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Wednesday, December 21, 2016

Plug In for renewable energy

An example of plug and play solar. (Photo courtesy Joshua Pearce and Michigan Tech University)

By Stefanie Sidortsova*
With additional information from Joshua Pearce
Posted Dec. 5, 2016, on Michigan Tech News
Reprinted here with permission

HOUGHTON -- A new study shows a huge US market for plug and play solar energy, with billions of dollars in retail sales and energy savings. So what's holding up widespread use?

Support for solar energy is vast. According to a 2015 Gallup poll, 79 percent of Americans want the US to put more emphasis on developing solar power. Most of the same people, unfortunately, can’t afford to install solar energy systems in their homes. Even after federal tax credits, installing solar panels to cover all of a family's electricity needs can cost tens of thousands of dollars. For others, a home solar system isn’t a consideration because they rent, or move frequently.

But Michigan Technological University’s Joshua Pearce says he knows the solution: plug and play solar.

"Plug and play systems are affordable, easy to install, and portable," says Pearce, associate professor of materials science and engineering and of electrical and computer engineering. "The average American consumer can buy and install them with no training."

In a study funded by the Conway Fellowship and published in Renewable Energy (DOI: 10.1016/j.renene.2016.11.034), Pearce and researchers Aishwarya Mundada and Emily Prehoda estimate that plug and play solar could provide 57 gigawatts of renewable energy -- enough to power the cities of New York and Detroit -- with potentially $14.3 to $71.7 billion in sales for retailers and $13 billion a year in cost savings for energy users.

Sounds great, right? Well, there’s one problem: in many parts of the United States, electrical regulations don’t allow consumers to plug and play.

Small Investment, Big Return

Plug and play solar panels connect to an ordinary electrical outlet. You’re still on the grid, but you’ve become a "prosumer" -- a consumer of energy who also produces it. The panels range in wattage and are relatively affordable, with some costing just a couple hundred dollars apiece. A prosumer can start small, with just one panel, and slowly build up over time to a system that produces 1 kilowatt of energy, the equivalent of powering 10 100-watt LED light bulbs.

The panels are also portable. So, for example, if a college student buys one 250-watt plug and play panel each year for four years, reaching 1 kilowatt of energy by senior year, that student can unplug the four panels when she graduates and take them to her next destination.

 "The technology is already there. Europeans do this all the time." Joshua Pearce

Pearce estimates that plug and play systems could generate more than four times the amount of electricity generated from all of US solar last year. 

"The vast majority of this energy never leaves the home," Pearce says. "It’s the equivalent of handling a hair dryer load. We’re talking about almost nothing on the electrical grid -- but that nothing adds up. It’s an appliance with a high rate of return."

Safe, Simple -- And Largely Prohibited

In the United States, a patchwork of local jurisdictions and regulations make it difficult to figure out if and where plug and play panels are allowed.

"You can buy the panels," Pearce says, "but you might not be able to plug them in, depending on your utility."

Pearce cites the Upper Peninsula Power Company (UPPCO) as an example of a utility that prohibits this plug and play solar use.

"UPPCO has hit their self-imposed 1 percent  limit (the minimum the state mandates they allow) for all net metering of any kind," Pearce notes. "This makes both new traditional solar photovoltaic (PV) systems and new plug and play PV systems unable to connect now unless consumers  1) use a transfer switch that can switch various home circuits from grid to the solar so if you have extra solar power, you just put more load on that system, 2) use a battery back up system, or 3) simply leave the grid. The latter is possible to do economically in this region by combining solar, a small battery bank and a cogen system (a technology that produces both electricity and heat -- usually from natural gas).

"We essentially have the highest electric rates in the country and UP customers are being blocked by financing their own less-expensive grid tied solar systems to protect a short-term utility monopoly. As grid defection becomes a progressively more profitable investment for many people in the UP, utilities that follow this short-sighted strategy risk losing significant fractions of their customer base. Our earlier analysis showed 92 percent of seasonal households and ~75 percent of year-round households are projected to meet electricity demands with lower costs using their own PV+battery+cogen systems."

In a paper published earlier this year in Solar Energy (DOI: 10.1016/j.solener.2016.06.002), Pearce, Mundada and researcher Yuenyong Nilsiam reviewed all regulations in the US that would apply to plug and play systems. They found no safety or technical issues with the equipment on the market.

"This is an area where less regulation could really help renewable energy," Pearce says. "We know that the technology is safe, and the law should reflect that."

The risk, according to Pearce, is putting too much current on one circuit, so he recommends that homeowners keep their plug and play systems to a kilowatt or less. Simple precautions make this easy -- if a panel is plugged into an outdoor outlet, for example, safety plugs on all other outdoor outlets on that circuit can prevent overload.

While some jurisdictions have recognized that there are no major safety or technical issues with plug and play panels, paperwork holds up the process. Potential prosumers often have to fill out complicated forms to fulfill utility requirements, and the paperwork and associated fees vary by utility. To simplify the process, Pearce and colleagues automated it, by writing open-source computer code that fills out every possible technical requirement. Utilities can easily use the free code on their websites.

"Some utilities have embraced plug and play, and some have ignored it because they think it’s a pittance," Pearce says. "But plug and play solar is something that can help most Americans."

Inset Photo: Joshua Pearce. (Photo courtesy Michigan Tech University)

* Editor's Note: Guest author Stefanie Sidortsova is a Science and Technology Publications writer for Michigan Tech University.

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