US residential solar · 2026 data

How Many Solar Panels Does a Log Cabin Need in 2026?

Q: How much does it cost to power a log cabin with solar?

A grid-tied system costs roughly system watts times your local price per watt; at an assumed $3.00/W, a 5.6 kW system is about $16,800. Off-grid systems cost more because they add batteries, a charge controller and a larger inverter, and the battery bank is often the largest single line item. Costs vary widely by site access, battery size and labor rates, so get at least two written local quotes. Permits and inspections are usually required even for DIY installs.

Q: Is there a federal tax credit for cabin solar in 2026?

No. The residential clean energy credit (§25D), which covered 30% of solar panels and batteries of 3 kWh or more on a home you used as a residence, including a second home, ended for expenditures after December 31, 2025, under Public Law 119-21. An expenditure counts as made when installation is completed, so a system finished in 2025 is claimed on the 2025 return. Check DSIRE for state and utility incentives, and ask a tax professional about your situation. This is not tax advice.

Q: What size battery bank does an off-grid log cabin need?

Multiply daily kWh by days of autonomy, then divide by usable depth of discharge. For a 10 kWh/day cabin and 2 days of autonomy, lithium iron phosphate (LFP, about 85% usable) needs roughly 24 kWh of rated capacity, while lead-acid (about 50% usable) needs 40 kWh. LFP also lasts about 3,000–6,000 cycles versus roughly 400–1,200 for lead-acid, which is why it is usually cheaper over 20 years. In cloudy regions, plan 3–4 days of autonomy or add a backup generator.

Q: Is off-grid solar cheaper than extending power lines to a cabin?

It depends on distance. Line extensions can cost tens of thousands of dollars far from existing lines, which often favors off-grid solar. Close to the grid, connecting and adding rooftop solar is often cheaper than a large battery system. Get a written extension quote from your utility or electric co-op and compare it with a complete off-grid quote that includes a battery replacement. Off-grid also keeps power on during grid outages but makes you responsible for batteries and winter production.

Est. net savings

$12,160

Est. over 25 years (grid-tied, flat rates) · no federal credit

$16,800 Installed cost (assumed)

13.7 yrs Simple payback

5.6 kW System size

Typical result:

Full-time cabin: ~20 kWh/day (~$100/mo on grid at 16.3¢)
Grid-tied: 14 panels (5.6 kW) at 4.5 sun hours
~$16,800 installed at an assumed $3.00/W; off-grid adds batteries
~13.7-year simple payback under these assumptions

✓ EIA rates & NREL sun data ✓ 2026 federal policy applied ✓ Open methodology

Updated October 1, 2026 · 10 min read ·By Green Energy Calculators Editorial Team

Calculate My System Size View State Data

25 years without solar vs with solar

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

Without solar

25-year utility bills

$29,750

Rates rise ~3% per year

With solar

System cost + remaining bills

$17,590

Installed cost, no federal credit

Difference

Estimated 25-year net

+$12,160

Before any state or utility incentives

Author Green Energy Calculators Editorial Team

Editorial policy No paid placements

Last updated Oct 1, 2026

Data approach EIA rates · NREL sun hours · 2026 federal policy · methodology

Disclosure: links marked † are affiliate links — we may earn a commission at no extra cost to you. It never changes our calculations. Details

Disclosure: This article contains an affiliate link to Shop Solar Kits. If you purchase through it, we may earn a commission at no extra cost to you. This does not affect our recommendations.

Last updated October 1, 2026. Figures are estimates built from the stated assumptions; replace them with your own utility rate, sun hours and local quotes.

A log cabin needs 2–4 solar panels (400 W) for a weekend retreat using 3–5 kWh a day, and 13–19 panels for a full-time cabin using 20–30 kWh a day, plus a battery bank if it is off-grid. Off-grid systems cost substantially more than grid-tied ones because of batteries, and the battery bank is often the largest line item. The 30% federal credit ended for systems completed after December 31, 2025, so budget at full price.

Three numbers decide your panel count: how much power the cabin uses each day, how many peak sun hours your site gets (roughly 3.5–4 in cloudy northern areas to 6 or more in the desert Southwest), and whether you are off-grid (size for the darkest month and add batteries) or grid-tied.

