California policymakers are searching for ways to rein in the cost of expanding the state’s power grid, which is necessary to combat climate change. Experts warn they’re missing an opportunity that’s right in front of them — taking advantage of the growing number of clean energy technologies owned by utility customers.

California ended its legislative session last month unable to pass a proposed legislative package to address rising electricity rates for customers of Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric, which serve about three-quarters of the state’s residents.

Lawmakers also failed to pass several bills aimed at boosting the role battery-backed rooftop solar systems, electric vehicles, and electric heat pumps and water heaters can play in balancing the power that’s available on the grid.

Replacing fossil-fueled vehicles with EVs, and gas heating systems with heat pumps, will increase statewide electricity demand, requiring utilities to invest billions of dollars to upgrade their grids. But those same technologies can shift when they use power to avoid the handful of hours per year when demand spikes. That’s important, because the cost of building power grids is largely determined by the size of those spikes — and in turn is a core driver of California’s energy affordability crisis.

If the state can use distributed energy resources to shave a bit of demand from grid peaks, it stands to save big. One example: In an April report, consultancy Brattle Group projected that virtual power plants, which can shift when EVs and electric appliances draw from the grid or tap into customer solar and battery systems, could provide more than 15 percent of the state’s peak grid demand by 2035. That would amount to around $550 million per year in consumer savings. 

About $500 million of that would flow directly to the customers who own the devices, which could help defray the cost of buying EVs and heat pumps, two technologies that need to be rapidly adopted to meet climate goals. But because tapping into those devices would cost less than making large-scale investments, utilities — and by extension all of their customers — would save about $50 million per year by 2035, Brattle found.

“California’s affordability challenges are years in the making and are worsened by climate-driven impacts like heat waves and wildfires,” said Edson Perez, who leads trade group Advanced Energy United’s legislative and political engagement in California. ​“However, there are critical steps we can take now: optimizing our existing grid, maximizing the cost-effectiveness of essential grid upgrades, and fully leveraging available technologies like distributed energy resources.”

But as it stands, California isn’t putting the full weight of policy support behind these types of distributed energy programs.

Pilot programs have petered out, seen their budgets clawed back, or have been outright canceled. The scale of demand-side resources operating in the state has actually declined over the past decade, even as the state’s grid stresses have increased. And efforts to create statewide targets for distributed energy — like those that helped spur California’s rooftop-solar and home-battery leadership — have failed to gain traction, including a proposed bill in the state’s just-concluded legislative session.

Advocates say it’s time for the state to change that — especially since there’s an expiration date for capturing the value of DERs. Without policies to encourage utilities and customers to work together to realize the grid benefits of these technologies, utilities will simply build expensive, centralized infrastructure to meet rising electricity demand. Once that money is spent, potential savings can’t be realized, undermining the economic case for VPPs.

Unfortunately, utilities have clear incentives to discount the potential of VPPs as a money-saving tool, because they earn guaranteed rates of profit on capital investments like grid buildouts, but don’t for alternatives like VPPs. Plus, they’re held responsible for failing to keep pace with growing power demand — and are loath to rely on decentralized assets owned by customers in place of tried-and-true grid investments.

California’s VPP policy landscape

This utility reluctance may well explain why a roster of bills aimed at enlisting DERs to combat rising grid costs stalled in this year’s regular legislative session.

SB 1305 proposed requiring the California Public Utilities Commission to determine targets for utilities to ​“procure generation from cost-effective virtual power plants,” and then mandate that the utilities meet them.

Similar targets for rooftop solar and batteries have been valuable for boosting early-stage deployments in California, said Cliff Staton, head of government affairs and community relations at Renew Home, the company formed by the merger of Google Nest’s smart-thermostat energy-shifting service Nest Renew and California-based residential demand-response aggregator Ohmconnect.

“If you set the targets, you begin to provide the certainty to the industry that if you invest, there will be a return for your investment over time,” Staton said.

An early version of SB 1305 set hard percentage targets for VPP procurements by 2028 and by 2035. Those percentages were stripped from the bill later in the session, leaving the final targets up to CPUC discretion. The bill failed to clear a key legislative committee anyway.

Another bill that died in committee, AB 2891, would have expanded options for VPPs to capture the value of the peak load reductions they can provide. The legislation would have ordered the California Energy Commission to create methods for VPPs to reduce how much generation capacity each utility in the state must secure to meet peak grid demands in future years.

Only a handful of California’s community choice aggregators — the public entities that supply power to an increasing number of customers of the state’s major utilities — are using this approach today. But those CCAs have been able to start paying customers with solar and batteries for the value they can provide by reducing reliance on increasingly expensive contracts with centralized grid resources — mostly fossil-gas-fired power plants.

For more than a decade, state laws have called on the CPUC to create programs that reward customers for the energy and grid values provided by their solar panels, backup batteries, electric vehicles, and remote-controllable devices like smart thermostats and water heaters.

