🏠 Tiny House Solar Systems

Tiny House Solar Calculator:
THOW, Container, Foundation + ITC Credit

The only tiny house solar tool with house-type roof feasibility check, propane and wood stove energy offsets, well pump load, composting toilet fan, and 30% federal tax credit shown on every result. Works for THOW, stationary foundation, shipping container, and cabin builds.

☕ Design Your Tiny House System

Step 1 — Select Your Build Type
Fixed foundation or pier. Full roof access. Typically 16-24 ft long. Typical usable roof: 120 sq ft.
Step 2 — Select Your Appliances
Appliance Watts Hrs
❄ Essentials
💻 Work and Entertainment
🍳 Kitchen and Laundry
🌢 Heating, Water and Utilities
Total Daily Load
High-watt loads: 0W peak | Need inverter for AC loads
— kWh/day
Step 3 — Location and Autonomy
hrs/day
Peak sun hours by region: Southwest AZ/NM 6.0-7.0 / CA central 5.5 / Texas 5.0 / Southeast 5.0 / Midwest 4.5 / Pacific NW 3.5-4.0 / New England 4.0 / Mountain CO 5.5. Use NREL's PVWatts tool for your exact address.
Step 4 — Components
Step 5 — Energy Offsets
kWh/day
kWh/day
Propane offset: Cooking on a 2-burner propane stove instead of electric saves roughly 0.5-1.5 kWh/day. A propane or wood stove for winter heat instead of an electric mini-split can save 1-5 kWh/day in cold climates. Enter the electrical equivalent you are replacing.

☀ Your Tiny House Solar System

🏠

Select your build type, appliances, and offsets for propane or wood stove. Hit Calculate to see your complete 4-component system with the 30% federal tax credit applied.

Why Tiny House Solar Sizing Is Different from Regular Home Solar

A standard residential solar installation is sized to offset your utility bill and can always pull from the grid when production falls short. A tiny house solar system — especially for a THOW or off-grid stationary build — has to function as a complete standalone power plant. There is no grid to fall back on at two in the morning when the batteries are low after three cloudy days. Every load matters, every offset matters, and the roof area available to you is often brutally limited.

The biggest mistake people make when sizing a tiny house solar system is borrowing the logic from RV or van calculators. An RV is used for weekends and vacations — it can tolerate some discomfort, shore power is always nearby, and loads are minimal. A tiny house is your home. You have a full refrigerator running 24 hours a day, you work from home on a laptop eight hours a day, and if you have a well pump, that thing runs every single time anyone washes dishes. These are full residential loads packed into a small building.

The second big mistake is ignoring what you are NOT using electricity for. Many tiny house builders use propane for cooking and sometimes for winter heat. This is a massive electrical load offset that completely changes the system size. A propane two-burner stovetop that you cook three meals a day on is saving you roughly 0.8-1.5 kWh of electrical equivalent per day — the size of one or two solar panels worth of daily production. Our calculator is the only tiny house solar tool that lets you enter this propane offset and see it reduce your system size in real time.

THOW vs Stationary: How Roof Area Changes Everything

A tiny house on wheels (THOW) typically has a roof that is about 8 to 8.5 feet wide and 20 to 24 feet long. After accounting for the loft overhang, the HVAC unit if present, and the structural ridge beam, you typically have 40 to 60 usable square feet for solar panels. That is roughly the same as a cargo van roof — constrained but workable if your loads are disciplined. A 24-foot THOW with a clear roof and good south exposure can physically fit 4 to 5 x 200W semi-flexible panels, for a total of 800W to 1,000W.

A stationary tiny house on a foundation has much better options. You can use standard 300W to 400W rigid panels in a ground-mount array next to the house if the roof is too steep or shaded. A shipping container home has the best solar surface of all — the flat metal roof of a 40-foot container offers up to 135 usable square feet for panels, and 500W bifacial panels mounted directly on the metal roof are an increasingly popular configuration.

How the Tiny House Solar Calculator Works

The tool takes your appliance loads, subtracts any propane or grid offsets, adds system losses (inverter efficiency for AC loads, battery round-trip efficiency, wiring losses), and works backward to find the solar array size that can replace what you need per day at your location’s average peak sun hours. It then checks whether that array physically fits on your roof type and tells you whether a ground mount is recommended. The four component outputs — panels, battery bank, charge controller, and inverter — plus the 30% ITC calculation give you everything you need to request quotes from installers or order components yourself.

