by James Hynes
Solar energy technology has been making inroads in central Pa.
As the soft morning fog lifts off a 30-acre field in Drumore Township in Lancaster County, the bluish glass veneer of 20,000 solar panels glistens in the sun. The Keystone Solar Project, built by the Community Energy Solar Company on a former poultry farm off Route 272, was connected to the grid in October 2012 in front of a crowd of over two hundred local residents.
The solar farm is the largest in the Eastern U.S., using a technology called photovoltaics (photo = light; voltaic = electricity) to generate enough clean solar electricity to fully power about 950 houses each year. Day-to-day power is distributed among 4,200 homes on the grid.
The $20 million project was funded, in part, by a grant from the Pennsylvania Energy Development Authority and the sale of energy credits to institutions such as Juniata College, the Clean Air Council and the Philadelphia Phillies baseball franchise.
In the Bald Eagle Area School District in Centre County, about half the electricity for the middle school, high school and the Wingate Elementary School buildings is supplied by solar photovoltaic (PV) panels.
In nearby Bellefonte, three school buildings are also powered, in part, by solar panels.
According to Ken Beane, director of fiscal affairs at Bellefonte Area School District, the district partnered with Smart Energy Capital to install the system. Smart Energy—with a state grant of $2.2 million—funded and owns the installation. The private firm sells power to distributors as well as to the Bellefonte School District at a discount.
Between thin packs of melting snow on the roof the State College Friends School’s modest ranch building, one can see the swath of dark shiny PV panels that supply enough electricity to power about half of the school’s large community room.
Dan Hendey, head of the school, said that the 3.6 kilowatt system was installed in 2004, and has since supplied about 5 percent of the school’s total electricity needs. The installation came at a $30,000 price tag, but through a cost-share agreement offered at the time by West Penn Power, the Friends School paid $5,000. The school is also eligible for carbon credits each year from the state of Pennsylvania (Dan Hendey isn’t certain which agency issues the credits, but the Pennsylvania Farm Bureau in partnership with Global Emissions Exchange has such a carbon credit trade program in Centre County).
“We calculate that it saves us about $250 a year,” said Hendey, “so this annual amount accompanied with credit payments that we have already received has made up for our share of the project.”
Four years ago, Phil and Karen Yanak had a solar water heater installed in their Milheim home. Two years later, they had a 5,200 watt photovoltaic system installed to supply their house with electricity.
“In the winter, we use more electricity than we produce,” said Phil Yanak. “And vice versa in the summer.”
The Yanaks have not only paid for their system through reduced energy bills, they’ve generated a net surplus of electricity.
“So far the panels have produced more electricity than we have used,” Yanak added.
As the effects of particle pollutants and carbon-related climate change become more apparent, an increasing number of energy consumers are making the investment in clean, renewable energy sources. In Pennsylvania, the most popular of these sources is PV solar panels.
Experiences vary among those who’ve opted to invest in PV modules. The cost, return on investment and efficiency of panels depends on a number of factors: the type of module, the installation company, the size and location of a building or home, the positioning of a pitched roof (south facing panels capture the most sunlight) and the extent to which other energy-saving measures have been taken in a building.
But there’s no question that, while Pennsylvania is focused on prospects of natural gas and the process of hydro-fracking, technologies for renewable energy—particularly solar—are slowly but surely taking hold above the Marcellus Shale.
“Solar PV has to be the most suitable [renewable energy source] for the central Pa. climate,” said Ed Johnstonbaugh, Extension Educator of Renewable Energy & Energy Savings at Penn State Cooperative Extension in Westmoreland. “Because of the scalability, ease of utility interconnection, improving cost competitiveness [and] immediate impact, PV has to be the renewable energy source for the masses.”
Most homes and businesses with renewable energy generating systems are grid-tied. That is, they remain connected to the standard grid where power is still largely generated by coal, oil, natural gas and nuclear power plants.
When a customer generates on-site electricity through wind, solar, geothermal (drawing heat from deep underground) or biomass (such as corn ethanol or energy-producing microbes), any surplus electricity enters the grid and the customer is given kWh (kilowatt hour) credits equal to that amount of power. Then when PV panels generate too little electricity, the customer uses electricity from the grid, and the kWh credits from the surplus are issued to the customer in the subsequent bill. This process is called net-metering. A net-meter measures electricity that flows in and out of a home or building.
West Penn Power, a subsidiary of First Energy Corporation, provides electricity for several counties in Pa., including Centre County. According to spokesman Todd Meyers, there are 329 net-meters in West Penn’s service region, generating about 4 megawatts of electricity—enough to power one thousand homes for a year.
“Of the 329 net-meters in use,” Meyers said, “38 are commercial, 287 are residential, and 4 are industrial.” Solar energy accounts for 293 of those net-meter sources.