But these efforts have been plagued by an on-again, off-again approach from regulators and utilities. The California Energy Commission set a goal in 2023 of achieving 7 gigawatts of load flexibility from VPPs and other customer-owned resources by 2030; two of the CEC’s key contributions to that effort saw their budgets slashed this year.

Meanwhile, many of the programs launched by the CPUC over the past decade have stalled out due to overly complicated structures, or had their budgets reduced or canceled due to concerns over their cost-effectiveness.

The CPUC and the California Independent System Operator (CAISO), the entity responsible for managing California’s transmission grid and energy markets, argue that these programs have failed to perform as promised. Relying on them more would run the risk of eroding rather than improving grid reliability, they say.

But the companies engaging in these VPP programs — smart-thermostat providers like Renew Home and ecobee; solar and battery installers like sonnen, Sunrun, Sunnova, and Tesla; and demand-response providers like AutoGrid, CPower, Enel X, and Voltus — argue that overly complex and restrictive rules and compensation structures are to blame.

Adding to these challenges for would-be VPP providers is the declining value of rooftop solar. Major changes in California’s net-metering policies over the past two years have slashed the value of customer-owned solar systems, slowing the growth of the state’s leading rooftop solar market.

That’s a problem for VPP providers and advocates who see rooftop solar as an important way to help meet demand from households and businesses with EVs and heat pumps — and to charge up batteries with clean electricity that VPP programs can tap into later.

A host of bills were proposed to reset state policy to restore more value to customer-owned solar during this year’s legislative session. But only one — SB 1374, which restores compensation for schools that install solar — made it through.

California’s new rooftop solar regime does reward customers for adding batteries to store surplus solar power during the day and discharge it in evenings, when the grid faces its greatest and most costly stresses.

But solar and battery advocacy groups argue that those rewards haven’t counterbalanced the broader erosion of rooftop solar values — and that the VPP opportunities that have emerged in the state can’t yet be trusted to make up the remaining difference.

“It’s important for customers to find value in the investment they’ve made, and to help the grid and lower cost for all consumers,” said Meghan Nutting, executive vice president of government and regulatory affairs at Sunnova. ​“One of the problems with VPP programs so far is that it’s really tough to talk about that value proposition up front because programs are so short, you can’t count on them, or the funding isn’t there.”

Why grid costs and VPPs are intertwined 

At the same time, California policies that encourage people to buy other distributed energy resources — namely EVs and heat pumps — are under threat from rising electricity rates, which are eroding the benefits of switching from fossil fuels.

A controversial policy enacted this year to reduce the per-kilowatt-hour rates paid by customers of the state’s big three utilities in exchange for higher fixed costs may or may not ease that pressure. But both opponents and supporters of the policy agree that shifting the balance of fixed and variable electricity costs does little to address the underlying problems.

Programs that enlist those exact same distributed energy resources to ease grid stresses have a much clearer value proposition, on the other hand.

About half of the electricity bills of customers of California’s three big utilities is made up of fixed costs like grid investments. A majority of those investments are tied to building a grid robust enough to supply power not just for average needs, but during the few hours per year when electricity use peaks.

Those peaks are getting bigger as California’s climate goals encourage more EVs and heat pumps to come online, and the costs of dealing with that have only just begun to be built into utilities’ broader grid investment plans. A series of studies ordered by the CPUC found that adding demand from EVs and heat pumps to the grid could increase ratepayer costs by more than $50 billion by 2035 — or, depending on the approach taken, costs could be contained to less than half of that over the same timespan.

One key variable in those distinct cost forecasts is whether EVs can be programmed or incentivized to avoid charging all at once and overwhelming the grid. ​“Smart charging” programs that encourage EV owners to shift when they charge their cars could save California ratepayers tens of billions of dollars over the coming decade.

With the right policies and technologies in place, big new grid demands like EVs could actually become valuable resources for energy in their own right. SB 59, a bill that passed in this year’s legislative session after failing to make it last year, orders state agencies to study the proper role for regulation that could require automakers to enable their EVs to support ​“vehicle-to-grid” charging — sending power from EV batteries back to homes, buildings, or the grid at large.

The challenge for utilities and regulators is finding the right mix of approaches that can allow them to take advantage of EVs, heat pumps, residential solar and batteries, and other distributed resources such that they avoid either overbuilding or underbuilding the grid, said Merrian Borgeson, policy director for California climate and energy at the environmental nonprofit Natural Resources Defense Council.

“We have to be really careful with any new investment — but we do need to make new investments,” she said. ​“If we pull back too far on energizing loads like electric homes or EV trucks, we miss out on getting those loads connected.” 

California could cut utility bills with distributed energy. Why isn’t it? is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.

A major expansion of battery storage may be the most economical and environmentally beneficial way for Illinois to maintain grid reliability as it phases out fossil fuel generation, a new study finds.

The analysis was commissioned by the nonprofit Clean Grid Alliance and solar organizations as state lawmakers consider proposed incentives for private developers to build battery storage.

