Assumes 3%/yr rate increases, 0.5%/yr panel degradation and no federal tax credit (the 30% §25D credit ended for systems installed after Dec 31, 2025). How we calculate
Data approachEIA rates · NREL sun hours · 2026 federal policy · methodology
A home using 80 kWh per day needs roughly 15–29 kW of solar, or about 39–72 panels at 400W, depending on how much sun the location gets. At the 4.5 peak-sun-hour national benchmark, the answer is about 22 kW (56 panels). In 2026 that costs roughly $55,500–$77,700 before incentives, and the 30% federal credit for homeowner-owned systems ended on December 31, 2025.
For context, the U.S. Energy Information Administration (EIA) reports the average residential customer bought 10,791 kWh in 2022, about 29.6 kWh per day. At 80 kWh per day (29,200 kWh a year) you use about 2.7 times that. Common causes are multiple HVAC systems, electric heat, a pool pump, EV charging, a hot tub or a workshop. Before sizing, pull 12 months of bills: if 80 kWh is your summer peak rather than your yearly average, your system can be smaller. Efficiency upgrades are usually cheaper per kWh than panels.
Last updated October 2, 2026. Figures are estimates for planning, not a quote, and this page is not tax or financial advice.
⚡ System Size
How Many Solar Panels Do You Need for 80 kWh Per Day?
Divide your daily kWh by your location’s peak sun hours, then divide by system efficiency to cover inverter, wiring and temperature losses.
Formula: System size (kW) = Daily kWh ÷ Peak sun hours ÷ System efficiency
At 4.5 peak sun hours and 80% efficiency: 80 ÷ 4.5 ÷ 0.80 = 22.2 kW. We use 80% to stay conservative; NREL’s PVWatts calculator defaults to roughly 14% system losses, so real results can come in slightly better. The table applies the same formula across typical sun-hour conditions.
Peak sun hours
System size
400W panels
440W panels
500W panels
3.5
28.6 kW
72
65
58
4.0
25.0 kW
63
57
50
4.5 (benchmark)
22.2 kW
56
51
45
5.0
20.0 kW
50
46
40
5.5
18.2 kW
46
42
37
6.0
16.7 kW
42
38
34
6.5
15.4 kW
39
35
31
Data visualization
System size needed for 80 kWh per day, by peak sun hours. At 4.5 sun hours the array is 22.2 kW, versus 28.6 kW at 3.5. Source: NREL PVWatts method; Green Energy Calculators calculation (80 ÷ sun hours ÷ 0.80).
Chart summary: Sun hours drive system size more than any other factor. Moving from 3.5 to 6.5 peak sun hours cuts the required array from 28.6 kW to 15.4 kW, a difference of about 13 kW or roughly 33 panels at 400W. A home in a cloudy region needs nearly twice the array of a desert home to cover the same 80 kWh.
Roof space matters too. A modern 400W panel covers roughly 18–22 square feet, so 56 panels need on the order of 1,000–1,250 square feet of unshaded, well-oriented roof. If space is limited, higher-wattage panels reduce the count, but utilities and local rules may also cap system size, so check yours. To size a system from your ZIP code and roof orientation, use NREL’s free PVWatts calculator or our solar system size calculator.
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💰 System Cost
How Much Does a Solar System for 80 kWh Per Day Cost in 2026?
Residential solar has recently priced at roughly $2.50–$3.50 per watt before incentives, according to EnergySage marketplace data reported in early 2026. Applying that range to the system sizes above:
Location type
System size
$2.50/W
$3.00/W
$3.50/W
Sunny (6.5 sun hours)
15.4 kW
$38,500
$46,200
$53,900
Benchmark (4.5 sun hours)
22.2 kW
$55,500
$66,600
$77,700
Cloudy (3.5 sun hours)
28.6 kW
$71,500
$85,800
$100,100
Data visualization
Estimated cost of a solar system for 80 kWh per day, before incentives. A 22.2 kW system runs about $55,500–$77,700 at $2.50–$3.50 per watt. Source: EnergySage marketplace data 2026; Green Energy Calculators calculation.
Chart summary: Location changes the bill as much as the price per watt does. A sunny-site array of 15.4 kW costs $38,500–$53,900, while a cloudy-site array of 28.6 kW costs $71,500–$100,100. These figures are before any incentives, because the federal homeowner credit does not apply to 2026 purchases.