For a grid-tied cabin, the math matches a regular home. A full-time cabin using about 20 kWh a day (7,300 kWh a year, roughly $100 a month at an assumed 16.3¢/kWh) needs about 5.6 kW (14 panels at 4.5 sun hours). At an assumed $3.00/W that is about $16,800 and a simple payback of about 13.7 years before any rate increases. See our methodology.

How Do You Calculate How Many Solar Panels a Log Cabin Needs?

Divide your daily kWh by your peak sun hours, divide by 0.82 for system losses, then divide by 0.4 kW per panel. The 0.82 factor is a conservative allowance for inverter, wiring, temperature, soiling and (off-grid) charge and battery losses. It is slightly below the roughly 0.86 default derate in the PVWatts calculator.

Panel count = (Daily kWh ÷ Peak sun hours) ÷ 0.82 ÷ 0.4

Example, a cabin using 10 kWh a day at 5 peak sun hours:

(10 ÷ 5) ÷ 0.82 ÷ 0.4 = 6.1, rounded up to 7 panels (2.8 kW)

The same cabin at 3.5 peak sun hours: (10 ÷ 3.5) ÷ 0.82 ÷ 0.4 = 8.7, rounded up to 9 panels.

Look up your site’s sun hours, including month-by-month values, in the PVWatts Calculator or the EIA’s solar resource overview. For an off-grid cabin without a generator, size for your worst month rather than the annual average; undersizing for December means running short exactly when it is hardest to fix.

Panels needed for a 10 kWh/day cabin by peak sun hours (x-axis). From 9 panels at 3.5 sun hours to 5 at 6.5. Calculated with the formula above (400 W panels, 0.82 efficiency, rounded up); sun-hour values are scenarios, check yours in NREL PVWatts.

Chart summary: For the same 10 kWh/day load, panel count falls from 9 at 3.5 sun hours to 5 at 6.5, so location alone swings the hardware by almost half. If your worst winter month has far fewer sun hours than the annual average, use that month’s value in the formula for an off-grid cabin.

Use our off-grid solar system size calculator to run these numbers for your cabin load and location.

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How Many Panels by Cabin Type and Size? (2026 Reference Table)

From 2–4 panels for a small weekend retreat to 22–28 panels for a large cabin with EV charging. The table uses 400 W panels, 0.82 efficiency and 5.0 peak sun hours (each panel ≈ 1.64 kWh/day). Adjust for your site with the formula above.

Log cabin solar sizing by cabin type (400 W panels, 5.0 sun hours, 0.82 efficiency; battery = LFP sized for 1 day of use at 85% usable depth of discharge)

Cabin type	Daily kWh	Panels (400 W)	System size	LFP battery, 1 day (rated)
Off-grid weekend retreat (400 sq ft)	3–5	2–4	0.8–1.6 kW	4–6 kWh
Small seasonal cabin (600–800 sq ft)	6–10	4–7	1.6–2.8 kW	7–12 kWh
Mid-size year-round cabin (1,000 sq ft)	12–18	8–11	3.2–4.4 kW	14–21 kWh
Full-time cabin (1,200–1,500 sq ft)	20–30	13–19	5.2–7.6 kW	24–35 kWh
Large cabin with EV charging	35–45	22–28	8.8–11.2 kW	41–53 kWh

Double the battery column for two days of autonomy. The square-footage ranges are typical examples, not measured data; your own appliance list matters more than cabin size.

Typical load surprises are electric water heaters (several kWh a day), electric space heaters (often 3–6 kWh a day if used heavily) and EV charging (roughly 10–12 kWh per 40 miles). Using propane for heating, hot water and cooking can cut the solar requirement substantially. Owners in cold climates such as Colorado, Montana or Minnesota commonly underestimate winter heating loads and overestimate winter sun, a frequent reason off-grid systems underperform in year one.

If you prefer a pre-built option, off-grid solar kits from Shop Solar Kits (affiliate link) are one place to compare. Check the retailer’s page for current pricing and promotions, and make sure any kit matches your calculated panel count, inverter size and battery capacity.

How Much Does a Log Cabin Solar System Cost in 2026?