Three Real Tiny House Solar Examples

🚗

Minimal THOW — Off-Grid in New Mexico

Socorro County, NM | 6.5 peak sun hours | LFP batteries | Propane cooking

Sarah built her 24-foot THOW in 2023 and parked it on five acres outside Socorro. She works remotely as a graphic designer, uses propane for cooking and a wood stove for winter heat, and has kept her electrical loads intentionally minimal to make off-grid living viable on a tight budget.

ApplianceWattsHrs/DaykWh
12V compressor fridge45W241.08
LED lighting25W40.10
Laptop (remote work)65W80.52
Phone + hotspot35W40.14
Composting toilet fan7W240.17
Total2.01 kWh/day
Propane offset (cooking): -0.8 kWh. Net solar: 1.21 kWh/day. At 6.5 sun hrs, 3-day autonomy, LFP: 2 x 200W semi-flex panels on THOW roof (0.4 kW, 13.6 sq ft vs 55 sq ft roof) | 100Ah LFP (1.2 kWh) | 20A MPPT | No inverter needed (all DC loads). Gross: $2,800 | After 30% ITC: $1,960. Roof at 25% use — well within limits.
💼

Work-From-Home Foundation Build — Vermont

Stowe, VT | 4.0 peak sun hours | LFP batteries | Mini-split heat pump

Marcus built a 200 sq ft stationary tiny house on a permanent foundation in Vermont and uses it year-round as his primary residence. He works from home as a software developer and needs reliable power for multiple monitors, a NAS drive, and a mini-split for both heating and cooling. No propane — fully electric.

ApplianceWattsHrs/DaykWh
Refrigerator45W241.08
Laptop + monitor + NAS130W81.04
Mini-split heat pump (avg)600W53.00
Washing machine400W10.40
LED lighting + fans55W60.33
Internet + devices50W241.20
Total7.05 kWh/day
No propane offset. Net solar at 4.0 sun hrs, 3-day autonomy, LFP: 8 x 300W rigid panels = 2.4 kW (112 sq ft vs 120 sq ft — tight, so 3 go on a small south-facing ground mount) | 600Ah LFP @ 12V (7.2 kWh usable) | 60A MPPT | 3,000W pure sine inverter for AC loads. Gross: $14,200 | After 30% ITC: $9,940. Vermont’s low sun hours (4.0 avg) and high heating load make this a larger system than Southwest equivalents.
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Container Home — Texas Hill Country

Wimberley, TX | 5.0 peak sun hours | LFP batteries | Well pump included

The Garcias converted a 40-foot shipping container into a 320 sq ft off-grid residence on their 10-acre property outside Wimberley. They have a drilled well (50 ft depth, 1/2 HP submersible pump), use propane for cooking, and have a 24V system to manage the longer cable runs from their panel array on the container roof.

ApplianceWattsHrs/DaykWh
Refrigerator/freezer (12V)70W241.68
Well pump (1/2 HP, 3 cycles)750W0.50.38
Mini-split AC (TX summer)800W64.80
LED lighting + fans60W60.36
Laptop + devices + internet100W101.00
Total8.22 kWh/day
Propane cooking offset: -1.0 kWh. Net: 7.22 kWh. At 5.0 sun hrs, 3-day autonomy, LFP @ 24V: 5 x 500W bifacial on container roof (2.5 kW, 92 sq ft vs 135 available — 68% use) | 400Ah LFP @ 24V (9.6 kWh) | 60A MPPT | 4,000W inverter for AC. Gross: $19,500 | After 30% ITC: $13,650. Well pump adds significant peak-demand requirement — size inverter for 750W minimum surge rating.

3 Expert Tips for Tiny House Solar Design

1

Start With Loads, Not Panels

Almost every beginner mistake in tiny house solar involves buying panels first and calculating loads second. The result is almost always a mismatched system — too much solar for the battery bank, or a battery bank that cannot store what the panels produce. Start with your true daily load in kWh/day, calculated appliance by appliance with realistic hours of use. Only then size your panels and battery to cover that load. Switching a resistive electric water heater to a propane on-demand unit can reduce your daily load by 0.5-1.5 kWh and save you $1,000-$2,000 in battery bank costs — more than the propane heater costs.