Jason Grottini, manager of operations at Envinity, a local employee-owned company that specializes in green design, home energy audits, construction and energy efficiency, says that his company has installed over 75 PV and solar installations throughout Pennsylvania.
“Contrary to popular belief,” Grottini said, “we receive plenty of solar radiation to power photovoltaic panels for home and commercial use.”
According to David Gantz, renewable energy specialist at Envinity, local and regional utility companies have been helpful partners in the slow transition toward renewables.
“These utilities are required by law…to use energy from renewable sources,” said Gantz. “It’s in their best interest to aid homeowners to turn towards renewable energy.”
In November 2004, Pennsylvania passed the Alternative Energy Portfolio Standard (AEPS) which requires that retail utility companies supply 18 percent of their electricity from “alternative” energy sources by 2020. These sources include renewables such as wind, geo-thermal, biomass and solar photovoltaics, but may also include coalmine methane (a natural by-product of coal) and coal gasification (a process by which coal is processed from a solid into a cleaner burning gas), although it’s not clear if natural gas hydro-fracking could be considered a qualifying technology. There is a mandated minimum of 0.5 percent photovoltaics by 2021.
“We need a mix of energy sources,” said Scott Surgeoner, a spokesman for First Energy (West Penn Power’s parent company). “A piece of that has to be solar.
“We’ll continue to support renewable sources. But in the final analysis, it’s a personal choice. Potential consumers should fully research the costs of installing a system as well as incentives to help defray some of those costs.”
How Solar Photovoltaic Technology Works
To understand how PV works, it’s important to understand a little about how atoms work. A typical photovoltaic panel comprises two layers of crystalline silicon semi-conductors made up, of course, of silicon atoms.
Each silicon atom contains fourteen electrons, situated among three concentric “shells” or orbitals. Though a silicon atom has only four electrons in its outer orbital, it has a natural tendency to acquire eight. Thus, two atoms with four outer electrons will share them so that both atoms can have a total of eight outer electrons among them. It is this joining together of electron-sharing atoms that creates material bonds and forms a silicon sheet.
Tight pairings of atoms is what gives pure crystalline structures strength, but it also makes them poor conductors. This is because most of the electrons are effectively “locked” into place. To improve conductivity, manufacturers treat the silicon semi-conductor layer so that one layer is positive and the other is negative. This is done by adding impurities to the silicon in a process called “doping.” One silicon layer (the negative-charged one) is treated with phosphorus, which adds an extra “free” electron to the silicon atoms. The other layer (the positive-charged one) is treated with boron that removes an outer electron, effectively creating a “hole.” This process creates an electrical field where the free electrons in the negative layer move to fill the holes in the positive layer.
Free electrons move to fill holes until the electrical field becomes neutral. It remains neutral until more energy is added to the mix. In the case of photovoltaic panels, the infusion of energy comes from photons—particles of light energy from the sun. When photons enter the PV panels, they knock electrons loose from the silicon atoms, setting back into motion the movement of free electrons. This movement of free electrons creates a current that passes over contacts and enters the building’s circuits.
Since solar energy doesn’t require burning, PV power generation is carbon neutral and produces no particle pollutants. Unlike nuclear energy, solar doesn’t pose the problem of where and how to store long-lasting radioactive waste materials. However, PV does feature certain inefficiencies and costs that challenge its readiness for a mass market.
According to the U.S. Department of Energy, about 55 percent of the original sunlight that makes contact with a PV system is lost. There are several reasons for this. First, as mentioned above, while crystalline silicon is effective at converting solar energy into electrical energy, it’s not a good electrical conductor. Even when the two layers are treated crystalline silicon has a high level of internal resistance, which leads to energy loss.
To mitigate energy loss, some manufacturers install metal contact grids on panels in order to decrease the distance that electrons must travel before entering a building’s circuits. However, a contact grid installed over PV panels blocks some of the photons from being absorbed by the panels in the first place.
Furthermore, PV systems, ironically, work best in low temperatures, so manufacturers and installers must manage optimizing direct sunlight while keeping the system cool.
Another factor leading to inefficiency is variability in what is called band gap energy. The sun’s photons travel in light waves of different lengths and at different frequencies, thus containing different levels of energy.
Each panel has an electrical field with a band gap—that is, a window within which solar energy can be converted into electrical energy. Some photons have too little energy for a given band gap, while some have too much energy. Only the energy that falls within the band gap (the band gap energy) is converted into useful electrical energy. A low band gap would be open to more levels of energy, making it more efficient. However, materials with low band gaps tend to have weak voltage (weak electrical fields). Thus, the challenge for researchers is to find or develop a material that has both a low band gap and strong voltage.
When coal, oil or natural gas is wasted, it represents a permanent reduction in that energy source. This isn’t so with sunlight since it’s renewable.
