PPL seeks more control over distributed energy resources

Solar panels are popping up everywhere, and PPL Electric Utilities says it needs more direct control over how those distributed energy resources (DER) are applied to the energy grid’s always-exacting balancing act.

The utility this month filed a tariff request with the Pennsylvania Public Utilities Commission seeking permission to exert direct control over the expanding number of DERs, such as solar, which is sprouting up on residential and commercial rooftops and which involves customers selling electricity into the grid.

The sun-generated electricity is a key to transitioning to cleaner forms of energy, but, as always, the devil is in the details. The petition filed by PPL Sept. 9 maintained that the burgeoning number of DERs coming online could create a level of chaos when it comes to the task of keeping the grid in balance. “As the deployment of DERs continues to increase, it will become critically important for the Company (PPL) to monitor and manage the DERs interconnected with its electric-distribution system,” the utility said in its petition.

Keeping supply and demand in perfect balance is increasingly difficult as generation shifts from a static number of major utility-owned power plants to also include a fleet of hundreds of small DERs. The output of those DERs depends on the whims of the sun, which also complicates the job of the grid operators.

PPL told the PUC in the documents that the developing situation was creating blind spots known as “load masking” in its data flow caused by solar panels that may or may not be sending electricity to the grid at any given time, and that an increased ability to not only monitor DERs, but also control their output was vital to maintaining grid stability. Either that, or the number of DERs connected to the grid will have to be limited unless ratepayers were willing to finance a major upgrade of the grid’s capacity.

“Given PPL Electric’s current inability to directly communicate and manage customer DERs to leverage grid support functionality, the amount of intermittent generation that can be interconnected must be limited in order to maintain system stability and reliability,” PPL said.

While still early in the approval process, there have been no particular objections filed to PPL’s assertion that it needs a firm hand at the controls. There is, however, a difference of opinion on PPL’s strategy of asserting “direct control” over DERs.

Moreover, PPL is now before the PUC seeking permission to have its DER customers install the “advanced inverter” and communications equipment that will enable its technicians to provide day-to-day control over DERs. The company last year struck a deal with GE to develop just such a system.

But the proposal did raise questions on a couple of points. The Natural Resources Defense Council and Sunrun, the nation’s largest residential solar-power energy services firm, asked the PUC why the utility required direct control over DERs when there were widely used inverters that currently can do the job autonomously. PPL responded that it would add a layer of safety that would prevent the unintended energizing of a powerline taken down for repairs of maintenance.

Sunrun also raised an objection to the idea of the PUC ruling only on PPL’s inverter plan rather than holding off until a statewide inverter standard for all of Pennsylvania’s utilities is decided upon. The company formally asked the PUC in late September to shelve PPL’s petition in favor of a statewide review.

Currently, Sunrun is the only solar company to have formally objected to PPL’s plan, but its response said the entire industry was closely watching the case before the PUC.