US residential solar · 2026 data

How Many Solar Panels Does a Weekend Cabin Need?

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

Multiply daily kWh by the days of backup you want, then divide by usable depth of discharge. For 2 kWh per day, two days of backup, and a lithium iron phosphate (LiFePO4) battery at about 85% usable capacity, you need roughly 4.7 kWh. Lead-acid batteries are generally limited to about 50% depth of discharge, so they need roughly twice the nominal capacity for the same usable energy. Add the loads that run while you are away, such as a refrigerator, when you total daily kWh.

Q: Is solar cheaper than a generator for a weekend cabin?

It depends on how often you visit. A generator costs less upfront, but you pay for fuel, oil changes, and repairs every hour it runs. Solar costs more upfront but has almost no fuel cost. To compare, divide your generator's yearly fuel and maintenance spend by the kWh it produces to get your cost per kWh, then compare the solar system's price over its expected life. Cabins used many weekends a year favor solar; cabins used a few times a year often favor a generator or a small portable power station.

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

Not for homeowners who buy a system in 2026. The 30% Residential Clean Energy Credit (Section 25D) ended for expenditures made after December 31, 2025, under the One Big Beautiful Bill Act. A system completed by that date can still be claimed on the 2025 return using IRS Form 5695, and unused credit can carry forward. Some third-party-owned systems may still qualify for a business credit, but that rarely applies to off-grid cabin kits. Check state and utility incentives and confirm with a tax professional.

Q: Does cabin solar work in cold, cloudy, or snowy climates?

Yes, with more panels. Cold air slightly improves solar panel efficiency, but shorter winter days and cloud cover reduce daily production, so cabins in the northern US need more array capacity for the same load. Snow covers panels temporarily; a steeper tilt helps it slide off, and panels should never be scraped with hard tools. If you use the cabin mostly in winter, size the system with winter sun-hour data from NREL PVWatts rather than annual averages.

1–4 kWh Typical daily load

1–4 Panels (400 W)

2–10 kWh Battery

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

Updated October 1, 2026 · 8 min read ·By Green Energy Calculators Editorial Team

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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.

Most off-grid weekend cabins need between one and six solar panels, but the right number depends on three things: how much electricity you use, how many peak sun hours your site gets in the season you visit, and how large a battery you pair with the array. A hunting cabin that only runs LED lights and phone chargers needs far less than a lake house running a refrigerator, a well pump, and a mini-split. This guide walks through the math, a regional table, battery sizing, costs, and the 2026 tax credit situation.

How to Calculate Solar Panels for a Weekend Cabin

Start with your daily energy use. List every appliance you will run on a typical day, multiply its wattage by the hours it runs, and add the results. That total is your daily load in watt-hours (Wh). Basic cabins often land near 1 kWh per day; cabins with a refrigerator, pump, and electronics can reach 3–4 kWh per day or more. For context, the U.S. Energy Information Administration reports that an average American home uses roughly 29 kWh per day, so even a well-equipped cabin is a fraction of that.

Next, find your site’s peak sun hours with the free NREL PVWatts calculator. One peak sun hour equals 1 kWh of sunlight per square meter, and annual averages in the contiguous US run from roughly 3.5 in cloudy northern areas to above 6 in the Southwest.

Then use this formula:

Array size (W) = daily Wh ÷ peak sun hours × 1.25

The 1.25 multiplier is a common planning allowance for wiring, charge controller, inverter, and battery losses, plus slow panel aging. NREL research on field data found median degradation of about 0.5% per year, so the allowance covers that comfortably. Divide the result by your panel’s wattage (most residential panels today are around 400 W) and round up.

Worked example: a cabin using 2,000 Wh per day at a site with 4.5 peak sun hours needs 2,000 ÷ 4.5 × 1.25 = 556 W. With 400 W panels, that rounds up to 2 panels. At 4,000 Wh per day, the same site needs about 1,111 W, or 3 panels.

Use our solar system size calculator to run your own numbers. For similar small-space builds, see our guides for a log cabin and a tiny house.

Cabin Solar Panels Needed by Region

Location changes your panel count by roughly a factor of two. The table below applies the formula above with 400 W panels. The sun-hour figures are rounded planning assumptions for each region’s annual average, not site data, so confirm your exact location in PVWatts.

Region	Planning peak sun hours	Array for 2 kWh/day	Panels (400 W)	Array for 4 kWh/day	Panels (400 W)
Desert Southwest (AZ, NM, NV)	6.5	385 W	1	769 W	2
Mountain West (CO, UT, ID)	5.5	455 W	2	909 W	3
Southeast (NC, TN, GA)	4.7	532 W	2	1,064 W	3
Midwest (WI, MN, MI)	4.2	595 W	2	1,190 W	3
Northeast (ME, VT, NY)	4.0	625 W	2	1,250 W	4
Pacific Northwest (WA, OR)	3.5	714 W	2	1,429 W	4

Solar Array Size Needed by Cabin Region (Watts). A 4 kWh/day cabin needs about 1,429 W in the Pacific Northwest vs. 769 W in the Desert Southwest. Source: calculated from planning sun hours; verify in NREL PVWatts 2026.

