Solar battery installation cost: the other half of the quote
Last reviewed · planning ranges, not quotes
Batteries are the one solar line item the 3.00/W panel arithmetic cannot describe: they price per usable kilowatt-hour, roughly $700-$1,200 installed for whole-home LFP systems. This page covers that half — sizing, pricing structure, and the honest question of when a battery earns its cost.
The pricing structure, plainly
A battery quote is three numbers stacked: hardware (per usable kWh), the balance of system (a compatible hybrid inverter or AC-coupled unit, switchgear, and a critical-loads panel), and labour and permitting. Whole-home LFP systems from major brands land around $700-$1,200 per usable kWh installed; adding a battery to an existing solar install usually prices higher per kWh than including it from day one, because the coupling hardware has nowhere to amortise. Rack-style batteries self-installed sit well below that band and carry the engineering and warranty risk in exchange.
Sizing: the two questions that set the bank
Self-consumption sizing (the common case): the bank needs to cover the evening and overnight draw you would otherwise buy from the utility — for most homes, roughly half of daily usage. A 30 kWh/day house is a 12-15 kWh bank; a lean 15 kWh/day house, 6-8 kWh.
Autonomy sizing (the off-grid case): the bank must carry whole days, and the off-grid guide's math — daily kWh × dark days ÷ 0.8 usable — produces the 2-4× bigger banks that real independence requires.
What shifts the price per kWh
- Chemistry and enclosure. LFP is the default today; premium enclosures and integrated thermal management price above bare rack modules.
- Coupling. DC-coupled (new builds, one inverter) usually beats AC-coupled retrofits on efficiency and cost.
- Critical-loads panel. Whole-home backup needs a subpanel rework; backing up selected circuits is cheaper and often smarter.
- Stacking small units. Per-kWh prices improve with bank size; the first unit carries fixed install costs.
When a battery earns its cost
Three situations, honestly ranked. Outages: if multi-hour or multi-day outages are a fact of your utility, resilience has value no payback formula captures — and a right-sized critical-loads battery replaces the generator conversation. Time-of-use or net-billing tariffs: if your utility buys solar cheap and sells evening power dear, shifting your own kilowatt-hours is a real arbitrage — size the bank to the evening peak, not the day's total. Everywhere else: a battery on a flat-rate tariff with decent net metering is a convenience purchase, and the honest move is enlarging the array instead. The calculator shows the panel-side arithmetic; the cost guide keeps the panels-only quote.
A worked quote, end to end
A home using 28 kWh a day on an evening-peak tariff wants about 13 kWh usable of battery: at $700-$1,200 per installed kWh that is a $9,000-$15,500 battery line, plus a hybrid inverter upgrade if the existing solar inverter is not battery-ready. Against a tariff spread of a few cents per shifted kWh, payback measured purely in arbitrage is long; measured against the outage it prevents and the generator it retires, the same number can be obviously worth it. That is the entire battery decision — priced per kilowatt-hour, judged per household.
Questions people ask
How much does a home solar battery cost installed?
Whole-home lithium-iron-phosphate systems from major brands run roughly $700-$1,200 per usable kilowatt-hour installed — a widely-quoted 13-14 kWh unit lands in the low-to-mid five figures with installation; smaller 5-10 kWh banks land in the mid four figures to five. Self-installed rack batteries cost materially less per kWh but assume you own the engineering, permitting, and warranty risk. Treat all of these as planning ranges, not quotes.
Why do batteries price per kWh while panels price per watt?
Panels are rated by power (watts) and their job is generating; batteries are rated by energy (kilowatt-hours) and their job is holding what was generated. The two numbers are not convertible — a 10 kW array and a 10 kWh bank are entirely different purchases. That is also why this page exists separately from the installation-cost guide, whose 3.00/W arithmetic deliberately covers panels only.
What size battery do I need?
Two questions set it. Evening self-consumption — running the house tonight on today's sun — typically wants roughly half your daily usage, so a 30 kWh/day home looks at a 12-15 kWh bank. Outright autonomy — surviving dark days — wants the days-of-autonomy math on the off-grid guide instead, which is how off-grid banks grow to 2-4× self-consumption size. Oversizing past your actual evening draw buys little; undersizing below it just means the grid covers the rest.
Did the federal tax credit cover batteries?
It did — qualifying home battery storage was covered by the same federal Residential Clean Energy Credit as panels, and it ended the same way: systems whose installation was completed after December 31, 2025 receive no federal credit. Some state and utility battery incentives survive and can be substantial in specific states; the state pages list what applies where.
Panel-side constants (3.00/W, PR 0.8) from the methodology page; battery figures are planning ranges as of , reviewed by SolarDime editorial. Verify current incentive and tariff details with your utility and installer.
Data sources and assumptions
- Electricity ratesU.S. EIA · 2026 state averages
- Solar resourceNREL · 2026 state averages
- Federal tax treatmentIRS · Credit ended for installations completed after 31 Dec 2025 (P.L. 119-21)
- Installed costInstalled cost per watt · 2026 estimate, user-editable
State assumptions last reviewed: . Rules can change; verify your utility and state program before signing a contract. Full methodology.