Federal incentives changed in 2026. The 30% Residential Clean Energy Credit (Section 25D) applied only to homeowner-owned systems completed by December 31, 2025. For cash or loan purchases completed in 2026, the federal credit is $0. Solar owned by a third party (lease, power purchase agreement or prepaid contract) can still qualify for the business credit (Section 48E), subject to the project’s construction-start and placed-in-service rules, but the savings reach you only through the contract terms, and the provider keeps ownership of the system. Ask any provider for the full 25-year payment schedule, including escalators.
State and local incentives still exist in some places, including state tax credits, utility rebates and property-tax exemptions, but they vary widely and change often. Check the DSIRE database and your utility before assuming any number.
Why do quotes differ so much? Equipment brand, labor rates, permitting, roof complexity, inverter type and installer overhead all vary by region. Request at least three quotes with identical system size and equipment, and ask for the price per watt. Our solar tax credit calculator can help you see which incentives still apply.
Solar vs utility company · 25-year comparison
25-year totals: 3%/yr rate increases, 0.5%/yr degradation, no federal credit. Methodology
Worked Example: What 80 kWh Per Day Costs on the Grid vs. Solar
This is a transparent model, not a case study of a real home. The goal is to show how the numbers connect so you can replace our assumptions with yours.
Assumptions: 80 kWh per day (29,200 kWh per year); 4.5 peak sun hours; 22.2 kW system; 100% of production valued at your retail rate through full net metering; 17.3¢/kWh, the EIA’s preliminary 2025 U.S. average residential price; electricity prices rising 2% a year; panel output declining 0.5% a year.
Year 1 on the grid: 29,200 kWh × $0.173 = about $5,050 per year, or $421 per month.
Your rate changes the picture quickly. State averages in EIA’s Electric Power Monthly range widely: for example, November 2025 residential averages were about 27¢/kWh in Connecticut, 26¢ in New York and 31¢ in Massachusetts. The arithmetic is simple: kWh per year × your rate.
At 80 kWh a day (29,200 kWh a year), each 1¢ per kWh adds about $292 to the annual bill: about $2,920 at 10¢, $5,050 at the 17.3¢ U.S. average, $7,300 at 25¢ and $8,760 at 30¢. The higher your rate, the more each solar kWh is worth, which is why identical systems pay back at very different speeds across states.
📋 Key Insights
How Long Does It Take an 80 kWh/Day Solar System to Pay for Itself?
Using the assumptions above and no federal credit, a 22.2 kW system reaches break-even in about 10 years at $2.50/W, 12 years at $3.00/W and 14 years at $3.50/W. Over 25 years, the $3.00/W case produces about $85,100 in modeled net savings.
Data visualization
Modeled cumulative cash flow of a 22.2 kW system reaches +$85,075 by year 25 at $3.00 per watt. Assumes 17.3¢/kWh rising 2% a year, 0.5% annual degradation, full retail net metering and no federal credit. Source: EIA 2025 price; Green Energy Calculators model.
Chart summary: All three price scenarios cross zero between years 10 and 15 and finish positive by year 25, ranging from about $74,000 to $96,000 in modeled net savings. The lines run roughly parallel: each extra $0.50/W of installed cost adds about two years to payback and subtracts about $11,000 from the 25-year result.
How sensitive is the result to the assumptions? At $3.00/W:
Electricity at 27¢/kWh: payback in about 8 years.
Electricity at 10¢/kWh: payback in about 20 years.
No annual rate increases: payback in about 13.6 years.
The model leaves out inverter replacement (string inverters often need one within the system’s life), maintenance, insurance, loan interest and any change in export credits, so treat it as a best-case view of a system valued at full retail rates. If your utility pays less than the retail rate for exported power, or charges fixed fees, payback gets longer. Use our solar payback calculator and solar savings calculator with your own rate. Resale premiums for solar homes vary by market and are not guaranteed, so we do not count them here.
🔋 Storage
Does an 80 kWh/Day Home Need Battery Storage?
If your utility offers full retail-rate net metering, the grid works as a free battery: you export in the day and import at night at the same price. In that case a battery mainly buys backup power. Storage can change the math if you have frequent outages, time-of-use rates with expensive evenings, or a utility that pays low credits for exported solar. California, for example, moved new solar customers to a net-billing structure in 2023 that favors self-consumption.
