California changed the economics of rooftop solar when NEM 3.0, officially called the Net Billing Tariff, took effect for new interconnections on April 15, 2023. Today, homeowners need to think about more than how much electricity their solar panels produce. They also need to consider when they use electricity, how much exported solar is worth, and whether storing that energy makes more sense.
That is where reliable backup power, a solar power generator, a whole home power generator, and portable backup power can fit into a broader home energy strategy.
This article explains why solar-only systems became less attractive under NEM 3.0, why batteries became more popular, when a battery retrofit makes sense, and what to compare before buying a storage system.
What changed when California replaced NEM 2.0 with NEM 3.0?
The biggest change is simple: excess solar electricity is generally worth less when you send it to the grid than when you use it yourself.
Under NEM 2.0, excess solar generation could earn credits close to retail electricity rates. Under NEM 3.0, or the Net Billing Tariff, exported electricity is compensated using rates based on the value of that energy to the grid. Those rates are usually below retail prices, although certain high-demand periods can offer higher compensation. (California Public Utilities Commission)
This creates a timing problem for solar homeowners.
Solar panels generally produce the most electricity around midday. Household electricity use often rises later in the afternoon and evening.
Without a battery, a homeowner may export surplus solar during the day and then buy electricity back from the grid later.
With a battery, that daytime solar can be stored and used after the sun goes down.
The key NEM 3.0 lesson is that using more of your solar power at home can be more valuable than simply producing more of it.
Why did solar-only ROI decline under NEM 3.0?
Solar-only systems can still save money, but the return depends more heavily on how much electricity the home uses while the panels are producing.
Consider two homes with identical solar systems.
Home A has someone working remotely during the day. The air conditioner, computers, appliances, and other equipment regularly run while solar production is high.
Home B is mostly empty during the day. Its electricity demand increases after work, when solar production is falling.
Home A can use much of its electricity directly. Home B is more likely to export solar power and then purchase electricity later.
That difference matters much more under NEM 3.0.
The CPUC notes that onsite solar first serves the home's electricity demand, while exported energy receives separate compensation under the Net Billing Tariff. Storage can help shift excess solar into periods when electricity has greater value. (California Public Utilities Commission)
So the question has changed from:
How much solar can my roof produce?
to:
How much of my solar energy can I use or store before exporting it?
Why did batteries become more attractive after NEM 3.0?
Battery storage helps solve the mismatch between when solar power is produced and when the home needs it.
A typical battery strategy is straightforward:
Daytime: Solar powers the house and charges the battery with excess generation.
Evening: The battery supplies stored solar energy instead of relying as heavily on the grid.
Outage: The battery can provide backup power to selected circuits or, with an appropriate system, much more of the home.
This can improve the value of solar by reducing low-value exports and replacing higher-cost grid electricity later.
California's storage market reflects that shift. The CPUC reported that batteries were paired with about 69% of NBT solar installations in 2024, compared with 22% for NEM installations. The data includes new solar-plus-storage systems as well as some batteries added to existing solar systems. (California Public Utilities Commission)
EIA data also showed that more than half of new California residential solar installations were paired with batteries by April 2024, up from just over 20% in October 2023. (U.S. Energy Information Administration)
The shift is clear: storage is no longer just an optional add-on for some solar buyers. For many NEM 3.0 customers, it is central to the economics.
Did battery retrofits actually surge?
Battery adoption surged, but most new storage was still paired with new solar rather than being a retrofit.
That distinction matters when you already own solar.
A retrofit means keeping the existing solar array and adding a battery later. This can be appealing when the panels still perform well and the homeowner wants to capture more value from daytime production.
A retrofit may make sense when:
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Existing solar production remains strong.
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The home exports a lot of electricity during the day.
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Evening electricity use is high.
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The homeowner wants outage protection.
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Existing equipment can support the new battery configuration.
For an older solar system, adding storage can be a more practical option than rebuilding a working system from scratch.
Can you add a battery to an existing solar system?
Yes, in many cases, but compatibility is critical.
One common approach is AC coupling. In simple terms, the battery operates alongside an existing grid-tied solar inverter instead of requiring the entire solar system to be replaced.
That can make retrofits easier, but the details depend on the existing equipment and electrical setup.
Before buying, check:
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Whether the battery supports your existing solar inverter.
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How the system behaves during a grid outage.
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Which circuits will receive backup power.
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What electrical work or transfer equipment is required.
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Whether the system can be expanded later.
Nature's Generator's MyGrid 10K Whole Home Generator is designed for home energy storage and AC-coupling applications. It provides 10,000W of continuous output, 10,496Wh of LiFePO4 battery storage, 120/240V split-phase operation, and expandable battery capacity.