“The outlook is not great for bringing on major amounts of new capacity to replace the retiring capacity,” said Mark Pruitt, former head of the Illinois Power Agency and author of the study, which suggests batteries will be a more realistic path forward than a massive buildout of new generation and transmission infrastructure. 

The proposed legislation — SB 3959 and HB 5856 — would require the Illinois Power Agency to procure energy storage capacity for deployment by utilities ComEd and Ameren. Payments would be based on the difference between energy market prices and the costs of charging batteries off-peak, to ensure the storage would be profitable. The need for incentives would theoretically ratchet down over time. 

“As market prices for power go up, your incentive goes down,” Pruitt said. “The idea is to provide an incentive that bridges the gap between the cost of battery technology and the value in the market. Over time, those will equalize and level out.” 

The bills, introduced in May at the end of the legislature’s spring session, would amend existing energy law to add energy storage incentives to state policy, along with existing incentives for nuclear and renewables. 

The study noted that Illinois will need at least 8,500 new megawatts of capacity and possibly as much as 15,000 new megawatts between 2030 and 2049, with increased demand driven in part by the growth of data centers. Twenty-five data centers being proposed in Illinois would use as much energy as the state’s five nuclear plants generate, according to nuclear plant owner Exelon’s CEO Calvin Butler Jr., quoted by Bloomberg. 

The North American Electric Reliability Corporation (NERC) found in its summer and winter 2024 assessments that within MISO and PJM regional grids, Wisconsin, Michigan, Minnesota, Illinois and Indiana are all at “elevated” risk of insufficient capacity. 

“NERC, PJM, MISO and the Illinois Commerce Commission have all identified the potential for capacity shortfalls,” said Pruitt. “You do have some options for alleviating that. You can build transmission and bring in capacity from outside the state. You can maintain your current domestic generating capacity [without retiring fossil fuel plants]. You could expand your domestic generating capacity. And an independent variable is your growth rate. All these have to work together, there’s no silver bullet. We know there are major challenges on each of those fronts.” 

Gloomy numbers 

The latest PJM capacity auction results showed capacity prices increasing from $28.92/MW-Day for the 2024/25 period to $269.92/MW-Day — a nearly 10-fold increase — for the following year. That “translates into an annual cost increase of about $350 for a typical single-family household served by ComEd,” Pruitt said. “The increase in costs indicates that more capacity supply is required to meet capacity demand in the future.” 

There are many new generation projects in the queue for interconnection by MISO and PJM, but many of them drop out before ever being deployed because of unviable economics, long delays, regulatory challenges and other issues. A recent study by Lawrence Berkeley National Laboratory noted that while interconnection requests for renewables have skyrocketed since the Inflation Reduction Act, only 15% of interconnected capacity was actually completed in PJM and MISO between 2000 and 2018, and experts say similar completion rates persist. 

“This finding indicates that deploying sufficient new capacity resources to offset [fossil fuel] retirements is not likely to occur in the near term,” said Pruitt. “Just because something is planned doesn’t mean it gets built.” 

Meanwhile the state is running out of funds for the purchase of renewable energy credits (RECs) that are crucial to driving wind and solar development. The 2024 long-term renewable resources procurement plan by the IPA shows the state’s fund for renewables reaching a deficit in 2028, so that spending on RECs from renewables will have to be scaled back by as much as 60%. 

Long-distance transmission lines could bring wind energy or other electricity from out of state. But planned transmission lines have faced hurdles. The Grain Belt Express transmission line, in the works for a decade, was in August denied needed approval from an Illinois appellate court. The transmission line, proposed by Invenergy, would have brought wind power from Kansas to load centers to the east. 

“That sets it back years,” Pruitt said. “Transmission is a very long-term solution. I’m sure people are working diligently on it, but it’s five to 10 years before you get something approved and built.” 

Value proposition, solar benefits 

Pruitt’s study found that if 8,500 MW of energy storage were deployed between 2030 and 2049, Illinois customers could see up to $3 billion in savings compared to if they had to foot the bill for increased capacity without new storage. The savings would come because of lower market prices in capacity auctions, as well as investment in new transmission and generation that would be avoided. 

Pruitt found that $11 billion to $28 billion in macro-level economic benefits could also result, with blackouts avoided, reduced fossil fuel emissions and jobs and economic stimulus created. 

Pruitt’s analysis indicates that the incentives proposed in the legislation would cost $6.4 billion to customers. But the storage would result in $9.4 billion in savings compared to the status quo, hence a $3 billion overall savings between 2030 and 2049. 

“Solar is great, but solar is an intermittent resource; battery storage when paired with solar allows it to be far more reliable,” said Andrew Linhares, Central Region senior manager for the Solar Energy Industry Association. “Battery storage is not as cheap as solar, but its reliability is its hallmark. Combining the resources gives you a cheap and reliable resource.” 

