A typical U.S. home uses about 29 kWh of electricity per day, but a well-designed tiny house can run on a fraction of that—often 2–6 kWh daily if you’re conscious about loads. That gap is massive, and it’s why sizing solar for a tiny home is both doable and worth getting right. Pick too small a system and you’ll be rationing power, babysitting batteries, and running a generator every cloudy stretch. Oversize it and you’ll spend more than you need and wrestle with where to put the panels. I’ve helped size arrays for cabins and tiny homes in every kind of climate, and the same principles keep showing up. You’ll see how to estimate your daily use, translate it into an array and battery size that actually works in winter, choose the right voltage and inverter, and plan for real-world hiccups like shading and snow. The goal: a system that quietly powers your life without drama.
Quick Answer
Most tiny houses do well with a 1.5–3 kW solar array and 5–12 kWh of lithium battery storage if you use gas for heat/cooking and keep loads efficient. All-electric setups (induction, mini‑split, electric water heat) often need 3–5 kW of panels and 10–20 kWh of storage, especially in cloudy or northern locations. Size your array using your worst‑month peak sun hours and include a 20–30% margin for losses.
Why This Matters
Getting the solar size right is the difference between a tiny house that feels seamless and one that constantly runs out of juice. Picture a cold January week: your fridge and mini‑split run longer than usual, the days are short, and snow covers part of the array. If your system is undersized, you’ll drain the batteries to protect the compressor, fire up a generator, and still risk premature battery wear.
On the flip side, aimlessly oversizing isn’t free. Larger arrays need more roof or ground space, stronger mounts, and bigger balance‑of‑system gear. Batteries that never cycle deeply can last a long time, but buying twice the capacity you’ll never use locks up budget that could go to insulation, a higher‑efficiency heat pump, or better sealing—upgrades that permanently reduce daily kWh.
Real-world example: A 200 sq ft tiny house in Denver using 4 kWh/day with 4.8 winter sun hours can be comfortable on ~1.2–1.6 kW of panels. Move that same house to Seattle at ~2 winter sun hours and it needs ~2.4–3.2 kW to keep pace, or a backup plan. Location and season matter more than the “tiny” label.
Step-by-Step Guide
Step 1: Audit your loads like a pro
Write down every electrical device, its watts, and hours used per day. Don’t guess—measure with a plug‑in watt meter or read nameplates and real duty cycles. You might find what size solar system to generate electricity for a tiny house kit helpful.
- Fridge: 60–150 W, ~8–12 hours/day cycling (0.6–1.2 kWh).
- Mini‑split: 300–800 W average in mild weather, 1–4 kWh/day depending on climate.
- Lighting: LED strips or bulbs, 20–60 W total, 0.2–0.6 kWh/day.
- Cooking: Induction can hit 1,800 W; actual daily use varies widely (0.3–2 kWh).
- Electronics: 50–200 W total, 0.2–0.6 kWh/day.
Add up a typical day and a worst‑case winter day. Many efficient tiny homes land at 2–6 kWh/day; all‑electric ones can hit 6–10 kWh/day in cold months.
Step 2: Use peak sun hours to size panels
Find your location’s peak sun hours (PSH) for the worst month. Winter PSH varies: Phoenix ~5–6, Denver ~4–5, New York ~2.5–3.5, Seattle ~1.5–2.5. Panels don’t output their rated wattage all day; you’ll lose energy to temperature, wiring, inverter, and charge inefficiency.
- Formula: Array size (kW) = Daily kWh / (PSH × system efficiency).
- Use 0.75–0.80 as a realistic efficiency factor.
- Example: 4 kWh/day, 3 PSH, 0.75 efficiency → 4 / (3 × 0.75) ≈ 1.78 kW.
- Add 20–30% margin for cloudy stretches and aging.
Step 3: Size batteries for autonomy and longevity
Decide how many days you want to ride out poor sun (1–3 days is common). Account for usable depth of discharge (DoD) and round‑trip efficiency.
- Lithium LiFePO4: ~90% DoD usable, ~95% efficient.
- Lead‑acid: ~50% DoD recommended, ~80–85% efficient.
- Formula (lithium): Storage (kWh) = Daily kWh × days / 0.90.
- Example: 4 kWh/day × 2 days / 0.90 ≈ 8.9 kWh storage.
In cold climates, insulate the battery compartment and keep charge temps within spec. Lithium charging is restricted below freezing unless heated. You might find what size solar system to generate electricity for a tiny house tool helpful.
Step 4: Choose voltage, inverter, and charge controller
Higher system voltage reduces current and cable size.
- Up to ~2 kW: 24 V can work; beyond that, 48 V is smoother.
- Inverter: Size for continuous load plus surge. Many tiny homes use 2–3 kW inverters with 2× surge for tools, pumps, or microwave starts.
- MPPT charge controller: Match open‑circuit voltage (Voc) and short‑circuit current (Isc) of your array; leave a cold‑weather voltage margin.
Group panels in strings that fit the controller’s voltage window and keep wiring runs short with proper gauge.
Step 5: Plan mounting, tilt, and shading
Roof area on a tiny house is finite. A common 400 W panel is roughly 6.5 ft × 3.25 ft (~21 sq ft). Six panels (2.4 kW) need ~126 sq ft, plus spacing and walkway.