But inefficiency in a solar system means that more panels must be used to effectively capture sufficient sunlight to power a home, farm or business. Using more panels requires more finite materials such as silicon, glass or contact metals along with the fossil energy used to mine and produce those materials.
PV systems require considerable parts and material to be even minimally effective. For example, because silicon is reflective, it must be coated with an anti-reflective chemical. Manufacturers also cover panels with strong glass to protect them from rain, snow, hail and wind. Furthermore, the electrical charge that enters the building’s circuits is direct current (DC), and it must be inverted to alternate current (AC) to be useful. Hence, costly inverters must be added to the system, either built in to the PV modules themselves or somewhere in the house.
Since sunlight isn’t constant, solar energy must be stored in batteries, exchanged for power from a standard grid or both. For anyone seeking to be entirely off the power grid, a deep-cycle lead-acid or nickel cadmium battery and a charge controller to regulate battery charge are necessary—and expensive (together nearly $900 according to EnergyBible.com). Add to this the extra wiring, grounding equipment, mounting hardware, junction boxes, breakers, cable kits and assorted other equipment, and you’ve got a significant upfront investment.
According to estimates by EnergyBible.com, a typical grid-tied PV system built to produce 3,168 watts costs nearly $25,000 to install. A typical off-grid system costs around $28,000 to install.
Researchers are presently studying ways to increase efficiency in PV technology by capturing more sunlight and reducing energy loss. One option is the use of multi-junction cells. These entail stacking several silicon layers in a way that creates multiple electrical fields with multiple band gaps. Multiple band gaps would open the “window” for a wider range of photon energy levels.
Another option is increasing surface area of the PV cell. This may entail using textured rather than smooth panels or forgoing flat panels altogether.
In 2009, a team of Penn State students competed in the Solar Decathlon home-design contest where they introduced their Natural Fusion solar home featuring solar rods instead of conventional panels. The 360 degree shaped rods were designed to absorb more direct sunlight as the sun “moves” across the sky during the course of the day.
Envinity’s Dave Gantz argues that, in spite of the hefty price tag, PV panels are a worth it.
“Despite the initial high install cost,” he said, “many people don’t realize just how strong of an investment solar is.” He points to “annual rate of returns…in the 5-10 percent range” even without state and federal incentives. This means that a residential PV system would take ten years to pay for itself. To the average home or small business owner, this may seem like a long time to see a return on investment.
“Solar should be viewed as a long term investment,” Gantz said, “and is most applicable for those who know they will be in their home for years.”
“For those planning on only being in their homes for a short time,” he added, “solar can be viewed as a strategy to increase resale value, but there really is not a defined real estate process to communicate this value.”
He also points out that while designers continue to make advances in solar technology, “what we have now is reliable and can generate 30 years of electricity.” He added, “If it takes a homeowner 10 years to pay back a system, [they] will then be locking into 20 years of free electricity.”
Costs for PV installation have declined sharply over the last decade. According to the website Sustainablebusiness.com, nationwide prices for modules have dropped an average 5-7 percent a year, with an 11-14 percent reduction in 2011 and 3-7 percent for the first half of 2012 (the last available numbers).
“The cost of solar panels has decreased significantly in the last few years, but electricity rates continue to rise,” Gantz said. “As this trend continues, solar energy will only become more affordable.”
Gantz estimates an annual electricity rate increase of at least 3 percent for homeowners in Central Pa. However, he adds that since Pa.’s utilities have become deregulated, “it will be difficult to predict trending rate increases for some time.”
He contends that, like most technology, costs will continue to fall as demand rises. He compares PV systems to microwaves and VHS camcorders which have become far less expensive over the last thirty years.
“Solar is in the same boat,” he said. “It used to be a niche market, but as it gains in popularity and general acceptance, costs will continue to decrease.”
PV systems “provide owners with a hedge against escalating energy costs,” said Ed Johnstonbaugh of Penn State Extension. “These systems are scalable,” he added, “so customers can size a system to meet their needs and pocketbook.”
Johnstonbaugh also points out the benefit of PV energy being distributed-generation power. That is, its power generated at the point of consumption. This means that either solar energy consumers can be self-sufficient or, in grid-tied systems, “their presence on the grid lowers the system operating overhead for all electric consumers. That affects everyone’s bottom line.”
According to the website of Sun Directed, “for people with time-of-use [net] metering, you make the most [solar] electricity when electricity is the most expensive. It’s like making your own gas to drive up a hill and buying it when you are going down.”
Some incentives are available. The Energy Policy Act of 2005 established a 30 percent tax credit for residential installations of renewable energy technologies including wind, geothermal heat pumps, fuel cells, solar water heaters and photovoltaic panels. The tax credit applies to modules, labor and related equipment for residential PV systems place in s