“Solar and storage is this powerful tool that can help reduce costs for consumers and create new jobs and economic activity,” he continued. “I don’t believe that same picture is there for building out new natural gas resources. Anything that helps storage, helps solar and vice versa. CEJA sees these two technologies as being joined at the hip for the future, they are being seen more and more as a single resource.”

Study suggests a big role for grid battery storage as Illinois shutters its coal power plants is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.

As president and CEO of Green Mountain Power in Vermont, Mary Powell developed the first utility partnership with Tesla to attach residential Powerwall batteries to the grid, providing backup clean power for the utility when needed. Customers could earn money by essentially filling the batteries at night and dispatching them during the day, Powell explained in a 2016 interview with Energy News Network. 

Today, such arrangements are increasingly promoted by clean energy advocates, who’ve dubbed distributed grid-connected batteries — plus solar — “virtual power plants” that allow homeowners and businesses to help out utilities during times of high demand. They’re also central to Powell’s current mission as head of the nation’s largest residential solar company.

Powell left Green Mountain in 2019 after two decades with the company, and in 2021 she became CEO of Sunrun. In an interview during a recent conference near Chicago, she spoke about how the culture of her former industry can slow the pace of innovation that’s much needed to address climate, cost and reliability concerns. 

“You’re talking about a 100-plus-year-old system and way of thinking, and you compound that with the fact that utilities’ whole culture is built for ‘slow and no’ and ‘protect, preserve, defend.’ For so many years, it’s been a one-way system,” Powell said. 

Virtual power plants are a prime example of the coming change. Powell said utilities’ experience with energy efficiency in recent decades provides a look at what might be coming for such pairings of solar and storage.

“I would say energy efficiency was the disruption — the first opportunity for utilities to start to think differently about their role and their mandate. And as we know, that took like 20 years, even for the most progressive utilities, to embrace.”

Utilities can generally choose to incorporate virtual power plants into their rate structures and grid services, and state regulators and legislatures can facilitate the concept through decisions, laws and policies that create incentives and provide standards. The Illinois legislature is considering a bill that would essentially allow the agency that procures power on behalf of utilities to contract with virtual power plants.  

Green Mountain Power was an early adopter of energy storage under Powell’s leadership, and broader adoption of the technology is ramping up quickly. The U.S. Department of Energy noted in a 2023 report that, “deploying 80-160 GW of virtual power plants (VPPs) — tripling current scale — by 2030 could support rapid electrification while redirecting grid spending from peaker plants to participants and reducing overall grid costs.” 

That means utilities will have to adapt quickly, and Powell sees a significant role for private developers in that transition. Powell describes Sunrun as a “clean energy lifestyle company,” branching into technologies like smart electric panels and EV charging. 

“When you think about customers having heat pumps, when you think about them having electric vehicles, you make sure that you’re leveraging all of that in a way that’s beneficial for the grid and beneficial for the customer.”

That focus on the end users of electricity is in part a bet that utilities’ need for solar power will eventually catch up to consumer demand.

“When I went to Sunrun I said to the team, ‘We’ve got to stop wandering around trying to convince every Tom, Dick and Harry utility to utilize our resources.’ We’re doing it, we just need to scale as fast as we can. 

“Because guess what, utilities are going to hit the wall, they are hitting the wall in some parts of the country, and they don’t have the ability to meet the kind of capacity demands that are projected over the next five years. They’re going to need our resources.”

Despite that expected market demand, Powell said legislative and regulatory bodies also have a role to “nudge utilities in the right direction.” Illinois in particular, she said, provides a strong example. 

“Illinois has done an amazing job. Making sure that rooftop solar is considered as part of the RPS [Renewable Portfolio Standard] is really thoughtful policy. And I am encouraged with a lot of the conversations about how we could leverage storage more. So yeah, we’re very bullish about Illinois.”

Powell also said she has no regrets about leaving the utility sector to work at Sunrun.  

“Frankly, even the fastest-moving utility was moving a little too slow for me. We weren’t scaling as fast as I would have loved us to be able to scale. It’s awesome to work on mission-driven work that you feel is valuable for the people you serve and for the planet at the same time.”

Sunrun CEO says utilities’ ‘slow and no’ culture gets in the way of energy innovation is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.

For years, utilities have grappled with how to handle the ever-growing number of solar and battery systems trying to connect to the lower-voltage grids that deliver power to customers. That’s especially true for midsize projects like, say, a solar array that might adorn the roof of a multiunit apartment complex or a community-solar project that generates power shared by hundreds of dispersed customers.

On the one hand, utilities have eyed such projects warily, fearing that if the solar panels or batteries inject too much power onto local circuits at moments when electricity demand is low, it might cause grid instability or safety problems. As a result, utilities have thrown up barriers that have delayed or halted grid connections.

But as advocates have been pointing out for over a decade, these distributed solar and battery resources can also be enormous assets: By holding back power when the grid doesn’t need it, and then sharing their extra power during periods of high demand, they can help alleviate grid strains and lower the cost of keeping the grid running for everyone.

