Originally published in The Weekly Packet, March 16, 2023
Analysis: Is grid capacity a viable concern?
SolAmerica’s project has raised the question
by Maggie White
Recent community engagement on the subject of the proposed solar facility that SolAmerica, an Atlanta-based company, is seeking to construct in Blue Hill has brought “the grid” into everyday conversation. National and state-wide coverage regarding green energy incentives and government initiatives have added to the charged topic (pun intended).
At its most basic, the grid—or power grid—is the infrastructure that allows for electricity to safely reach homes and businesses. As with other taken-for-granted aspects of modern life, it’s not necessary to understand how the grid works in order to benefit from its existence. However, when it comes to how much space is available for grid connectivity, some foundational knowledge could help to clarify how a project such as SolAmerica’s will affect the availability of local grid space.
The grid is a three-part network that allows for various kinds of energy to be converted into electrical energy and, in turn, for that electrical energy to be distributed to homes and businesses. According to Judy Long, Versant Power company’s communications manager, the grid is “America’s most complicated machine” and comprises generation, transmission and distribution. These components work in tandem with one another, using substations, to ensure that energy is being safely conducted (i.e., at the right voltage).
At Versant, they don’t make power, meaning that they are not involved in the generation part of the process. Instead, Versant transports power through the transmission system—recognizable as overhead power lines connected by poles or through buried underground wires, all carrying high voltages—and the distribution system (smaller lines that deliver safe voltages to homes, businesses, etc.).
To further clarify, Rick Reardon, Department Chair of Electrical Programs at Eastern Maine Community College, said that the power grid is analogous to U.S. road systems, where transmission lines carrying higher voltages are akin to interstate highways/national routes and distribution lines carrying lower voltages represent the more localized roadways.
The whole process requires substations, which is where the voltage is decreased, or “stepped down,” as Long puts it. The work within the substation relies on various equipment, including transformers.
“A typical distribution substation is comprised of a high voltage circuit breaker to protect the…transformer, the transformer which steps the voltage down, a distribution bus and circuit breakers connected to this bus to protect the multiple branch circuits (aka local roads) that are fed from the substation,” said Reardon.
Can a grid reach capacity?
When it comes to what a local grid can accommodate, location matters, according to Long. “Versant Power builds and maintains its transmission and distribution equipment to handle the amount of load that is expected in a certain area,” she said, adding that studies are conducted as to localized needs and then equipment is “right-sized” accordingly.
Long cited New York City as an example of a place with equipment designed to handle a lot of energy and, on the other end of the energy spectrum, a small town such as Blue Hill. It’s not that the grid will run out of space, necessarily, but that existing equipment has the capacity for only so much connectivity.
“Because the electrical equipment in [the Blue Hill] area was designed and built before the demand to interconnect to the distribution system increased exponentially, some areas may need a lot of work to safely accommodate increased power flows while maintaining voltage control and keeping service reliable,” said Long in an email.
That can be costly and—as will be explained in the next section—issues arise when power supply exceeds demand.
How are alternative energy sources (i.e., solar, wind, etc.) affecting the grid?
By nature (literally) wind and solar have greater variations in their output than do other energy sources. This complicates things because maintaining and building the grid requires that voltage remains stable, that power is reliably being transported and that supply meets demand, according to Long.
“Connection of any additional generation to the grid creates significant challenges for managing grid voltage, frequency and reliability. The intermittent nature of wind and solar creates extreme challenges for protection and control of the grid. Unlike the fuel tank in your car or your home, there is no storage for electrical energy. Electrical energy is used as it is created,” said Reardon, who added that existing equipment and control systems cannot adapt to these changing conditions, and protections and control systems therefore must be upgraded.
“In some cases, alternative energy projects seeking to connect to the grid would be of such a volume that there is not enough customer demand or use on the circuit to absorb all the excess power exported to the grid,” said Long, who referenced recent local and national incentives for green energy that have resulted in larger projects looking to connect, thus causing delays in connectivity. “The distribution system was not built for connections of this size and quantity,” she said.
How would a solar project like the one SolAmerica is proposing affect local grid space?
Long said that SolAmerica’s project would be considered medium-sized at 2 megawatts. Of Blue Hill, Long said that the “capacity at that substation is in excess of 5 MW.” SolAmerica would therefore be using about 40 percent of existing substation capacity.
Taking that into consideration, Reardon said that there would still be “enough room for over 400…home systems. That is a very unlikely number of installations in such a small community.” Home systems, Reardon estimates, require about 7 kilowatts (a kilowatt is 0.001 of a megawatt).
However, there are still safety and reliability concerns to consider. “We have to make sure that as people are exporting energy onto the distribution system, it does not compromise the safety and distribution to the neighbors. If a solar system is pumping out a lot of energy, we need to ensure the voltage on the line does not surge, that it stays even,” said Long. This requires upgrades.
When a solar project is approved, who is responsible for grid updates, if needed, to ensure the grid can handle the energy generated?
“Those who want to connect to the distribution system and potentially export energy are responsible for paying for any upgrades needed to accommodate their project,” said Long.
Upgrades include adding more protective equipment, upgrading the electrical wire or electric conductor and making upgrades to a substation. Long added that upgrades can be “prohibitively expensive” for the customer and that, moving forward due to demand, “projects are likely to confront more and more costs to connect.”
As it pertains to SolAmerica, the company’s vice president, Tony Yonnone, said at a recent Blue Hill planning board meeting that SolAmerica would be spending $1.7M on equipment upgrades to be paid to Versant. According to Yonnone, “The upgrades are required to safely interconnect our project, but they will also increase the capacity of the circuit to which we’re interconnecting.”
Long confirmed her belief that these SolAmerica updates will be a benefit. “There will be improvements to a line that could use some improvements.”
Once upgrades for a given project have been made, is the project taking away “grid space” from other residents and businesses in the town?
It’s not that people and projects cannot or will never be able to connect, but it is, again, a matter of time and money.
“There are some cases where we have several projects requesting to connect, and after some or all projects are connected, we may not be able to connect more resources without making substantial upgrades to the distribution system or the substation,” said Long.
Will SolAmerica’s updates benefit others in town?
While quantifiable data as to how many homes or how many customers, etc. could potentially benefit from SolAmerica’s $1.7M upgrades was not something Long, Reardon or Yonnone could offer, Long did confirm that there will be increased capacity.
“The latest information from the team that does these studies—and this is complicated engineering—is that the upgrades needed on the distribution line will not only provide benefits enabling the [SolAmerica] project to connect, but will also benefit other people on that particular stretch of distribution line. This is not always that case.”
What is off-grid?
When people make a conscious choice to go “off-grid,” what this means is that they are disconnecting from the national system that distributes power to homes and businesses and may be using something like a solar battery to convert the energy without the usage of the grid. (There are also people who live off-grid not by choice but because of their particular economic or physical circumstances.) The installation of solar panels does not equate to going off-grid because the energy generated from those panels still needs to be connected to the grid in order to convert that solar energy into electrical power.
Note that the above information pertains to the matter of the grid only: there have been other concerns raised by the community about larger solar projects, including environmental impacts and disturbances.