2

LFP Batteries Pay for Themselves in a Tiny House

AGM batteries are tempting because they cost about half as much upfront per kilowatt-hour. But AGM only gives you 50% usable capacity versus 90% for LFP, meaning you need twice as many AGM cells to store the same usable energy. AGM batteries in a tiny house will typically need full replacement in 3-5 years under regular use. LFP batteries regularly last 10-15 years in the same application. When you do the lifetime cost math for a tiny house that you plan to live in for years, LFP is almost always cheaper per kilowatt-hour delivered over the life of the system.

3

Claim the 30% ITC — Even on a THOW

The IRS Residential Clean Energy Credit (formerly the Investment Tax Credit) applies to solar installations on your primary or secondary residence. A properly documented tiny house on wheels can qualify if it has sleeping, cooking, and toilet facilities and is your primary residence. The 30% credit applies to the full system cost — panels, batteries, inverter, charge controller, and installation labor. On a $10,000 system that is a $3,000 direct reduction in your federal tax liability. Unused credit carries forward to future tax years. File IRS Form 5695 with your tax return and keep all receipts. Always confirm eligibility with a tax professional familiar with alternative housing.

16 Frequently Asked Questions About Tiny House Solar

How many solar panels does a tiny house need?+
The range is wide — from 2 x 200W panels (0.4 kW) for a minimalist THOW with propane cooking and no AC, to 8-12 x 300-400W panels (2.4-4.8 kW) for a fully electric stationary tiny house in a cloudy climate with electric heat and a well pump. The most common off-grid tiny house systems fall in the 1.2-3.0 kW range, covering typical loads of 3-8 kWh per day at 4-6 peak sun hours. Use this calculator with your actual appliances to find your specific requirement rather than relying on rules of thumb.
Can I run a well pump on solar?+
Yes, but it requires careful sizing. A standard 1/2 HP submersible well pump draws about 750 watts while running, with a startup surge of 1,500-2,000 watts for 1-2 seconds. Your inverter must be rated to handle this surge — a 2,000W inverter with 4,000W peak surge capacity is the minimum for a 1/2 HP pump. The good news is that well pumps typically run in short cycles (5-15 minutes) several times per day, so the daily kWh consumption is much lower than the peak wattage suggests. Most tiny house builders with wells run their pump 2-4 kWh per week, which is a manageable load. Include the well pump in your appliance list in our calculator and let it run at 750W for 0.5 hrs/day as a starting estimate, then adjust based on your actual water usage.
Does the 30% solar tax credit apply to tiny houses?+
It can, if your tiny house qualifies as a dwelling unit. The IRS defines a qualifying home as one that provides basic living accommodations — sleeping area, kitchen, and toilet. A THOW with a loft bed, a kitchen, and any toilet (composting or plumbed) generally meets this definition when used as your primary residence. The credit applies to the solar panels, battery storage, inverter, charge controller, and installation costs. File IRS Form 5695. There have been no rulings specifically excluding tiny houses on wheels or shipping container homes from the credit, but the qualification of your specific home should be verified with a tax professional. See the current guidance at IRS.gov.
How big a battery bank does a tiny house need?+
For a minimal THOW using 2-3 kWh per day, 2-3 days of LFP autonomy means a 200-300Ah LFP battery bank at 12V (2.4-3.6 kWh usable). For a fully electric stationary tiny house using 6-8 kWh per day with 3-day autonomy, you might need 400-600Ah LFP at 24V (9.6-14.4 kWh usable). The most important principle: never size your battery bank without specifying the number of autonomy days first. A 2-day autonomy system is fine if you have a generator backup or can tolerate load shedding during cloudy periods. A 5-7 day system provides true independence in cloudy climates but costs significantly more upfront.
Should I use 12V or 24V in a tiny house?+
For THOW and small stationary builds under about 1.5 kW of solar, 12V is simpler and more compatible with RV accessories and 12V DC appliances. For larger systems (2 kW+ solar, 300Ah+ battery banks), 24V is more efficient because it halves the current for the same power, reducing wire size and losses. Shipping container homes, which often run larger systems and have longer cable runs from roof panels, frequently use 24V or even 48V. If you ever plan to expand significantly, start at 24V — you cannot mix 12V and 24V batteries in a bank without a converter.
Can I run a mini-split on solar in a tiny house?+
Yes, but it is the largest load most tiny house owners will ever run on solar. A 9,000 BTU mini-split draws about 700-900 watts running, with a startup surge of 1,500-2,500 watts. In a hot climate running 8-10 hours per day in summer, that can be 5-8 kWh per day from this one appliance alone — more than everything else combined. You need an appropriately sized inverter (minimum 3,000W rated, 5,000W surge) and a battery bank large enough to run through the night without full recharge. Many tiny house owners in moderate climates use the mini-split only for cooling (2-4 hours/day), not heating, and use a wood stove or propane for winter heat instead. This dramatically reduces the battery and panel requirement.
