effectively manage residences and buildings equipped with these systems, firefighters must understand some basics about solar power, as well as understand the specifics of the systems that are installed in their coverage area. You can’t expect success if you wait until you pull up at an incident to figure out the systems.

As the NFPA report indicates, “A critical task during fireground operations at any building fire is to shut down the utilities, including the electrical utilities to remove the electrical shock hazard.”2 Not only does shutting down the power remove the shock hazard, but it can also eliminate the “heat” from an arcing electrical power source that may contribute to a fire’s ignition and continued combustion; it’s possible that shutting the power off may even cause a fire to be extinguished. Having confidence that the electrical power is shut down is important for all firefighters. The problem with a solar installation is that the power shutoff process may not be obvious or simple, taking away that confidence needed for a successful fire attack. Throw in backup batteries, and/or an emergency generator, and the power shutdown process becomes that much more complex.

Probably the biggest concern is the inability to “de-energize” the solar panels when they are exposed to sunlight. You can shut down the disconnects provided to the home or business itself (you should insist that these be installed in all systems), but you cannot shut down the panels themselves or the wiring coming from them. You must treat them as energized and handle a fire involving them like you would other electrical fires. Do not break the panels or cut wiring coming from them.

If you can realistically cover the panels with something that will completely block light then you can stop the power generation, but this is easier said than done. The NFPA’s report mentions that wind and hose streams are two things that could inhibit the possibility of covering the panels, besides the fact that the paneled area could easily be large enough that it can’t be covered with available salvage covers. Another concern: Even at night, apparatus scene lighting could generate enough light to power the panels, creating an electrical shock hazard. Scene lighting will not normally be powerful enough to sustain an arcing fault or a heat ignition source from the solar arrays, but it can provide enough light to have the solar array present a shock hazard.

Shut down every possible disconnect for the system, remembering that this only stops power from the solar system from connecting into the system. Street, battery, generator or another form of power could all still keep the electrical system energized. Firefighters must be familiar with shutdown procedures for all of these systems as it is likely that the public utility service company most of us rely on to control power at an incident may not be familiar with, or will possibly refuse to get involved in, shutting down private systems that aren’t directly related to their electrical service.

Roof Ventilation

When faced with a building with solar panels that needs to be ventilated, if at all possible, do so in an area removed from the solar panels. Panels are normally located on the south-facing side of a peaked roof, so it is quite possible that 50% or more of a roof may not have panels on it and can be ventilated like a normal roof.

A question arises regarding whether a roof ladder can be effectively deployed on a roof with solar panels. While one side of the roof may be free of panels, the hooks for a roof ladder used for safety would need to be placed on the far side of the peaked roof. Our firefighters have requested that solar panels not be located within one foot of the roof’s peak to address this issue. Note: If the roof ladder is aluminum and an electrical conductor, using them near electrical equipment such as solar panels could create a conductive path to the firefighter. Avoiding contact between ladders and solar panels is important.

The NFPA’s report suggests firefighters consider using positive pressure ventilation (PPV) in dwellings equipped with solar panels, but there are some tactical situations in which the use of PPV might not be a suitable alternative. Use caution when conducting roof ventilation to avoid coming into contact with or damaging the panels, and be aware that they present a trip and slip hazard.

Shared Information

To effectively work around these systems, firefighters must first and foremost know that they are there. In a perfect world, all new installations are preplanned in a documented system and shared with all members of the department during the construction/development process. Don’t just assume you’ll be able to pull up at a residence and determine that solar power is being used. Panels may not be visible from the street if a home faces to the north. If you’re not getting preplanned information about solar installations, the 360-degree size up that should be done at all incidents becomes even more critical—but even then, at night or in smoke it’s easy to miss panels on the roof.

Once the presence of a solar system has been identified, the locations of the disconnects are critical. These may or may not be easily found, and there is no standard way of identifying them unless you have already worked this out in your fire district. This information will be critical to your size up of a fire incident.

We have a local resident installing a 10 kW direct current (DC) photovoltaic system on one side of the peaked roof of his home, with 44 panels along with a sealed lead-acid battery system going in his basement. The maximum voltage supplied by the system will be 150 volts DC power, and the home already has a residential sprinkler system. He is an expert on solar power, is making his home independent from the power grid and has provided the following process to the fire department to assist in disconnecting the power should there be an incident at his residence: 1) Go to side D on the ground floor and turn both disconnects to the off position, 2) remove AC power to the house, 3) turn both DC disconnects on side D of the lower roof and the disconnect on side B of the upper roof to the OFF position to remove DC power from the house.

There is then an additional procedure to disconnect the batteries in the basement of the home. If these steps are followed, power should be disconnected to the house, although there still is the possibility of an electrical fire involving equipment in the basement which may require additional action to remove power.

We’re fortunate that he is working with us from the get-go, and has provided drawings and diagrams that we can load into our preplan program to make available in the field should there ever be an incident at his residence. In addition, the homeowner has provided an emergency transfer switch that directs utility power to the house or backup power to the house from the battery-based solar system. This switch has been located outdoors, adjacent to the electric meter, and is accessible to the fire department. This switch is equipped with a middle “off” position that can be locked in that position to disconnect the house from either system, a feature not normally required but that does play an important role for the fire department.

Know the Facts

I can’t emphasize enough the importance of working with your building officials to get upfront information on solar system installations in your district. We must understand and assess potential electrical shock hazards and arc flash hazards, as well as methods to mitigate such risks in the field before they are encountered during an emergency.

Refresh your emergency procedures for dealing with emergencies involving batteries of various kinds, which you may find at telephone switching stations, data centers and other facilities with critical power needs. The potential exists for small explosions and battery acid spills. No matter what, locate and utilize individuals in your department and/or community with expertise in power systems who can respond to these emergencies to provide technical guidance. You may need to stand by and stand back from certain situations if you cannot safely manage them, and that is a tough thing to do.

Firefighters must remember that not only is solar power becoming more common, but do-it-yourself kits can be purchased at home improvement stores, which will lead to installations of various quality. Get out and look at the systems going up in your district to better understand how they work and what procedures to follow when they are involved in an emergency. Preplan these buildings and share the preplans with all your members/shifts as well as mutual aid agencies. It’s clear that not only are these systems here to stay, but they will continue to become more complex and require us to increase our training and sophistication to deal with emergencies involving them.

Note: This article was written in collaboration with Douglas B. Williams, P.E., of Wycombe, Pa., an engineer with specific expertise in solar power systems.

Reference

1. Solar Market Insight Report 2013 Q2. Solar Energy Industries Association. Retrieved on February 14, 2014, from www.seia.org/research-resources/solar-market-insight-report-2013-q2.

2. Grant C. (10/2013) Fire Fighter Safety and Response for Solar Power Systems. National Fire Protection Association. Retrieved on February 14, 2014, from www.nfpa.org/research/fire-protection-research-foundation/reports-and-proceedings/for-emergency-responders/fireground-operations/fire-fighter-safety-and-response-for-solar-power-systems.