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Educational December 2019

Critical Infrastructure and the Rules for Resilient Lighting

It’s no secret that the U.S. electrical grid is in dire straits. Over the past several decades, energy production and consumption have risen steadily, placing an untenable burden on a system that was never intended to carry such a sizeable load. According to the American Society of Civil Engineers’ 2017 Infrastructure Report Card, the lower 48 states’ power grid—which was largely built in the 1950s and 60s— is now at full capacity, with many lines operating well beyond their design.

Combine this aging infrastructure with more severe weather events, as well as an increase of vandalism, theft and cyberattacks, and you have a surefire path to frequent and widespread power outages, damaged infrastructure and compromised public safety. During the past three decades, there has been a tenfold increase in major power outages (those affecting more than 50,000 homes or businesses), costing the U.S. economy $150 billion annually.


Fortunately, more and more cities are thinking beyond the grid to power their critical infrastructure, including street lighting. The ability of these systems to remain operational with a reliable, regular source of power in the event of grid power disruption, be it caused by climate change, vandalism or terrorism, is often referred to as “resiliency.”

Defining resiliency


Numerous sources have noted a lack of consensus when it comes to defining resiliency in the context of infrastructure. Some of this has to do with engineers, city planners, academics and others conflating resilience with reliability, or using the two terms interchangeably.


While related, reliability and resiliency are not one and the same. In the energy sector, reliability can be defined as the ability of the power system to deliver electricity in the quantity and with the quality demanded by users (source). Resiliency, by contrast is the capacity to recover and adapt in the wake of stress. The National Infrastructure Advisory Council defines resiliency as “the ability to reduce the magnitude and/or duration of disruptive events.”


According to resiliency expert Stephen Flynn, there are four essential criteria that comprise a resilient system:

  • Robustness – The ability to absorb shocks and continue to operate
  • Resourcefulness – The capacity to manage a crisis as it unfolds
  • Rapid recovery – The ability to return to normal functioning as quickly as possible
  • Adaptability – Being able to learn from experience and incorporate lessons learned to improve resilience

Applying resiliency to critical infrastructure


The Department of Homeland Security lays out 16 critical infrastructure sectors, “whose assets, systems, and networks, whether physical or virtual, are considered so vital to the United States that their incapacitation or destruction would have a debilitating effect on security, national economic security, national public health or safety, or any combination thereof.” These sectors include healthcare, communications, food and agriculture, as well as energy and transportation services.

Streetlighting might not immediately strike you as “critical” in the company of things like food and water but consider what would happen if all the streetlights in your city were to suddenly go dark. Not only would drivers and pedestrians not be able to see where they’re going, emergency vehicles would be unable to navigate safely, and theft or violence would likely increase. Considering there are an estimated 26 million streetlights in the U.S. today—the vast majority of which are connected to the grid—a widespread blackout could have a huge impact on urban mobility and safety.

If we consider streetlighting using the same criteria we use for other critical infrastructure—robustness, resourcefulness, rapid recovery and adaptability—the traditional grid-connected approach isn’t at all the ideal solution. Fortunately, stand-alone solar-powered systems, including Sol’s EverGen® M Series Solar Lighting System, offer an alternative: one that allows you to essentially create a self-sustaining “islands,” where your lights can receive power regardless of what’s happening on the grid.

Achieving resiliency in your municipal lighting projects

Even though critical infrastructure is largely defined at the federal level, its execution—and its impacts—are borne primarily by municipalities. Here’s how a solar street, trail or parking lot lighting system can help you meet the criteria for resiliency in your municipal lighting projects:

  1. Robustness – Whereas traditional streetlights are at the mercy of the grid, stand-alone solar-powered lighting is fully autonomous. If one system loses power, the problem can be diagnosed and repaired independently, while other systems retain complete functionality.
  2. Resourcefulness – When a storm hits, technicians and maintenance staff are invariably stretched thin. Solar lighting uses low voltage, meaning no specialized electricians are required, plus, because you’re able to monitor your lights remotely, you can get ahead of potential issues, reduce maintenance costs and ensure safety.
  3. Rapid recovery – It can take cities days or weeks to repair damaged lights and restore power after a severe power outage. With Sol lighting systems, diagnostics can be performed remotely to understand operational issues, and if a light does need to be replaced, it can be accomplished quickly and with limited disruption to traffic because the entire system is above-ground.
  4. Adaptability – Grid-connected lights are embedded at a location, meaning they are difficult to transplant should circumstances (e.g. erosion caused by a flood) require it. By contrast, stand-alone solar-powered systems are highly adaptable: you can move lights from one location to another and revise individual programs without disrupting your entire network.

The current grid-reliant method of powering our cities is failing. By choosing off-grid infrastructure and using an independent source of power, cities can keep their lights on and their citizens safe. And that’s what matters most.

Read more Sol articles

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