Chart summary: For the same load, a Pacific Northwest cabin needs about 86% more array capacity than a Desert Southwest cabin (714 W vs. 385 W at 2 kWh per day). A 4 kWh per day cabin ranges from about 770 W in the Southwest to about 1,430 W in the Northwest. Winter-only cabins should plan above these annual-average figures.

Annual averages hide seasonal swings. In northern states, December sun hours can fall to a fraction of the summer figure, and trees, steep terrain, and snow can cut output further. If you mainly use the cabin in winter, run PVWatts for your lowest-sun month and size to that, or add a panel as margin. For state-specific numbers, see our state solar data pages, such as North Carolina or Colorado.

What Battery Size Does an Off-Grid Cabin Need?

The battery covers evenings, cloudy days, and loads that run while you are away, such as a refrigerator. Use this formula:

Battery capacity (kWh) = daily kWh × days of backup ÷ usable depth of discharge

LiFePO4 lithium batteries are commonly planned at about 80–90% usable capacity, and many handle thousands of charge cycles, which is plenty for a cabin cycled a few dozen weekends a year. Lead-acid batteries should generally be discharged only to about 50%, so they need roughly double the nominal capacity. Check your battery’s datasheet for its rated usable capacity and its minimum charging temperature, since lithium cells should not be charged below freezing unless the battery has built-in heating.

Worked example: 2 kWh per day × 2 days ÷ 0.85 = 4.7 kWh of LiFePO4 storage.

LiFePO4 Battery Capacity Needed (kWh). A 4 kWh/day cabin needs about 9.4 kWh for two days of backup at 85% usable capacity. Source: calculated with the battery sizing formula above.

Chart summary: Battery size scales directly with both load and backup days. A 1 kWh per day cabin needs about 1.2 kWh for one day of backup, while a 4 kWh per day cabin needs about 9.4 kWh for two days. Doubling your backup days doubles your battery size, so decide how many cloudy days you are willing to ride out before you buy.

Panels and batteries work as a pair. More panels refill the battery faster after a cloudy stretch; a larger battery lasts longer between sunny days. In cloudy regions, spend on both. Our battery storage calculator helps size them together.

What Does Cabin Solar Cost in 2026, and Is There a Tax Credit?

Cabin solar prices vary widely with system size, battery capacity, brand, and whether you install it yourself, so we do not quote a single number. The main cost drivers are:

Battery: usually the largest single line item for an off-grid cabin
Solar panels and mounting: roof, ground, or pole mounts
Inverter/charger and charge controller: sized to your largest simultaneous load
Wiring, breakers, and disconnects: required for safety and code compliance
Labor and permits: if you hire an installer; many jurisdictions require permits and electrical inspection even for off-grid systems

Ask every installer or kit seller for an itemized quote, because two bids for the same array can differ mostly by battery size.

Tax credit update: the 30% federal Residential Clean Energy Credit (Section 25D) is no longer available for systems bought in 2026. Under the One Big Beautiful Bill Act, it ended for expenditures after December 31, 2025. Systems completed by that date can still be claimed on a 2025 return with IRS Form 5695, and unused credit can carry forward. Older guides that cite “30% through 2032” are out of date. Look for state, utility, or local incentives instead, and confirm details with a tax professional.

If you want a prebuilt option, Shop Solar Kits^† sells off-grid solar kits (affiliate link; check current pricing and the coupon code WAYSENG101 at checkout). Compare any kit’s usable battery capacity and inverter rating against your calculated load before buying.

Off-Grid Solar vs. Grid Extension vs. Generator

The right power source depends on distance from the grid and how often you visit.

Grid extension: if the cabin is far from the nearest utility line, running new service can cost tens of thousands of dollars, depending on distance, terrain, and your utility’s rules. Ask the utility for a written estimate. If a grid connection is close, a grid-tied system with net metering may make sense; rules vary by utility and state, so check our net metering calculator.

Generator: upfront cost is lower, but you pay for fuel, maintenance, and noise every hour it runs. To compare fairly, estimate the generator’s fuel use per hour (check your model’s specification at your typical load), multiply by fuel price and annual run hours, add maintenance, and divide by the kWh produced. Then compare that cost per kWh against a solar system’s total price spread over its expected life.

Solar plus battery: best for remote cabins, frequent use, and quiet, fuel-free power. For a cabin used only a few times a year, a generator or portable power station can be the more economical choice. Use the solar payback calculator to test your own usage and costs.

Sources

NREL PVWatts Calculator (site-specific solar production and sun hours): pvwatts.nrel.gov
NREL, “Photovoltaic Degradation Rates: An Analytical Review” (median degradation about 0.5% per year): nrel.gov
U.S. Energy Information Administration, average household electricity use: eia.gov
IRS, Form 5695 and the Residential Clean Energy Credit: irs.gov