It’s taken California regulators, utilities and clean-energy advocates nearly four years to hash out these conflicting ideas. But in mid-March, the California Public Utilities Commission approved new interconnection rules that take into account how, with the right structures in place, solar and solar-plus-battery systems can be more help than hazard to California’s overworked grid.

“This will open up opportunities for distributed energy resources to be designed in a way that aligns with grid needs,” said Sky Stanfield, an attorney who works with the Interstate Renewable Energy Council, the nonprofit group that’s been the main proponent of the new rules. ​“It’s a long time coming to recognize that distributed energy resources are a whole lot more helpful than they’re allowed to be — and that we don’t have to spend as much to upgrade the grid as a result.”

The ​“Limited Generation Profile option” just approved by the CPUC is a complicated set of regulations that determine how solar and solar-battery systems interact with the lower-voltage grids operated by California’s CPUC-regulated utilities Pacific Gas & Electric, Southern California Edison and San Diego Gas & Electric.

Today, those utilities make a simplistic set of assumptions when they consider the potential impacts of a project on the lower-voltage grid systems that carry power from substations to homes and businesses, Stanfield said — basically, that each project is producing its peak output at the time of least electricity demand from customers.

That’s pretty much how all U.S. utilities calculate the risks of new generation connecting to their grids, she noted. But this assumption is likely to yield findings that exaggerate how likely a project is to inject too much power onto local grid circuits.

To eliminate those perceived risks, utilities have demanded that project developers pay for grid upgrades themselves or have prevented the projects from connecting at all. Since those grid upgrades can cost hundreds of thousands to millions of dollars and take years to complete, the result either way tends to stop projects in their tracks.

Allowing new solar and battery projects to support the grid

The CPUC’s new policy takes a different tack, one well suited to larger-scale projects that are more likely to trigger grid upgrades. It will allow solar and battery projects to modulate how much power they send to the grid with the help of either solar inverters whose power-control systems can reduce power output from moment to moment or batteries that can soak up excess solar power and inject it back into the grid later.

Limited Generation Profile projects would be able to use these capabilities to alter their grid injections during different periods of the day, based on a set of schedules they can choose from. Those scheduling options are derived from the grid data available in the maps of hosting capacity from Pacific Gas & Electric, Southern California Edison and San Diego Gas & Electric. (Here’s a snapshot of PG&E’s hosting-capacity map for a downtown section of the central California city of Bakersfield, with circuit capacity represented in red, orange, yellow and green.)

Most utilities in the U.S. haven’t been ordered by regulators to collect the detailed and accurate local grid data needed to create these kinds of maps, Stanfield noted. In fact, the Interstate Renewable Energy Council has played a key watchdog role in alerting the CPUC to problems with these maps as they’ve been developed over the past decade, as well as in making them more useful for customers and project developers looking for good spots to connect to the grid.

Thanks to those improvements, California’s maps now contain accurate information on the hour-by-hour capacity of individual circuits.

With this data in hand, California’s three largest utilities and clean-energy project developers can finally agree on just how much power solar and battery projects can safely inject onto the grid during different periods of the day and night across each month of the year.

That amount may be close to zero during some stretches — say, on a circuit with many homes with rooftop solar systems during sunny and mild spring daylight hours, when self-generated solar power can exceed customer demand for electricity. Within those hours, Limited Generation Profile projects may export little or no energy at all.

But these ​“minimum-loading” conditions are relatively rare — and at other moments, that same grid circuit may be hungry for all the power it can get. That’s typically during hot summer and autumn evenings, when the state’s ample solar resources are fading away, yet electricity demand for air conditioning remains high — the same conditions that have caused statewide grid emergencies in recent years.

California’s power grid is struggling to deal with the wide swings between times when it has too much solar and times when all available resources still don’t provide enough electricity. In fact, the CPUC and state policymakers have made significant efforts to address this imbalance via state rooftop solar policy — which has reduced the value of solar delivered to the grid while promoting the value of batteries that can store power for when it’s needed — and with utility-scale power procurement policies, which have put gigawatts of batteries into operation over the past few years to store solar power for those evening hours when demand exceeds supply.

But until now, utility interconnection policy ​“has not taken into account, or enabled, distributed energy resources to differentiate when they produce power and when they don’t,” Stanfield said. That’s left interconnection policy misaligned with broader state policy imperatives for how best to use solar systems and batteries, she added.

It’s also put interconnection policy at odds with policy efforts to better manage growing distribution-grid costs, Stanfield noted. Pacific Gas & Electric, Southern California Edison and San Diego Gas & Electric are facing tens of billions of dollars of additional grid investment in the coming decades to supply the millions of electric vehicles, heat pumps and electric appliances that the state is asking consumers to adopt in order to reduce carbon emissions.

“Grid upgrades are expensive,” Stanfield said, ​“and we want to avoid them where we don’t need them” — particularly in cases where new solar and battery systems could actually help reduce grid strains.

