Cold showers and a dead iPhone battery, inconvenient though they were in the aftermath of hurricane Sandy, were inconveniences that paled by comparison to the loss of life or home. But even three weeks after the superstorm knocked out power for 8 million people, thousands were still without electricity.

As was widely reported at the time, those with solar were not spared the outages, even if their roofs were intact and the PV system capable of producing power. If the grid goes down, the inverter will automatically shut down the system thanks to UL 1741, a safety certification for inverters.

But the 600 rooftop installations in New York City were still intact after the storm, and 281 of those were still producing power, Tria Case, director of sustainability at City University of New York (CUNY) told the PV America East conference last month.

Case estimates that the city’s PV was operating at 35% of full sunny day capacity, producing 6,500kWh of solar energy per day.

"That could have supported putting power into a battery so we could be running something at night, it could have supported sump pumps, it could have supported cell phone charging. People were running around the streets of NYC wondering where to plug in their cell phones.

"Clearly, there's an opportunity. We had systems that turned off … producing something that was lost.

In 2009, CUNY produced a report with support from the Department of Energy to look at mostly mobile and special purpose PV for emergencies, such as generators, water pumps and lighting.

"We weren't so much focused on resiliency as emergency. We were not thinking about why is it that we're putting in megawatts of solar but not thinking about what happens when the grid goes down or how to utilise that solar. We were thinking about how to utilise solar in an emergency," Case said.

After Sandy, it has now become clear that PV can become an integral part of grid resilience, she said.

Earlier this year, CUNY convened a meeting of heavy hitting US agencies – the Department of Defense, FEMA and the Department of Homeland Security – along with the National Renewable Energy Laboratory, the New York Mayor's office and utilities including Con Edison, New York Power Authority, Long Island Power Authority. SolarCity and Solar One, which provided mobile solar charging stations, were the only solar companies to attend.

Back in 2006, Case’s department could find no data on how much solar there was in NYC. Her CUNY team counted 1MW "that we were able to locate and that represented about an $8.3 million marketplace."

That figure has grown to 14MW (all rooftop) in 2012, representing a $116.6 million market, which is set to balloon under Governor Cuomo's NY Sun Initiative, which could see investments of $150 million each year for the next 10 years.

"We have an opportunity to think about how we want to use solar in the context of resiliency," Case said. "We know we've had weather, we know we've had power outages, prolonged power outages. During 2008 and the ice storm there were 230,000 people without power. In 2011, between Lee and Irene, 1.2 million customers were without power. After Sandy there were 2.1 million customers without power."

"We're investing millions of dollars into these systems on our rooftop, so how can we think more creatively when we design those systems?

"There are lots of DG solutions that are being put out into the marketplace but we haven't been thinking about them from a resilient, interconnected, dynamically controlled solution that we can utilise as a resilient technology."

Margarett Jolly, DG ombudsman, Consolidated Edison Company (ConEdison) of New York, admitted that the utility had to plan for another large weather event.

ConEdison has 3.3 million electricity accounts, 1.1 million of which were knocked out after Sandy – five times any other event in history. "It was the largest hit we've ever taken," she said. "It was something we've never seen before."

ConEdison had planned for an 11-feet surge, so substations were designed for 12.5 feet, but the flooding came in at 14ft; the sandbags around the substations ended up keeping the water in, Jolly said.

It's safe to assume that ConEdison's designs won't look the same as plans hoped for by solar companies.

"I'd like to caution developers from overpromising on technology capabilities and the costs do need to be transparent," Jolly said. "We can then move forward with more trust that we are looking for something that will really help our customers."

But Sandy offered some very powerful proof points of what is possible from PV during emergencies.

As the city of Bayonne in New Jersey went dark, the Bayonne Midtown School managed to keep the lights on thanks to some canny foresight from the education board.

Advanced Solar Products completed the 232kw system in 2008 with a back-up system that combined diesel generators with PV electricity.

"This was the first such system in the world where a large PV system worked automatically in parallel with an emergency generator," said Lyle K Rawlings, the founder of Advanced Solar Products.

When the power goes out the inverter shuts down and the generator starts; the inverter then detects the generator power and goes into a different mode where it widens the tolerance for "dirty power", explained Rawlings.

Rawlings was happy with the performance of the system in an emergency, as were the school, the emergency services and the 75 people sheltering in the gym.

"Bayonne was flooded, the power went out, it was hard to get in and out of the city, it was hard to get diesel deliveries. This system worked exactly as it was supposed to: when the power went out the solar stayed on, it backed off the generator and saved that fuel.

"Sandy created a lot of implications for the future. The fragility of the electric grid was highlighted, people were knocked back to the Stone Age almost, and it taught us lessons about how deep the need for emergency power can go."