California’s rooftop solar market is undergoing its most significant structural shift in over a decade, and the fallout is reshaping how homeowners think about energy storage. Since April 15, 2023, every new solar interconnection applicant in the state has been placed on the Net Billing Tariff, a compensation framework that pays far less for electricity sent back to the grid than the old Net Energy Metering program did. The result: a growing number of solar customers are pairing panels with home batteries to capture value that the grid no longer rewards, and battery manufacturers are racing to keep up with demand.
What the Net Billing Tariff Actually Changed
The old Net Energy Metering system let solar homeowners sell surplus electricity to their utility at roughly the same retail rate they paid to buy it. That one-for-one exchange made rooftop solar a straightforward financial bet and was codified in successive NEM decisions detailed on the state regulator’s net metering page. The California Public Utilities Commission adopted Decision D.22-12-056, which created the Net Billing Tariff (often called NEM 3.0) and fundamentally altered that math. Under the new structure, export credits fluctuate based on the time of day and the grid’s real-time needs, meaning midday solar exports, when generation peaks and demand is relatively low, earn a fraction of what they once did.
The CPUC designed the change to better align rooftop solar incentives with actual grid costs. Utilities had argued for years that generous net metering shifted infrastructure expenses onto non-solar ratepayers. The commission’s analysis documents and fact sheets, available through its formal rulemaking docket, detail how the old program created a cost imbalance. But for homeowners who installed panels expecting decades of retail-rate credits, the policy change landed hard, especially as they realized that most of their midday production would now be compensated at rates closer to wholesale energy prices than to the retail charges on their bills.
Under Net Billing, the value of exported electricity is determined by hourly “avoided cost” values that try to capture what the utility would have paid for energy, capacity, and other services if that rooftop solar had not been available. In practice, that means solar customers see far lower credits in the middle of the day and somewhat higher ones in the early evening, when the grid is more stressed. The shift moves rooftop solar away from being a simple bill-offset tool and toward a resource that must be managed actively to capture value.
Why Batteries Became the Obvious Response
The economics are simple: if the grid pays less for exported solar power during the afternoon but charges high rates during evening peak hours, storing that energy and using it at night becomes the smarter play. A battery lets a homeowner absorb cheap midday generation and discharge it when electricity prices spike after sunset. That spread between low export credits and high evening rates is the financial engine driving the battery rush, and it aligns with the broader push by state policymakers in Sacramento to reduce evening peak demand without building new fossil fuel plants.
Lawrence Berkeley National Laboratory has been tracking this exact pattern. Its Tracking the Sun research program, which monitors distributed solar pricing and design trends nationwide, found that storage attachment rates in California have climbed sharply compared to the rest of the country. The state’s policy environment, where export credits dropped substantially while time-of-use rate differentials widened, created conditions that made batteries not just attractive but nearly essential for new solar installations to pencil out financially.
This is where the common narrative deserves some pushback. Many industry voices frame the battery boom as a pure win for consumers and the grid. But the reality is more complicated. Adding a battery system raises the upfront cost of a solar installation by thousands of dollars, and the payback period depends heavily on utility rate structures that regulators can change again. Homeowners are essentially betting that the current rate design will hold long enough for their investment to pay off, a bet that carries real risk given how quickly California’s energy policies have shifted in recent years.
There is also a technical dimension that rarely makes it into sales pitches. Batteries degrade over time, and their usable capacity can fall meaningfully over a decade of daily cycling. Under Net Billing, many homeowners will be cycling their batteries more aggressively to chase bill savings, which could shorten the effective life of the system if manufacturers’ performance guarantees are not robust. That trade-off between near-term savings and long-term durability is difficult for non-experts to evaluate.
