Everyone has spare batteries lying around. Their untapped potential is awakened only in case of emergency—when the power goes out or in a TV remote crisis—before being unceremoniously stowed away for another rainy day, left to clutter drawers until their services are needed.
Such is the life not only of the AA battery, but also of the modern solar-powered home’s backup battery or generator—a life of untapped energy. Penn State University’s newest project, the GridSTAR Center, aims to put that battery to work at all hours of the day. GridSTAR intends to show the future of intelligent power distribution and erect a LEED Platinum demonstration house for that microgrid to show visitors how it works.
Setting up in the Philadelphia Navy Yard, the project is an opportunity for the university to teach homeowners, homebuilders, and the industry at large about important technologies that will save money while contributing to the continued conservation of energy and resources. The 1,200-acre former naval shipyard has been transformed into a City of Philadelphia-owned industrial park that will serve as a national center for energy and sustainability research. In addition to the demonstration home, the site is home to the Energy Efficient Buildings Hub—one of the nation’s largest research facilities on building efficiency and economics.
The GridSTAR project is an extension of the university’s 2007 and 2009 efforts in the Solar Decathlon. Penn State kept its home from the 2007 decathlon and turned it into a laboratory and teaching facility. From there, the university built momentum, interest, and countless industry partnerships that have allowed it to garner a $125 million grant from the Department of Energy to fund this larger microgrid project. “We have the capability to build affordable, smart-grid-capable, solar-energy homes,” says David Riley, Penn State’s director of the GridSTAR Center. “We need to change the culture to inform homeowners about what they should be asking for and show them what’s possible.”
When a home is equipped for solar power, it is typically paired with a backup battery or generator; in the case of an outage, the battery can stretch out and use solar energy to survive without the grid. But unless the power goes out or the solar module’s energy store is depleted, the battery does nothing for the homeowner. Compound that with battery maintenance, and the user has a rarely used piece of equipment that requires more work than its worth. A smart grid, however, allows a homeowner or building owner to put that battery to use every day.
An active energy storage system in the smart grid is able to charge batteries when electricity is cheaper at night, then discharge during the day, minimizing the amount of expensive daytime energy one needs to purchase. The battery also helps even out power shortages and surpluses. Imagine a residential community where every home has a solar array. When the sun is shining, the array creates loads of power, but then a cluster of clouds shades the sun, dramatically dropping the amount of power being produced. Once the clouds clear, it causes another jolt of electricity in the grid. The batteries smooth out this variability while also minimizing the risk of blowing transformers that can’t handle such fluctuations.
The GridSTAR Center’s demonstration home is all-electric and has a PV array on its roof. It was constructed as a modular building.
The final source of value that these batteries hold is called demand response. Utilities sometimes struggle to meet peak demand loads when high-energy load equipment is turned off and on in factories, cities, and stadiums. GridSTAR introduces the idea of a home that is able to respond to a utility’s demands—an on-call home that the utility can either ask to charge up its battery or discharge it to help the overall aggregate variable energy demand in the community. Because utilities will pay users for this service, a homeowner’s battery no longer sits superfluously but generates revenue. The payback, admittedly, is not enormous, but it helps lower the cost barrier for a renewable energy system, which is a major goal of the GridSTAR project.
These features all bring historically expensive sustainable energy systems closer to the masses, and modular building techniques play an integral role in their large-scale deployment. “If you use a modular construction technique, the labor savings and the economies can be translated into higher quality construction, more energy-efficient wall and attic construction, and more upgraded, more efficient appliances,” Riley says, explaining that people often turn up their nose to a modular home because they think it’s some kind of manufactured, low-cost home. On the contrary, a modular construction environment actually produces the highest quality homes, he says. The home’s solar-integrated roof shingle, CertainTeed’s Apollo II, illustrates the benefits of these techniques. Solar panels are traditionally installed after the roof is complete, but this product can be installed while the roof is still flat, before it is craned onto the frame, which can lead to an 80 percent reduction in installation time and labor costs.
The all-electric demonstration home has demand-response lighting and shading systems, an electric-vehicle charger, a utility-interactive electric water heater, and a mini-split air-conditioning system, which is the most innovative of the bunch because it connects the air-conditioning system directly to the solar array, when normally, the direct current power in an array is converted to alternating current and distributed to the home before being converted back to direct current by the mini-split, an obvious inefficiency.
Riley says many of these systems have similar real-world impacts. “It’s not an experiment,” he says. “These technologies really have a lot to offer consumers and utilities.” In fact, the project’s partners have already been approached by a developer to help implement a similar technology in a 500-home community. “We’ve got a nice demonstration home, but we hope we have a market-transformation tool,” Riley says. “A big part of what people ask is, ‘Will it be an actual net-zero energy home?’” But the answer is that it still takes a sensitive and conscious occupant to pull it off. Penn State has built a smarter grid, but what it really wants to build is a smarter homeowner. In the near future, it will be time to change our batteries.