Even more fundamentally, rules that bar more solar and battery power from reaching the grid based on outdated and inaccurate methods of determining their grid impacts will rob customers at large of the value those projects could provide.

That’s the conclusion reached by Amin Younes, an electric distribution planning and policy engineer with CPUC’s Public Advocates Office, which represents utility customers’ interests. Younes studied the potential for the Limited Generation Profile option to add more clean energy to California’s grids during hours when energy is in short supply.

This graphic from a presentation of his work indicates how widely the capacity of a typical distribution grid circuit can vary from hour to hour. In this case, limiting a solar or battery project to the minimum loading condition — the red line on the chart — would have forced a project to be sized to deliver no more than 1.5 megawatts of power of maximum capacity. But during many more hours of the year, that circuit could accept far more than that — often more than twice that minimum limit, or more than 3 megawatts of power.

According to his analysis, factoring in that extra capacity across the distribution circuits of all three utilities could add up to tens of billions of dollars per year in additional clean energy that could be delivered. And because that power would supply the grid at hours when electricity costs and threats of grid emergencies are the highest, that ​“could lower costs and increase grid reliability,” he said in an interview.

Finally, implementing the Limited Generation Profile option should allow solar and battery developers to avoid having to pay for grid upgrades and give them a much faster interconnection process, Stanfield said. And, if it works as planned, it could be a useful model for other states to follow.

Solving grid-interconnection challenges across the country

In a 2021 blog post, the Electric Power Research Institute, a nonprofit power-sector research group involved in a wide variety of utility technology projects, highlighted the need for more flexible interconnection policies across the U.S. to prevent the tens of billions of dollars of forecasted investment in EV charging, distributed solar and battery backup systems from being stalled out by grid constraints.

The conservative, expect-the-worst approach that most utilities take with interconnection processes may be a way to maintain grid reliability, the institute noted. But it can also ​“lower customer satisfaction and slow progress toward renewable energy targets.”

It’s important to distinguish the problems plaguing this class of clean energy from the similar but distinct issues blocking hundreds of gigawatts of utility-scale wind and solar farms from connecting to transmission grids across the country. The Interstate Renewable Energy Council’s work in California and other states has focused mainly on distribution grid interconnection policies, which cover everything from rooftop solar systems and home battery and EV charging installations to multi-megawatt solar and battery projects.

While these types of interconnection problems can stymie even smaller-scale home rooftop solar systems, the bigger challenges tend to arise with larger-scale installations like community-solar systems that generate power for many different customers (in California, for example, most projects under 1 megawatt in generation capacity aren’t responsible for paying for grid upgrades). In many states, growing grid-upgrade costs and maddeningly slow interconnection timelines have become increasingly significant roadblocks to connecting these mid-sized projects.

In Minnesota, solar and consumer groups are fighting a utility policy that can assign hundreds of thousands of dollars in grid-upgrade costs to relatively small rooftop solar and community ​“solar garden” projects. In the community-solar-rich state of Massachusetts, some developers are stuck waiting for years for grid studies to allow projects to move forward. 

States including New York, Minnesota and Massachusetts have begun to explore flexible interconnection policies — the more general term for the approach California is taking, according to Stanfield — but only through pilot projects or laborious ​“non-wires solutions” programs run by utilities. They have yet to embrace a standard way for clean energy developers to work with utilities.

Most other U.S. utilities haven’t been compelled by state law and regulatory mandates to produce the detailed distribution-grid-level data collection and hosting capacity analyses that enable the CPUC’s Limited Generation Profile approach, Stanfield noted. But these kinds of tools are starting to be developed in other states. That’s an important precursor to enable flexible interconnection, she said.

Can ​“flexible interconnection” expand community solar and batteries? 

To be fair, utilities have very good reasons to take a conservative, safety-first approach to interconnection. After all, they’re responsible for keeping grids safe and reliable — and distributed energy resources represent potential disruptions to those grids that utilities can’t directly control.

That’s why California’s Limited Generation Profile option won’t go into effect until nine months after certain power-system control technologies are certified by the Underwriters Laboratory standards organization as being able to reliably perform according to schedule. That’s expected to happen sometime within the coming year, Stanfield said.

Utilities have also been concerned that changes on their grids could leave circuits susceptible to dangerous conditions. CPUC’s new policy does allow utilities to curtail a project during emergencies or request a change to the project’s schedule in the highly unlikely circumstance of a ​“sustained load reduction” on a grid circuit — namely, if a major customer using that circuit closes down and permanently reduces electricity demand.

But under the new rules, utilities are largely required to honor the schedules they’ve agreed to with solar and battery projects, and to take on reasonable costs of grid upgrades to manage them. That’s a vital feature for any successful flexible-interconnection process, Stanfield said, because project developers secure investment for projects based on some level of certainty about how much power they’ll be able to sell over the project’s lifetimes.