What is the benefit of propane for a solar tiny house?+
Propane eliminates the two largest electrical loads in most tiny houses: cooking and winter heating. A two-burner propane stove eliminates the need for an electric cooktop (1,200-3,000W) or microwave as a primary cooking method. A propane on-demand water heater eliminates the electric tankless water heater (1,400-3,000W). A propane wall heater or the old-fashioned woodstove eliminates the mini-split’s heating mode. Together, these offsets can reduce your daily electrical load by 3-8 kWh in winter, cutting your required battery and solar capacity roughly in half. The tradeoff is propane fuel cost and the complexity of having two energy systems, but for off-grid tiny house living in most of the US, the hybrid propane-solar approach is both more reliable and more cost-effective than trying to go fully electric on a limited roof area.
What type of solar panels work best on a THOW?+
Semi-flexible or thin-film panels are the standard for THOW roofs. They are typically 100-200W, mount flush to the roof without rails (reducing height and wind resistance for highway travel), and are lighter than rigid panels. Semi-flexible panels bend slightly to conform to a slightly curved or angled roof surface. The tradeoff versus rigid glass panels is efficiency (semi-flex runs 15-20% efficiency vs 21-23% for premium rigid monocrystalline) and lifespan (semi-flex warranties are typically 5-10 years vs 25 years for quality rigid panels). For a stationary tiny house that never moves, rigid monocrystalline panels on proper mounting rails are almost always the better choice per dollar of energy produced over the life of the system.
Do I need a permit for tiny house solar?+
This depends entirely on your county and whether your tiny house is considered a permanent structure. Solar on a THOW (registered as an RV or vehicle) often requires no permit, similar to how adding solar to a camper van needs no permit. Solar on a tiny house on a permanent foundation is treated like residential solar and typically requires an electrical permit and sometimes a building permit. Most counties that have adopted the NEC require the work to be done by a licensed electrician and inspected. Some rural counties in the Southwest and Mountain West have minimal permit requirements for off-grid structures. Contact your county building department or visit your state’s contractor licensing board website. Installing without required permits can affect your ability to get homeowner’s insurance and can create issues if you ever sell the property.
What charge controller should I use?+
MPPT (Maximum Power Point Tracking) controllers are standard for any tiny house system. They extract 10-30% more energy from panels than older PWM controllers, especially in cold weather and partial shade. The most popular choice among tiny house builders is the Victron SmartSolar MPPT series, which includes Bluetooth monitoring, LFP battery profiles, and excellent reliability. Size the controller for your total panel wattage divided by your system voltage, then add 25% safety margin. A 1,200W array at 12V needs a 12V controller rated for at least 100A theoretical max (1,200/12=100A) — but since MPPT controllers connect at the panel’s open-circuit voltage (typically 30-40V for one panel), the actual input current is much lower. The controller datasheet will specify the maximum input watts — confirm your array falls within that limit.
How do I monitor my tiny house solar system?+
A battery monitor is non-negotiable for off-grid living. The Victron BMV-712 ($130-$160) shows battery state of charge, voltage, current in and out, and estimated time to empty or full. It connects via Bluetooth to the Victron Connect app on your phone, giving you real-time data from anywhere in or around the house. For a complete system overview, the Victron CCGX or Cerbo GX touch display shows panel production, battery state, and load simultaneously. Many tiny house builders also use the Victron VRM cloud portal to monitor their system remotely — useful when you are away from your property or want to check your battery level before heading home. Track your daily production and consumption for the first month to find any hidden loads and optimize your usage patterns.
What is a pure sine wave inverter and do I need one?+
A pure sine wave inverter produces AC power that is identical in quality to what the utility grid delivers. Most modern appliances — laptops, chargers, mini-splits, washing machines, and anything with a motor or compressor — require pure sine wave AC to operate correctly and safely. Modified sine wave inverters (the cheaper option) produce a choppy approximation of AC that can cause overheating in motors, buzzing in audio equipment, and reduced efficiency in chargers. Never use a modified sine wave inverter for a mini-split heat pump, refrigerator compressor, or well pump — the motor damage risk is real. The price premium for pure sine wave ($50-$200 more depending on size) is worth it for any appliance that will run regularly on solar. Budget brand pure sine wave inverters (Giandel, Ampeak) are fine for occasional use. Victron and SMA inverters are worth the premium for daily primary residence use.
