Home Solar Battery Guide
How battery storage works, what it costs, and whether it is the right fit for your home.
Why Consider Battery Storage?
Solar panels generate electricity during the day, but your home uses power around the clock. Without a battery, excess daytime production goes back to the grid, and you buy electricity at retail rates in the evening. A battery changes that equation entirely.
Battery storage has become increasingly important since California adopted NEM 3.0 in April 2023. Under the new policy, the value of exported solar energy dropped significantly, making self-consumption the key to maximizing your return on investment. A battery lets you store your solar energy and use it when rates are highest -- typically between 4 PM and 9 PM.
Beyond financial savings, batteries provide backup power during grid outages. In California, where Public Safety Power Shutoffs (PSPS) have become a regular occurrence during fire season, that peace of mind is increasingly valuable.
How Solar Batteries Work
The concept is simple: charge during the day, use at night. Here is the daily cycle of a solar-plus-battery system.
Morning
Solar panels begin generating power at sunrise. Your home uses what it needs, and excess energy starts charging the battery.
Midday
Peak solar production. The battery reaches full charge. Any additional excess can flow to the grid for net billing credits.
Evening Peak
Solar production drops as the sun sets, but electricity rates peak (4-9 PM). The battery kicks in, powering your home with stored solar energy instead of expensive grid power.
Overnight
The battery continues to power your home until it depletes. Off-peak grid rates are lower, so any grid power you do use is at the cheapest time.
Battery Types and Chemistry
Lithium-Ion (Recommended)
The dominant technology for home solar batteries. Two main chemistries are used:
- LFP (Lithium Iron Phosphate): Longer lifespan (5,000+ cycles), more stable, no cobalt. Increasingly the standard for home storage.
- NMC (Nickel Manganese Cobalt): Higher energy density, slightly more compact. Well-established technology with strong track record.
Lead-Acid (Legacy)
An older technology still used in some off-grid applications. Generally not recommended for new home installations due to significant drawbacks:
- Shorter lifespan (500-1,500 cycles)
- Requires more maintenance
- Lower depth of discharge (50% vs 90%+)
Sizing Your Battery: How Many kWh Do You Need?
Battery sizing depends on your goals. There is a significant difference between covering your evening peak usage and providing whole-home backup during an extended outage.
The average California home uses 25 to 30 kWh per day. However, most of that usage happens during specific periods. Your evening and overnight usage, when solar panels are not producing, typically accounts for 10 to 15 kWh.
A single 10 to 13 kWh battery is usually enough to cover your peak evening hours (4-9 PM) and significantly reduce grid purchases. For whole-home backup that lasts through an extended outage, you would need 20 kWh or more, often requiring two battery units.
Battery Sizing Guide
Lights, refrigerator, Wi-Fi, phone charging, a few outlets. Keeps essentials running for 8-12 hours.
Covers evening peak hours. Best for maximizing NEM 3.0 savings. Most popular choice for grid-tied homes.
Powers everything including HVAC during outages. Usually requires two battery units. Ideal for areas with frequent PSPS events.
Multi-day autonomy for rural or off-grid homes. Three or more battery units paired with a large solar array.
Backup Power During Outages
Standard grid-tied solar systems shut down during power outages for safety -- this is a requirement to protect utility workers on the lines. A battery with an automatic transfer switch solves this problem. When the grid goes down, the system detects the outage, disconnects from the grid, and seamlessly switches to battery power within milliseconds.
During the outage, your solar panels continue charging the battery during daylight hours, creating a self-sustaining cycle that can keep your home powered for days. Most battery systems let you prioritize which circuits get backup power, so you can focus on the essentials like refrigeration, lighting, medical equipment, and internet connectivity.
For California homeowners in wildfire-prone areas where PSPS shutoffs can last 24 to 48 hours or longer, this capability is not just convenient -- it is essential. A properly sized solar-plus-battery system ensures your family stays comfortable and connected regardless of grid conditions.
Batteries and NEM 3.0: Maximizing Self-Consumption
5-8c
NEM 3.0 export value per kWh (average)
35-55c
Peak evening rate per kWh you avoid
6-7x
Value multiplier by storing vs. exporting
Under NEM 3.0, exporting excess solar to the grid earns you roughly 5 to 8 cents per kWh on average. But the electricity you buy during peak evening hours costs 35 to 55 cents per kWh depending on your utility and rate plan. That is a massive gap.
A battery bridges this gap. Instead of exporting your midday excess at low rates, you store it and use it during the expensive peak window. Every kWh you store and self-consume is worth 6 to 7 times more than exporting it. Over a year, this difference can amount to $1,000 or more in additional savings compared to a solar-only system.
This is why we recommend battery storage for virtually every new solar installation under NEM 3.0. The economics have shifted decisively in favor of self-consumption, and a battery is the tool that makes it possible.
Cost Ranges and ROI Timeline
A home battery storage system typically costs between $10,000 and $15,000 installed, depending on the capacity, brand, and installation complexity. This cost is eligible for the 30% federal Investment Tax Credit, bringing the net cost down to $7,000 to $10,500.
If you qualify for California's SGIP rebate, the cost can drop further. Customers in high-fire-threat districts or those who are medically vulnerable may receive enhanced rebates that cover a significant portion of the remaining balance.
The payback timeline for a battery depends on your rate plan, usage patterns, and whether you experience outages. In most cases, the financial return from peak-hour savings under NEM 3.0 gives batteries a payback period of 7 to 12 years. When you factor in backup power value and rising utility rates, the investment becomes increasingly attractive over the system's 10 to 15 year warranty period.
Battery Cost Example
Estimates based on average TOU rate differentials in PG&E and SCE territories. SGIP rebates, if available, would further reduce cost and payback period.
Is a Battery Right for You?
Use this framework to evaluate whether battery storage makes sense for your situation.
A Battery Is a Great Fit If...
You are on a TOU rate plan
Peak-hour rates of 35 to 55 cents per kWh make self-consumption extremely valuable.
You experience power outages
PSPS events, storm outages, or unreliable grid service make backup power worth the investment.
You are installing new solar under NEM 3.0
The economics of NEM 3.0 strongly favor solar-plus-battery systems over solar-only.
You have high evening energy usage
Families home in the evenings running AC, cooking, and using appliances benefit the most from stored solar.
Consider Carefully If...
Your budget is very tight
If the battery cost pushes your total investment beyond comfort, solar-only still saves significant money.
You are on a grandfathered NEM 1.0 or 2.0 plan
If you already have solar under NEM 2.0 with favorable export rates, the battery ROI may be longer.
You rarely experience outages
If backup power is not a priority and your grid is reliable, the pure financial case takes longer to pay off.
You plan to move soon
Batteries increase home value, but if you are selling within 2-3 years, you may not recoup the investment.
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