Any utility program that injects too much uncertainty into that prospect — by, for example, retaining the right to unilaterally curtail a project’s grid exports without a clear and provable grid problem to justify it — won’t work for developers, she said.

“A flexible interconnection solution, if it’s modeled and can show what the impacts are going to be, might give developers a lot more certainty and more comfort,” said David Gahl, executive director of the Solar and Storage Industries Institute, during a November event held by the Interstate Renewable Energy Council. That nonprofit is leading a flexible-interconnection pilot project in New York state that’s funded by The U.S. Department of Energy’s Interconnection Innovation e-Xchange program.

Utopia Hill, CEO of Reactivate, a joint venture developing community-solar projects for disadvantaged communities, also noted at the November event that the key to future flexible-interconnection processes is increasing their predictability. ​“If we can’t get financing parties comfortable with that, we can’t get the funding to build the projects,” she said.

It’s still not clear if the CPUC’s Limited Generation Profile rules will meet that need for California solar and battery developers, said Kevin Luo, interconnection policy advisor for the California Solar & Storage Association trade group. One big question is whether the scheduling options approved by the CPUC will actually allow developers to design moneymaking projects.

“That’s one of the reasons why we pushed so hard for customers to be able to pick their own schedules,” he said — an option that the CPUC denied. ​“Nobody has done the forecasting work necessary to have the confidence in any one schedule.”

Nor are California’s solar policies and market dynamics aligned to support the 1-megawatt-and-up projects that the Limited Generation Profile option would be best suited to, Stanfield said. California lacks effective policies to promote the development of multi-megawatt, distribution-grid-connected community-solar projects or large-scale rooftop solar projects on warehouses or apartment complexes that would be eligible for the new interconnection treatment — although solar and environmental-justice groups are pushing regulators and lawmakers to change that.

Even so, Stanfield said, starting with a schedule-based approach at least begins to align utilities’ grid needs with the imperative to add far more solar and batteries to California’s grid. That way, ​“you can start to get some of the benefits now — and then we can build on that further.” 

California’s new rules allow solar and batteries to help out the grid is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.

It’s called the “solar coaster:” The ups and downs the industry faces as solar-friendly policies ebb and flow. And in North Carolina, rooftop installers are in the middle of one wild ride.

On the heels of cutting bill credits for residential solar panels in October, Duke Energy is now poised to offer new rebates for rooftop arrays that are paired with batteries. Combined with federal incentives, the new “PowerPair” rebates could cut the cost of solar and battery systems in half and inject new interest in rooftop solar, which many installers say waned last fall.

“We definitely saw a dip,” said Doug Ager, the CEO and co-founder of Sugar Hollow Solar, describing his company’s business in the last quarter of 2023. But at least in the short-term, he said, “PowerPair will change all that.”

Approved to roll out in May, the pilot program will initially serve only an estimated 6,000 to 7,000 households. But proponents say it could pave the way for a new paradigm in which Duke invests in and manages distributed renewable energy and storage the same way it might a traditional power plant.

“It’s opening the door to active load management from Duke that is going to be increasingly important,” said David Neal, the senior attorney with the Southern Environmental Law Center who helped negotiate the program. Heralding the pilot as one of the first of its kind, he said, “it’s going to be a lot more cost effective than just building new generation to meet expected loads.”

Ultimately, advocates are also hopeful that the solar coaster can be smoothed out a little.

“The rooftop solar industry really has experienced quite a bit of ups and downs,” said Matt Abele, executive director of the North Carolina Sustainable Energy Association, which also helped devise the rebates. There’s still the question of what long-term strategies would support installers, he said. “But I would say this is not an insignificant program in the interim.”

‘The result of…negotiations around net metering’

Greenlit by regulators last month, the rebates grew out of a years-long dispute between Duke Energy, advocates, and the solar industry about how rooftop solar owners should be compensated for the electricity they produce. 

About 40,000 rooftops across the state boast solar arrays, the bulk of them on homes and in Duke territory. The figure accounts for a tiny fraction of North Carolina’s roughly 5 million housing units.

Despite these small numbers, Duke, like other investor-owned utilities around the country, has long sought to lower the state’s one-to-one net metering credit, which it says unfairly burdens both the company and customers that don’t have solar panels.  

Solar installers and advocates contend that rooftop arrays provide more benefits than costs, including cleaner air, fewer electrons lost in transmission, and reduced need for electricity from centralized fossil fuel power plants. Their assertion is backed up by most independent studies of rooftop solar, a 2019 analysis found.

Still, a pair of state laws, both heavily influenced by Duke, mandate a change to the current net metering scheme by 2027. To avoid the bruising battles and excessive fees on solar customers seen in California and elsewhere, some of the state’s leading clean energy advocates and solar installers forged a complicated truce with the utility. 