Compatibility still needs to be confirmed for the specific solar installation. A system being capable of AC coupling does not mean it will work with every inverter or electrical configuration.
How much battery storage do you really need?
Start with your electricity usage, not the battery's headline capacity.
A larger battery is not automatically a better investment.
Suppose your home typically uses 8 to 12 kWh between late afternoon and bedtime. A battery sized around that pattern may provide more practical value than one that is much larger but rarely gets fully used.
Power output matters too.
kWh vs. kW
kWh measures stored energy.
kW measures how much power the system can deliver at once.
A battery can have plenty of stored energy but still struggle with large loads if its inverter output is too low.
That matters when you want to run equipment such as:
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Air conditioners
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Pumps
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Electric water heaters
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Electric cooking appliances
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Multiple large appliances at once
For whole-home backup, look at both battery capacity and continuous output.
How do you calculate battery retrofit payback?
A simple starting formula is:
Battery payback = net battery cost ÷ additional annual savings
You can estimate the annual savings by looking at how much solar energy the battery shifts into periods when grid electricity would have been more expensive.
For example, assume a battery shifts 10 kWh per day on 300 days per year, and the average avoided-cost difference is 30 cents per kWh.
10 kWh × 300 days × $0.30 = $900 per year
A $7,000 retrofit would have an illustrative simple payback of about 7.8 years.
This is only a starting estimate. Actual results depend on battery efficiency, degradation, installation costs, electricity rates, financing, and how often the battery can be charged and discharged effectively.
Before buying, use your actual utility bills and, ideally, hourly consumption data.
Three numbers are especially useful:
Annual electricity use: How much power does the household consume?
Daytime usage: How much is consumed while solar production is high?
Evening usage: How much is consumed after solar production drops?
These numbers can tell you whether a battery is likely to add meaningful financial value.
What should you compare before buying a post-NEM 3.0 battery?
Look beyond price and battery size.
For example, the MyGrid 10K provides 10,000W of continuous output, 10,496Wh of LiFePO4 storage, 120/240V operation, and substantial expansion potential.
For a different setup, the Powerhouse Gen 2 Whole Home Solar Generator offers up to 7,200W of 120/240V output, 4,800Wh of battery storage, solar charging, and modular expansion.
The right system depends on whether you care most about bill savings, outage protection, system expansion, or a combination of all three.
Is solar-only still worth buying under NEM 3.0?
Yes, especially for homes that use a lot of electricity during the day.
Solar-only can still work well for households with:
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Home-office loads
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Daytime air conditioning
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Pool equipment
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Regular daytime appliance use
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EV charging during solar hours
Homes with low daytime consumption may benefit more from storage because more of their solar production would otherwise be exported.
That is why there is no universal answer to solar versus battery.
The better question is:
How much solar should I install, how much should I store, and when will I use the electricity?
The CPUC similarly points to storage as a way to save excess solar for later use instead of immediately exporting it. (California Public Utilities Commission)
Homeowners should also use current incentive information when calculating ROI. According to the IRS, the federal Residential Clean Energy Credit is not available for qualifying property placed in service after December 31, 2025. (IRS)
That makes current, project-specific math more important than older solar calculators.
Should you choose a battery retrofit or a whole-home solar generator?
Choose a battery retrofit when the main goal is improving the economics of an existing solar system. Choose a whole-home solar generator when broader backup flexibility is equally important.
A retrofit can be attractive when you already have productive solar panels and want to move more of that energy into evening hours.
A whole-home solar generator may make more sense when you also want high-power backup, flexible charging, and expandable storage.
Nature's Generator's MyGrid 10K combines 10,000W output, 10,496Wh of LiFePO4 storage, 120/240V operation, and expansion capability.
The Powerhouse Gen 2 starts with 4,800Wh of storage, provides 7,200W of output, and can be expanded with additional units and Power Pods.
The best choice is not necessarily the largest or most expensive system. It is the one that matches your actual electricity use and backup needs.
Conclusion
NEM 3.0 did not make rooftop solar a bad investment. It changed how homeowners get the most value from it.
The biggest change is timing. Under California's Net Billing Tariff, exported solar power is generally worth less than retail electricity, while using solar directly or storing it for later can deliver more value. (California Public Utilities Commission)
That helps explain why battery storage became so common. In 2024, batteries were paired with about 69% of NBT solar installations, compared with 22% of NEM installations. (California Public Utilities Commission)
For homeowners who already have solar, adding storage can be a smarter move than replacing a working array. For new installations, storage deserves consideration from the beginning.