A grid-tied cabin system costs roughly system watts × price per watt; at an assumed $3.00/W, a 5.6 kW system is about $16,800. Off-grid systems (panels, inverter, charge controller, batteries, mounting and wiring) cost more because batteries and larger inverters add cost, and the battery bank is often the largest single line item. Off-grid totals can run from roughly the low five figures for a small cabin to $45,000 or more for a large one, so treat any range as a planning estimate and get at least two written local quotes.

DIY installation can cut labor costs for owner-builders comfortable with electrical work, but most jurisdictions still require permits and inspections. For national pricing by size, see How Much Do Solar Panels Cost in 2026?.

Grid-tied example math (assumptions: 20 kWh/day, 4.5 sun hours, 0.82 efficiency, 16.3¢/kWh, $3.00/W, 0.5% annual panel degradation, flat electricity rates, net metering or equivalent):

Panels: (20 ÷ 4.5) ÷ 0.82 ÷ 0.4 = 13.6, rounded up to 14 panels = 5.6 kW
Cost: 5,600 W × $3.00 = $16,800
Year-1 production: 5.6 kW × 4.5 × 0.82 × 365 ≈ 7,540 kWh, worth about $1,230 at 16.3¢
Simple payback: $16,800 ÷ $1,230 ≈ 13.7 years
25-year savings after degradation: about $12,200, before inverter replacement and without rate increases (rising rates would improve it)

What happened to the federal credit? From 2023 through 2025, the §25D credit covered 30% of solar panels and qualifying batteries (3 kWh or more) on a home you used as a residence, including a second home or cabin. The One Big Beautiful Bill Act (Public Law 119-21, signed July 4, 2025) ended it for expenditures after December 31, 2025, and an expenditure counts as made when installation is completed (IRS FAQ). A cabin system finished in 2025 is claimed on the 2025 return; unused credit carries forward. Our solar tax credit calculator explains what applies to your install date. This is not tax advice; confirm with a tax professional.

What is left? Cabins used for a farm or rural small business may qualify for USDA Rural Energy for America Program (REAP) support; funding rounds and eligibility vary, so check rd.usda.gov. Some states and co-ops run their own programs; check DSIRE and your state page before budgeting.

Solar vs utility company · 25-year comparison

25-year totals: 3%/yr rate increases, 0.5%/yr degradation, no federal credit. Methodology

Total utility payments

$29,750

Total solar cost (installed + remaining bills)

$17,590

Net savings

+$12,160

Avg. monthly difference

+$41/mo

See my savings →

Which Battery Type Is Best for a Log Cabin Solar System?

Lithium iron phosphate (LFP) is the best fit for most cabins because you can use 80–90% of its capacity and it lasts thousands of cycles. A common off-grid rule is to size the bank for 2–3 days of consumption, adjusted for usable depth of discharge (DoD): rated kWh = daily kWh × days ÷ usable DoD.

For a 10 kWh-a-day cabin with 2 days of autonomy:

Lead-acid (AGM), ~50% usable: 10 × 2 ÷ 0.5 = 40 kWh rated
LFP lithium, ~85% usable: 10 × 2 ÷ 0.85 ≈ 24 kWh rated

Rated battery capacity for a 10 kWh/day cabin (kWh). Lead-acid needs 40 kWh at 2 days and 60 kWh at 3 days; LFP needs 24 and 35. Formula: daily kWh x days / usable depth of discharge (AGM 50%, LFP 85%), rounded.

Chart summary: At the same autonomy, lead-acid needs about 1.7× the rated capacity of LFP (40 vs. 24 kWh at two days, 60 vs. 35 kWh at three). Add LFP’s much longer cycle life (about 3,000–6,000 cycles versus roughly 400–1,200 for AGM) and lithium is usually the lower-cost choice over 20 years, even though it costs more per rated kWh. Lead-acid banks often need replacement within 5–8 years and regular maintenance.

Cabins in overcast regions like the Pacific Northwest or Alaska typically need 3–4 days of autonomy or a backup generator. Choose a pure sine wave inverter and size it for surge loads, since well pumps can draw several times their running wattage at startup. Our battery bank size calculator walks through the calculation with your actual appliance loads.

Is Off-Grid Solar Worth It for a Log Cabin vs. Grid Extension?

If your cabin is far from existing power lines, off-grid solar often costs less over 25 years; if lines are close, connecting to the grid (and adding rooftop solar) is often cheaper. Line-extension costs vary widely by utility, terrain and distance, so get a written quote from your utility or electric co-op first.

