Is solar worth it for the average homeowner?

For most homeowners with monthly electricity bills over $100, solar delivers positive ROI in 2026. The national average payback period is 7–9 years, after which you produce free electricity for 15–18 more years. High-rate states like California, Hawaii, and Massachusetts see payback in 5–7 years.

When is solar NOT worth it?

Solar may not make sense if you plan to move in the next 3–5 years (though it adds home value), your roof needs major repairs, your electricity bill is under $60/month, you rent rather than own, your roof faces primarily north, or heavy shading from trees cannot be removed.

Does solar increase home value?

Yes. A 2019 Zillow study found homes with solar sold for 4.1% more than comparable non-solar homes. A Lawrence Berkeley National Lab study found buyers paid an average of $4/W premium for solar homes. For a 8 kW system, that's roughly $32,000 in added home value.

How does solar ROI compare to stock market returns?

Cash-purchase solar delivers an IRR of 8–15% over 25 years in most US markets — competitive with historical stock market returns and with the significant advantage of a predictable, inflation-hedged return. Unlike stocks, solar returns don't go negative when markets crash.

What electricity rate makes solar worth it?

As a rule of thumb, solar makes strong financial sense when your electricity rate exceeds $0.10/kWh. Below that threshold, payback periods stretch to 10+ years. Hawaii ($0.37/kWh), California ($0.22/kWh), and Connecticut ($0.25/kWh) offer the strongest financial case.

Does solar work on cloudy days?

Yes, modern panels produce electricity even on overcast days — typically at 10–25% of their rated output. Germany, one of the world's largest solar markets, has similar sun hours to Seattle. Production is reduced on cloudy days but not zero, and annual totals account for seasonal variation.

How Much Solar Do I Need to Power My House? 2026

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The Simple Formula to Calculate Your Solar System Size

Every solar installer uses a variation of the same core calculation. You can do it yourself in 60 seconds with your electricity bill:

System Size Formula

kW needed = Monthly kWh ÷ (Peak sun hours × 30 × 0.80)

Where: Monthly kWh = from your electricity bill | Peak sun hours = from NREL PVWatts for your zip code | 0.80 = real-world efficiency factor

System Size by Home Type and Usage

Home Type	Monthly Usage	System Size (Avg Sun)	Panels (400W)	Est. Cost After ITC
Small apartment / condo	400 kWh	3.2 kW	8 panels	$6,700
Small home (1,200 sq ft)	600 kWh	4.8 kW	12 panels	$10,100
Average home (1,800 sq ft)	900 kWh	7.2 kW	18 panels	$15,100
Large home (2,500 sq ft)	1,200 kWh	9.6 kW	24 panels	$20,200
Large home + 1 EV	1,500 kWh	12.0 kW	30 panels	$25,200
Large home + 2 EVs + pool	2,000 kWh	16.0 kW	40 panels	$33,600

System Size by Location — Same Home, Different Sun

Your location dramatically affects how many panels you need. A home using 900 kWh/month needs very different system sizes across the US:

City	Sun Hours	System Size for 900 kWh/mo	Number of 400W Panels
Phoenix, AZ	6.5	5.8 kW	15 panels
Los Angeles, CA	5.8	6.5 kW	17 panels
Dallas, TX	5.4	6.9 kW	18 panels
Denver, CO	5.3	7.1 kW	18 panels
New York, NY	4.7	7.9 kW	20 panels
Boston, MA	4.5	8.3 kW	21 panels
Seattle, WA	3.9	9.6 kW	24 panels

Should You Size Solar for 80%, 100%, or 110% of Usage?

Most installers recommend sizing for 100% of your annual electricity consumption. Here's the logic for each approach:

Offset Target	Pros	Cons	Best For
80% offset	Lower upfront cost, less excess production	Still pay electricity bills year-round	Budget-constrained buyers
100% offset	Eliminates electricity bills, optimal ROI	Some excess production in summer	Most homeowners
110–120% offset	Covers EV charging, future usage growth	Higher upfront cost, excess may earn low export rate	Homes planning EV or battery addition

What Your Electricity Bill Tells You

The most important number for solar sizing is your total annual kWh usage. Find it on your electricity bills — many utilities show 12-month usage on each bill. Divide by 12 for your monthly average. Key tip: use a full year of data, not just one month. Summer and winter usage often differ significantly, and annual average is the right input for solar sizing.

If you're adding an EV soon, add 300–400 kWh/month to your baseline. If you're planning a home addition, hot tub, or pool, add estimated usage for those loads. Solar sized today should reflect where your usage will be in 2–3 years, not just today's bills.

Roof Space: Do You Have Enough?

Each 400W panel takes approximately 18–19 sq ft of roof space. Here's how much roof area different system sizes require:

System Size	Panels (400W)	Roof Space Needed	Typical Roof Available
6 kW	15 panels	270–285 sq ft	✅ Most homes
8 kW	20 panels	360–380 sq ft	✅ Most homes
10 kW	25 panels	450–475 sq ft	⚠️ Larger homes
12 kW	30 panels	540–570 sq ft	⚠️ Needs good south-facing area

If your roof can't accommodate your ideal system size, high-efficiency panels (22%+ efficiency, like SunPower Maxeon or REC Alpha) produce more power per square foot — letting you fit a larger system in the same space, at a 30–40% price premium per watt.

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Frequently Asked Questions

How much solar do I need for a 2,000 sq ft house?

A 2,000 sq ft home typically uses 900–1,200 kWh/month. To fully offset this at national average sun hours (5.2 hrs/day), you need a 7.2–9.6 kW solar system — approximately 18–24 panels using 400W panels. Get 3 installer quotes based on your actual 12-month electricity usage, not square footage.

What is the formula to calculate solar system size?

System size (kW) = Monthly kWh usage ÷ (Peak sun hours × 30 days × 0.80 efficiency factor). Example: 900 kWh/month in Phoenix (6.5 sun hours): 900 ÷ (6.5 × 30 × 0.80) = 5.77 kW. In Boston (4.5 sun hours): 900 ÷ (4.5 × 30 × 0.80) = 8.33 kW.

How many solar panels does the average house need?

The average US home needs 18–24 solar panels (using 400W panels) to offset 100% of electricity usage. This equates to a 7.2–9.6 kW system. Smaller efficient homes may need only 12–15 panels; large homes or homes with EVs may need 25–35 panels.

Can solar panels power a house at night?

Not directly — solar panels only produce power during daylight. To power your home at night with solar, you need battery storage (Tesla Powerwall, Enphase IQ Battery) or net metering credits accumulated during the day. Most grid-tied solar homes use net metering to handle night-time consumption.

How much does it cost to fully power a house with solar?

Fully powering the average US home with solar costs $18,000–$28,000 installed before incentives, or $12,600–$19,600 after the 30% federal tax credit. High-usage homes or homes in less sunny climates need larger systems costing more. Get 3 competing quotes for accurate pricing.

Do I need to power 100% of my home with solar?

Not necessarily — many homeowners size solar to offset 80–90% of usage, leaving a small grid connection for cloudy periods. This reduces upfront cost while still dramatically cutting electricity bills. In states with good net metering, sizing for 100% annual offset makes financial sense.

How does adding an EV change my solar needs?

Adding an electric vehicle adds 250–400 kWh/month to your electricity consumption (based on 10,000–15,000 miles/year). This typically requires adding 2–4 more solar panels (0.8–1.6 kW) to your system. Plan for your EV when sizing solar — it's much cheaper to add panels upfront than to expand later.

How Much Solar Do I Need to Power My House?