The crux of the agreement is a move toward “time of use” billing. New residential solar owners are charged and rewarded more for electrons they add to or subtract from the grid during peak demand hours of 6 to 9 p.m. in the summer and 6 to 9 a.m. in the winter. On a monthly basis, any net solar electrons added to the grid are credited at the “avoided cost” rate — akin to a wholesale rate and currently about 3.4 cents per kilowatt hour.

Diligent solar owners can squeeze benefits out of this complex billing scheme, some installers say. But to ease the transition, they also negotiated a simpler, lower-risk “bridge rate” with Duke, in which solar customers enrolling before 2027 get a monthly credit at the wholesale rate for any electrons they add to the grid. 

Regulators on the utilities commission accepted these compromises last March and ultimately ordered new rates to begin October 1. But they rejected another component of the deal, which would have given customers with electric heat an extra rebate for enrolling in Duke’s smart thermostat program, in which the utility can make temperature adjustments from afar.  

“Instead, the Commission directs Duke to develop a pilot program,” their order read, “to evaluate operational impacts to the electric system, if any, of behind the meter residential solar plus energy storage.” 

PowerPair is the result. “This program was in many ways a result of our negotiations around net metering,” Dave Hollister, the president of Sundance Power Systems, said over email.

‘Possibly a win-win for everyone’ 

Devised after months of conversations between Duke, solar installers, clean energy advocates, and others, the new rebates would be based on the size of the solar array and battery and capped at $3,600 and $5,400 respectively. Combined with a 30% federal tax credit, the cash back could cut the cost of an average $40,500 system down to less than $20,000. 

For customers, the deal is “actually really, really good in terms of the economics,” one installer said. And for Duke, the rebates could prove a low-cost strategy for smoothing out spikes in demand and strengthening the resilience of the grid.

“Cost effective and dispatchable customer-sited resources are key components of our clean energy transition,” Lon Huber, a senior vice president at Duke, said in an email. “We are committed to expanding the scope and adding ways for our customers to deploy grid beneficial technology.”

Customers will be divided into two equal cohorts. Those subscribed to the simpler bridge will allow the utility to remotely control their battery up to 18 times a year and will earn an extra $37 a month on average. Enrollees in the more complicated time-of-use rate plan, on the other hand, won’t get monthly incentives but would have control of their batteries. 

“It will be interesting to see how many folks will allow Duke to control their battery and who wants to have that freedom and independence to manage their customer-generated electricity themselves,” Hollister said. “ We deal with so many folks who are looking for self-reliance and the idea of ‘smart grid’ is somewhat of a third rail for them.”

Already, batteries are popular options for rooftop solar customers. Installers say between a quarter and 40% of their clients were already choosing them for a variety of reasons, from a desire to save money to a quest for energy security in the face of outages. 

Sugar Hollow Solar’s Ager said residential storage fits with the western North Carolina vibe. “Being in the mountains,” he said, “people just want batteries.”

With the PowerPair, the percentage of solar arrays paired with storage will undoubtedly rise, and many installers predicted it would double. 

“I fully anticipate us selling tons of systems with batteries,” said Brandon Pendry, communications and outreach specialist with Southern Energy Management, one of the state’s oldest installers and a negotiator for both the bridge rate and the PowerPair scheme. 

To avoid the problem installers and their clients faced with the last round of rooftop solar rebates — when demand far exceeded supply each year and available grants disappeared in minutes — the architects of the program gave it an overall cap of 60,000 kilowatts but no annual limits. That way, rooftop solar and battery owners can get the rebates on a rolling basis.  

“In this case, there is only one capacity and it’s not time dependent,” said Pendry. “It’s just: when it runs out, it runs out.”

If customers choose the maximum allowable size of a 10 kilowatt solar array, a total of 6,000 households could benefit. But no one really knows when the capacity will be reached, with some predicting 18 months from May and others estimating as few as four. 

Duke projects it will connect 11,400 residential rooftop systems this year. But a spokesperson said it was simply too early to tell when PowerPair rebates would dry up. 

Once they do, the hope is that data gathered during the pilot will inform whatever comes next. 

“It may possibly be a win-win for everyone,” Hollister said, “especially if it can be extended or transformed into a more permanent program.” 

‘A better and better investment’

Since half of the PowerPair cohorts will be using the bridge rate, there’s some chance a permanent program would extend that rate’s life — a key priority for some in the industry.  

No matter what, while most installers contacted for this article eagerly await the pilot, they’re also clear-eyed about their business plan for the future.

“We have been installing solar in [the state] for over a decade and have certainly seen lots of incentives come and go, said Jesse Solomon, vice president and director of sales for N.C Solar Now, in an email. “But we have always been able to design the investment to make sense for our clients.” 

Solar installers also focus on the overall trends buoying their industry: Fossil fuels are becoming more expensive, while the materials designed to harness and store forever-free sunlight are getting cheaper.

Every year Duke raises rates, said Pendry of Southern Energy Management, “solar becomes a better and better investment.”

In North Carolina, Duke Energy to offer rebates for rooftop solar paired with batteries is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.