- If your roof orientation or shading is poor, consider a ground mount or adjustable tilt rack.
- Snow country: Steeper tilt (35–45°) sheds snow and boosts winter yield. Clear panels promptly; 1 cm of snow can drop output to near zero.
- Vent clearances and skylights may dictate panel placement—plan wiring paths and penetrations carefully.
Step 6: Include a backup and energy discipline
Even well‑sized off‑grid systems hit rough patches. A small inverter generator (1–2 kW) and a smart charger can save batteries on multi‑day storms. You might find what size solar system to generate electricity for a tiny house equipment helpful.
- Program low‑voltage cutoffs and charging profiles correctly for your chemistry.
- Use load‑shifting: run high‑draw appliances on sunny afternoons when the array can carry the load and top batteries.
- Track daily kWh with your inverter’s monitor to catch creeping loads early.
Expert Insights
Professionals see two patterns over and over: underestimating winter and overestimating panel output. Panel wattage is a nameplate, not a promise; temperature, angle, dirt, and clouds shave off real production. If your worst‑month peak sun hours are 2.5, a 2 kW array might only deliver 3–4 kWh/day once losses are counted.
Another misconception is “tiny house equals tiny system.” If you heat, cook, and make hot water electrically, your daily demand jumps fast. A mini‑split is efficient, but a resistance space heater or tank water heater will devour kWh. A heat pump water heater, induction used thoughtfully, and good insulation can cut total demand by 30–50% compared to brute‑force resistance heat.
Roof orientation matters more than most people think. A due‑east or due‑west roof can drop production ~10–20% versus south, even with identical panel counts. In snowy regions, ground mounts outperform simply because they’re easier to keep clean and at a winter‑friendly tilt.
Pro tip: pick 48 V for systems over ~2 kW; you’ll have cooler cables, smaller breakers, and happier charge controllers. And bake in a 20–30% capacity cushion—cheaper than buying a generator later and kinder to your batteries long term.
Quick Checklist
- List every appliance with watts and daily hours; calculate daily kWh and a winter worst case.
- Find worst‑month peak sun hours for your location and use 0.75–0.80 system efficiency in calculations.
- Add a 20–30% margin to array size to cover clouds, dirt, and aging.
- Size lithium batteries for 1–3 days of autonomy at ~90% usable DoD; insulate and heat if in freezing climates.
- Choose 48 V for arrays larger than ~2 kW to reduce current and wire size.
- Select an inverter with enough surge capacity for compressors, pumps, and tools.
- Plan panel placement for tilt, snow shedding, and shading; consider a ground mount if the roof is sub‑optimal.
Recommended Tools
Recommended Tools for what size solar system to generate electricity for a tiny house
Frequently Asked Questions
Can a tiny house run air conditioning on solar?
Yes, but size accordingly. A high‑efficiency mini‑split might average 300–700 W in mild weather, but can draw 1–1.5 kW during hot afternoons. If you plan to cool daily, aim for a 3–4 kW array and 10–15 kWh of storage, and use load‑shifting to run hardest when the sun is strong.
How many panels can I fit on a typical tiny house roof?
It depends on roof size and obstructions, but many tiny homes can fit 4–6 panels. With 400 W panels at ~21 sq ft each, six panels (2.4 kW) need roughly 126 sq ft of clear space. Dormers, vents, and skylights reduce usable area; a ground mount often adds capacity and better orientation.
What’s the difference between grid‑tied and off‑grid sizing?
Grid‑tied systems can be smaller because the grid covers shortfalls; a 1.5–3 kW array may offset much of a tiny home’s use. Off‑grid needs to meet demand in the worst month and include storage and a backup plan, so 2–5 kW arrays and 8–20 kWh of batteries are common depending on loads and location.
How reliable is solar in winter for northern states?
It works, but you must design for low sun and snow. Winter peak sun hours can drop to 2 or less, and snow coverage kills production. Steeper tilt, aggressive snow clearing, a 20–30% oversize factor, and a small generator make an off‑grid winter setup reliable instead of stressful.
What does a system like this cost?
Ballpark costs vary widely. A 2 kW array with a quality 48 V inverter/charger and ~10 kWh of LiFePO4 storage might run $8,000–$15,000 in parts, plus mounting and wiring. A ground mount, larger battery, or premium components can push it higher; DIY labor reduces cost if you’re experienced.
Do I need permits for a tiny house solar system?
If you’re off‑grid and mobile, you may not need formal permits, but local rules still apply for electrical safety and anchors. Stationary installs typically require electrical permits and inspections. Even when not legally required, following code practices (correct wire gauge, breakers, bonding) is smart.
Conclusion
Tiny houses thrive on right‑sized solar: tally your real daily kWh, design to winter’s worst sun, and add a cushion so the system glides through cloudy spells. For many, that means 1.5–3 kW of panels with 5–12 kWh of lithium storage; all‑electric homes bump higher. Next step: do a load audit, check your location’s peak sun hours, and sketch an array and battery plan. Build in room for growth and consider a small backup generator. With those pieces in place, your tiny house runs quietly and reliably on sunshine.
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