How do I handle cloudy days and winter in the Pacific Northwest?+
The Pacific Northwest averages 3.5-4.0 peak sun hours per day, with winter months dropping to 2.0-2.5. Full off-grid living in western Oregon or Washington on solar alone requires either a very large system (4-6 kW+ with 5-7 day battery backup) or a hybrid approach with a generator. Most PNW tiny house dwellers use a generator backup: a small 2,000-3,000W gas or propane generator that runs 1-2 hours on the darkest winter days to top up the battery bank. Sized correctly, this uses less than 2 gallons of gas per week even in the worst winter months. For the summer months (June-September), the Pacific Northwest has excellent production with long daylight hours. A well-sized system that works in summer with 3-day autonomy will need supplemental generation maybe 20-30 days per year in the deep PNW winter.
Can I expand my tiny house solar system later?+
Yes, with planning. The most future-proof approach is to design at 24V from the start (even if your initial load could run on 12V), because 24V gives you more room to add panels and batteries without hitting the limits of your charge controller. Size your charge controller for the array you plan to have eventually, not just today — buying a 60A MPPT when you only have 20A of panels today costs a little more upfront but avoids replacing the controller when you expand. LFP batteries can be added in parallel (same voltage, same brand/model recommended) to increase capacity. Most MPPT controllers can handle additional panels wired in parallel without problems up to their rated wattage. The one thing you cannot easily expand is your physical roof — so think through your maximum panel capacity before you start and plan your DC wiring to support it.
What is a composting toilet and how much power does it use?+
A composting toilet is a waterless toilet that decomposes organic waste aerobically using a small internal fan and sometimes a heater element. Popular brands for tiny houses include Nature’s Head, Sun-Mar, and Separett. The fan runs continuously (24 hours a day) and draws 7-12 watts — about 0.17-0.29 kWh per day. Some models have a heating element that activates in cold weather, adding 25-50 watts for several hours per day. The advantage for tiny house solar is huge: eliminating the need to pump out a septic tank or connect to municipal sewer, while only drawing about as much power as a LED nightlight. The Sun-Mar Excel uses 120V AC (45W continuous fan) and adds more load; the Nature’s Head uses a 12V DC fan (5-7W) and is preferred for off-grid systems.
Is solar a good investment for a tiny house?+
For an off-grid tiny house where the alternative is running utility power lines (which can cost $10,000-$50,000+ to extend to a remote property) or running a generator full-time ($200-$500/month in fuel), solar pays back extremely quickly — often in 1-3 years. For a THOW that parks at locations with shore power most of the time, solar is more of a convenience and fuel savings device — the payback period is longer but you gain the freedom to park anywhere. The 30% federal tax credit significantly improves the economics for any tiny house that qualifies. For tiny houses on urban or suburban lots where utility hookup is feasible, the ROI calculation depends more on your specific electricity rates and solar production than on avoided hookup costs.

Related Solar and Energy Calculators

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Legal Disclaimer and Editorial Transparency

The Tiny House Solar Calculator on USCalculators.com provides estimates for educational and planning purposes only. All outputs are based on standard solar engineering methodologies and the load data you provide. Actual system performance depends on your specific location, panel orientation, shading, temperature, component efficiency, and real-world usage patterns.

The 30% Residential Clean Energy Credit (ITC) calculation shown is an estimate based on the current credit rate as of 2024. Tax eligibility for tiny house solar depends on your specific situation including how the dwelling is classified, how it is used, and your individual tax liability. Always consult a qualified tax professional before making financial decisions based on expected tax credits. See current IRS guidance at IRS.gov Form 5695.

Peak sun hours data is provided as general regional estimates. For precise values at your location, use the NREL PVWatts Calculator. Propane energy equivalents are approximations. Well pump loads vary by pump depth, water table, and cycle frequency.

Editorial policy: USCalculators.com is an independent educational resource. We have no affiliate relationships with solar equipment manufacturers, tiny house builders, or tax professionals.