Because the federal homeowner credit ended in 2025, batteries bought in 2026 generally do not qualify for it either. Battery capacities for common products:
Battery
Usable capacity
Tesla Powerwall 3
13.5 kWh
SolarEdge Home Battery
9.7 kWh
Enphase IQ Battery 5P
5 kWh per unit (stackable)
Backing up a full 80 kWh day would take about six Powerwall 3 units (6 × 13.5 = 81 kWh), which is rarely practical. Most owners protect critical loads instead, such as refrigeration, internet, lighting, well pump and one or two HVAC zones, and the battery count depends on those loads. Battery prices change quickly, so get written quotes. Our battery storage calculator can help you compare scenarios.
Installed cost range ($2.50–$3.50 per watt): EnergySage marketplace data, as reported in early 2026. Prices vary by region and installer.
Federal tax credit status: Section 25D ended December 31, 2025 under the One Big Beautiful Bill Act, signed July 4, 2025; Section 48E remains for provider-owned systems that meet its rules. Confirm current rules with a tax professional.
Solar production estimates: use NREL’s PVWatts calculator for your address. State and utility incentives: DSIRE.
Calculations: system size = daily kWh ÷ peak sun hours ÷ 0.80; payback and cash-flow figures come from the model assumptions stated above and are illustrative, not a guarantee of savings.
Related calculators
Free tools for US homeowners — instant results, all 50 states.
Direct answers for US homeowners — sized for a $421/month electric bill.
At the common 4.5 peak-sun-hour benchmark and an 80% system efficiency, you need about 22.2 kW of solar, which is roughly 56 panels rated at 400W. The range is wide: about 15.4 kW (39 panels) in a sunny location with 6.5 sun hours, up to about 28.6 kW (72 panels) with only 3.5 sun hours. The formula is daily kWh ÷ peak sun hours ÷ efficiency. Check your own location in NREL's free PVWatts calculator.
Residential solar has recently priced at roughly $2.50–$3.50 per watt before incentives, according to EnergySage marketplace data. For a 22.2 kW system that is about $55,500–$77,700, with $66,600 at the $3.00/W midpoint. Sunnier locations need smaller arrays and cost less; cloudier ones need about 28.6 kW and can exceed $85,000. Quotes on identical equipment can differ by thousands of dollars, so compare at least three.
Not for a system you buy with cash or a loan. The homeowner credit (Section 25D) ended for installations completed after December 31, 2025, under the One Big Beautiful Bill Act. Provider-owned systems (leases, PPAs and prepaid arrangements) can still benefit from the business credit (Section 48E) if the provider's project qualifies, but any savings reach you only through the contract's pricing. Confirm eligibility with your installer and a tax professional, and check DSIRE for state and utility incentives.
In our model, a 22.2 kW system with 100% retail-rate net metering, a 17.3¢/kWh rate rising 2% a year and 0.5% annual panel degradation pays back in about 10 years at $2.50/W, 12 years at $3.00/W and 14 years at $3.50/W. Your electricity rate matters most: the same $3.00/W system pays back in about 8 years at 27¢/kWh and about 20 years at 10¢/kWh. Reduced export credits, fees or loan interest lengthen payback.
Not necessarily. Where your utility offers full retail-rate net metering, the grid acts as your storage and batteries mainly add backup power. Batteries make more sense for frequent outages, time-of-use rates, or utilities that pay low export credits. Backing up a full 80 kWh day would take about six Tesla Powerwall 3 units (13.5 kWh usable each), so most homeowners back up critical loads such as refrigeration, internet and a few circuits instead.
Same usage, bill-based guide
Your 80 kWh/Day target maps to roughly a $400/month electric bill nationally.
18.19¢/kWh — US average residential price. Source: EIA Electric Power Monthly, Table 5.6.B (year-to-date through July 2026), residential average retail price (July 2026) (EIA)
Solar production
4.5 peak sun hours/day × 0.82 system derate. Approximate state-average daily solar resource (peak sun hours) based on NREL solar resource data (NSRDB); not location-specific — use NREL PVWatts for an address-level estimate. (NREL PVWatts)
Installed price
$3.00 per watt before incentives. Blended 2026 US residential installed price used by this site; EnergySage marketplace reported about $2.60/W (mid-2026); full-market medians are higher.
Federal tax credit
$0 for homeowner-owned systems installed in 2026 — the 30% §25D credit ended Dec 31, 2025 (IRS)
Net metering
National blend — solar assumed to offset 75% of the bill (87% in full-retail net-metering states, 55–70% elsewhere).
Estimates only — not tax, legal or financial advice. Get at least three installer quotes and confirm incentives with your utility and a tax professional.