The promise of harnessing the power of the sun and turning it into renewable energy has attracted countless businesses, governments and environmental groups. But it might be a church here in Austin that ends up bringing one of the next breakthroughs in solar technology.
To understand the scope of this project, it helps to know that Saint David’s is no little roadside chapel. The Episcopal Church in downtown Austin fills up a whole city block. It provides your typical church services and then some.
“We have a coffee shop, we have a restaurant, we have a pre-school for children,” says Terry Nathan, the parish administrator. “The better part of our basement is dedicated to a homeless center." The Church keeps a staff of caterers for its side business hosting events, and has a bookstore and parking garage, which they make available for commercial use. All that takes a lot of electricity.
So about ten years ago, church members got the idea to put solar panels on the parking garage. But they didn’t take the plunge until last year. That’s when low interest rates, improved technology, and government rebates all came together.
“We had a window of opportunity that actually let us create a rather significant solar project,” says Nathan. And they were in Austin, probably one of the most progressive, solar-friendly cities in Texas.
So Nathan felt a little shock when people at the city-owned electric utility told him the project was not allowed. “I brought the Austin Energy people together and said ‘What can we do?' And basically they said, ‘Not much,'" remembers Nathan.
The problem? The church's proposal was too big, with solar production of around 150 kilowatts. In the end, church allies at City Hall convinced Austin Energy not to pull the plug. But that took some tricky engineering.
It goes back to the way cities set up electric grids in downtown areas, says Clayton Stice, a power engineer with Austin Energy. Stice says downtown networks are often separated from the rest of the city, to ensure extra protection for densely-populated, commercially-important parts of town.
"The issue this causes is that, for safety, the system is designed so that power can only flow to the customer," Stice says. "So if there is any back-feeding power, the circuit trips and opens up and cuts off power to that facility.”
The Saint David’s solar plan was so big that on days when there’s plenty of sun, but not much need for AC, it could create more electricity than the church needs. That would send electricity back to the grid, where it would register as a malfunction. It could not only cut off power to the building, but over time, damage equipment and put the downtown network at risk.
"Other cities have tried putting these larger solar systems in effect and those systems are all sized to be smaller than the annual minimum load," Stice says. "This is unique in that’s its much larger than the annual minimum load.”
The fix was to create a system that will decrease the amount of electricity produced during those days when the panels make more energy than the church needs.
Bennet Ford, an engineer on the project with contractor Meridian Solar, says it was the first time he’s worked to reduce a project’s capacity. “You never like to curtail a solar syste. That’s free energy from the sun and it’s not going to be used here on site,” Ford says.
But with these new controls in place, the project could move forward. On a recent day, Ford watched as cranes took positions at the church. He says if all goes well, the project can serve as an example not just for other buildings in downtown Austin, but in other cities.
"We’re trying to lead the way and show other utilities, we in partnership with Austin Energy, how this can be done,” Ford says.
Austin Energy says it is already getting calls from other cities. But the utility urges patience. It will take at least a couple years of monitoring Saint David’s solar power installation before the city has a clear sense of how well the system works from a technical and economic standpoint.