Illustrative 25-year cost comparison for a mid-size cabin using 15 kWh/day (no federal credit)

Option	Upfront cost	Ongoing cost	Approx. 25-year total
Grid extension + utility power	$12,000 (example quote)	~$890/yr at 16.3¢, rising 3%/yr	~$44,500
Off-grid solar (10 panels + ~35 kWh LFP, 2 days)	~$22,000 (assumed)	~~$100/yr maintenance (assumed), plus one battery/inverter replacement (~~$8,000, assumed)	~$32,500

Assumptions: 15 kWh/day × 365 = 5,475 kWh a year × $0.163 = $892 in year one; utility spending grows 3% a year, giving about $32,500 in electricity over 25 years plus the $12,000 extension. The $12,000 line-extension figure, the $22,000 system price and the $8,000 replacement are example inputs, not market data. Replace them with your own quotes: at $30,000 or more for an extension the off-grid case gets much stronger, and at a few thousand dollars the grid usually wins.

Example 25-year cost, 15 kWh/day cabin (USD). About $44,500 for grid extension plus utility power versus about $32,500 for off-grid solar, using the stated example inputs and 3% annual rate growth at 16.3 cents per kWh.

Chart summary: Under these example inputs, off-grid solar comes out roughly $12,000 cheaper over 25 years because the $12,000 extension plus rising utility bills outweigh the battery replacement. The result flips if your extension quote is small, so the quote you obtain, not these placeholders, should decide.

Also weigh non-financial factors: off-grid systems keep running during grid outages (valuable in wildfire or storm-prone areas), but you manage batteries, winter production and backup power yourself. Sites with exceptional sun, such as Arizona and New Mexico, need fewer panels and fewer battery days. Use our solar payback calculator to model your scenario, including battery replacement and local utility rates.

Sources and Methodology

Sun-hour data: PVWatts Calculator and EIA solar resource overview
Tax-credit status: IRS FAQ on Public Law 119-21
Incentives: DSIRE and USDA Rural Development
Calculations: all panel counts, battery sizes and payback figures above are computed from the formulas and assumptions stated in each section. Prices, electricity rates and sun hours are assumptions; replace them with your own. See our methodology.

Frequently asked questions

Direct answers for US homeowners — sized for a $100/month electric bill.

How many solar panels do I need for a log cabin?

Use this formula: panels = (daily kWh ÷ peak sun hours) ÷ 0.82 ÷ 0.4 kW for 400 W panels. A weekend cabin using 3–5 kWh a day typically needs 2–4 panels; a year-round 1,000 sq ft cabin using 12–18 kWh needs 8–11; a full-time 1,200–1,500 sq ft cabin using 20–30 kWh needs 13–19. A 10 kWh/day cabin needs 7 panels at 5 sun hours but 9 at 3.5. Off-grid cabins without a generator should size for the lowest-sun month, which can require substantially more panels than the annual average suggests.

How much does it cost to power a log cabin with solar?

Is there a federal tax credit for cabin solar in 2026?

What size battery bank does an off-grid log cabin need?

Is off-grid solar cheaper than extending power lines to a cabin?

Same usage, bill-based guide

Your Log Cabin 2026 target maps to roughly a $100/month electric bill nationally.

$100 $100/month electric bill guide Panels · cost · payback · by state →

Popular state solar guides

Electricity rates and incentives vary — see data for your state.

CA California 33.25¢/kWh · 5.8h sun TX Texas 16.06¢/kWh · 5.6h sun FL Florida 15.3¢/kWh · 5.7h sun AZ Arizona 15.44¢/kWh · 6.5h sun NC North Carolina 14.94¢/kWh · 5.2h sun NY New York 29.38¢/kWh · 4.3h sun MA Massachusetts 30.14¢/kWh · 4.2h sun CO Colorado 16.72¢/kWh · 5.5h sun

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How these numbers were calculated

Electricity rate: 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).
Model: Version 2026.10 · 3%/yr electricity price escalation · 0.5%/yr panel degradation · simple payback = installed cost ÷ year-1 savings
Policy checked: September 29, 2026 · Full methodology · Report an error

Estimates only — not tax, legal or financial advice. Get at least three installer quotes and confirm incentives with your utility and a tax professional.