Solar Installers Adjust to a New Market
The industry response has been swift but uneven. Sunrun, one of the largest residential solar companies in the United States, addressed the NBT’s impact directly in its SEC filings. The company’s Form 10-Q for the quarter ended March 31, 2025, included risk factor disclosures and market commentary about how the new tariff and related policy shifts could affect installation volumes. The filing suggests that while the tariff switch may slow pure solar-only sales in the near term, it is accelerating demand for integrated solar-plus-storage packages, which carry higher revenue per customer.
That dynamic creates winners and losers within the solar industry itself. Companies with established battery supply chains and installation expertise stand to gain market share, while smaller installers that built their business around simple panel-only jobs face margin pressure. The transition also shifts the sales conversation: instead of pitching solar as a way to zero out an electric bill through net metering credits, salespeople now have to explain battery cycling, time-of-use optimization, and backup power value, a more complex pitch that requires different training and customer trust.
Installers are also rethinking system design. Under Net Billing, oversizing a rooftop array purely to maximize exports makes less sense. Many designers are instead sizing solar closer to a home’s daytime load and allocating more of the budget to storage capacity. That change can reduce the visible footprint of rooftop systems while increasing the complexity hidden in the garage or side yard, where inverters, batteries, and control hardware now cluster.
Grid-Level Data Shows the Shift in Real Time
California’s distributed generation tracking portal, maintained by the state at californiadgstats.ca.gov, provides interconnection data that reflects how the market is evolving. While the portal tracks new connections and system sizes across utility territories, the broader trend lines confirm that distributed solar remains a growth market in California even under the new tariff, though the composition of new systems is changing. Fewer customers are installing panels alone; more are bundling storage from the start, especially in territories with steep evening price peaks.
Federal data tells a complementary story. The U.S. Energy Information Administration published a report on small-scale solar deployment that examined how state-level policy changes interact with national growth patterns. California’s shift away from traditional net metering is the most prominent test case for whether reduced export compensation dampens solar adoption or simply redirects it toward storage-paired systems. Early evidence points toward the latter, but the data window remains short enough that definitive conclusions would be premature.
From a grid-operations standpoint, the rise of behind-the-meter batteries could be a double-edged sword. On one hand, distributed storage can help smooth the notorious “duck curve” by shifting solar output into the evening. On the other, if thousands of batteries respond similarly to price signals without coordinated control, they could create new peaks or localized stress on distribution circuits. Regulators and utilities are only beginning to grapple with how to integrate these devices into broader resource planning.
The Affordability Question No One Wants to Answer
The biggest tension in this story is cost. Batteries make solar pencil out under the new tariff, but they also raise the bar for who can participate. A homeowner who might have afforded a modest solar-only system under the old rules may now be told that a financially viable package requires a battery that adds tens of percent to the project price. State incentive programs can offset some of that cost, particularly for lower-income customers and those in high fire-risk areas, but funding is finite and application processes can be daunting.
Equity advocates worry that Net Billing could widen existing gaps. Wealthier households with access to credit can install solar-plus-storage, shield themselves from rising rates, and even ride through blackouts with backup power. Renters and lower-income homeowners, meanwhile, remain fully exposed to utility bills that may rise as fixed grid costs are spread over a smaller base of volumetric sales. The CPUC’s own modeling acknowledges this risk, even as it argues that reforming net metering is necessary to prevent those same inequities from growing worse over time.
There is also the question of how long the current battery-driven economics will last. If future regulatory changes flatten time-of-use differentials or further reduce export credits, the payback for existing systems could lengthen. Conversely, if climate-driven heat waves push evening prices even higher, early adopters could see outsized benefits. In either case, homeowners are making long-lived investments in a policy environment that is anything but static.
For now, the Net Billing Tariff has accomplished one of its central aims: it has pushed the market to think beyond stand-alone rooftop solar and toward resources that can respond to the grid’s needs in time as well as in kilowatt-hours. Whether that evolution ultimately delivers a fairer, more resilient energy system, or simply a more complex one that rewards those with the means to navigate it, remains an open question as California’s experiment unfolds in real time.
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*This article was researched with the help of AI, with human editors creating the final content.
