Solar Power for a Tiny House
By Matt · Updated
The short answer
A full-time tiny house typically lands between 2 and 5 kWh a day, which is a system of roughly 1 to 2 kW of panel and 5 to 10 kWh of storage. Roof area is the binding constraint rather than budget, which is what makes cooking and heating with electricity the decision that breaks these builds.
The worked system
A tiny house lived in full time by one or two people. Propane for cooking and hot water, wood or propane for heat. Electricity does lighting, refrigeration, water, and devices.
Daily loads
| Load | Watts | Hours | Duty | Wh/day |
|---|---|---|---|---|
| Refrigerator (compact) | 120 | 24 | 0.35 | 1,008 |
| LED lighting ×6 | 8 | 5 | 1 | 240 |
| Water pump | 60 | 0.75 | 1 | 45 |
| Laptop | 45 | 6 | 1 | 270 |
| Wifi router | 12 | 24 | 1 | 288 |
| Phone and device charging | 15 | 3 | 1 | 45 |
| Ventilation fan | 25 | 6 | 1 | 150 |
| Washing machine (compact) | 400 | 0.5 | 1 | 200 |
| Total | 2,246 Wh | |||
What that needs
- Solar array
- 802 W
- Battery bank
- 292 Ah at 24 V
- Usable storage
- 4.5 kWh
- Charge controller
- 42 A minimum
- Inverter, continuous
- 1,000 W
- Must also surge to
- 1,525 W
An inverter has two ratings and both have to hold. The continuous figure covers everything running at once; the surge figure covers the largest motor starting on top of that, for a few seconds. Most inverters surge to roughly twice their continuous rating, but check the specification rather than assuming, because an inverter that cannot supply the surge will not start the appliance at all.
Sized on 3.5 peak sun hours, 2 days of autonomy, and LiFePO4 at its recommended depth of discharge. The bank includes a 25% margin for inverter losses, cold weather, and aging.
Every figure above is computed by the same calculators this site publishes, not typed in. To change any assumption, put your own numbers into the appliance power budget and the system sizing calculator.
A tiny house is the situation where off-grid solar makes the most sense and gets designed wrong most often. The loads are modest, the building is efficient, and the whole thing is achievable on a system that fits on the roof. Right up until someone decides to cook with electricity.
The decision that determines everything
Look at what is not on the load list: no oven, no electric kettle, no water heater, no space heater.
That is deliberate, and it is the single decision that makes a tiny house solar system affordable. Everything that makes heat is a resistive load measured in kilowatts rather than watts. An electric kettle draws more power for four minutes than the fridge does in a day.
Doing cooking, hot water, and heating with propane or wood keeps the electrical system small enough to fit on a roof and inside a reasonable budget. Doing them electrically roughly triples the system, and the panels will not fit.
If you take one thing from this page: decide how you cook and heat before you size anything electrical. That decision is worth more than every other efficiency choice combined.
Roof area is the binding constraint
On a cabin or homestead you can put panels on the ground, and the array can be as large as your budget allows. A tiny house on a trailer usually cannot, so the roof sets a hard ceiling.
Depending on layout, a tiny house roof fits somewhere around 800 W to 1.5 kW. That makes this the one situation where panel efficiency genuinely matters, because monocrystalline buys you more watts in the same footprint. Everywhere else on this site the mono-versus-poly question barely matters; here it can be the difference between fitting your system and not.
If the roof cannot hold enough, the honest options are reducing consumption, adding a ground-deployed array when parked, or accepting a generator for the worst weeks.
Why 24 volts
The scenario above uses 24 V, and for a full-time tiny house that is close to non-negotiable.
At 12 V, a 1.5 kW inverter draws around 125 A at full output, which needs heavy and expensive cable and large fuses. The same inverter at 24 V draws about 63 A. The wiring cost difference alone frequently exceeds the price difference in the equipment.
48 V is better again for larger systems, but at this scale 24 V hits the sweet spot for equipment availability and cost.
Two days of autonomy, and why not more
Two days is a reasonable target for a tiny house, and there is a specific reason not to simply buy more.
Batteries are the largest cost in the system and the only component you will replace. On a roof-limited array, a very large bank is also a bank the panels may struggle to refill after a run of bad weather, which is exactly when you need it full. Storage and generation have to be sized together.
If you are somewhere genuinely dark in winter, a small generator is usually cheaper than the extra two days of storage it substitutes for, and it also covers the case where the array is under snow.
Living with it
The fridge is your largest continuous load and the one worth spending money on. A more efficient unit pays for itself in panels and batteries you do not have to buy, and this is the clearest case on the whole site for the principle that reducing consumption beats generating more.
Watch the phantom loads. An inverter left on all day consumes 5 to 30 W doing nothing, which on a 2 kWh budget can be a tenth of everything. Many tiny houses run lighting and water on DC specifically so the inverter can stay off.
Winter is the design case. Size on the sun hours for your worst month. A system built on annual averages will be comfortable in June and short in December, and in a house you live in full time that is not an inconvenience, it is a problem.
Adjusting this for your build
The specification above is computed from the load list rather than typed in, so it will move if your loads differ. Put your own appliances into the appliance power budget and the total into system sizing with the sun hours for your location.
Before buying batteries, read how to size a battery bank, which explains the margins built into the figure above.
Common questions
- How many solar panels does a tiny house need?
- Most full-time tiny houses land between 1 and 2 kW of panel, which is roughly three to five modern residential panels. The figure depends far more on whether you cook and heat with electricity than on the size of the house.
- Can I run everything on electricity in a tiny house?
- You can, but the system roughly triples. Electric cooking, water heating, and space heating are all resistive loads measured in kilowatts, and off-grid they are the most expensive way to do any of those jobs. Propane and wood are what make small systems viable.
- Will the roof hold enough panels?
- That is usually the real constraint. A tiny house roof might fit 800 W to 1.5 kW depending on layout and whether there is a loft. This is the one situation where monocrystalline efficiency genuinely earns its premium, because it buys watts per square foot.
- Do I need 12 V or 24 V?
- 24 V for a full-time tiny house. At 12 V the currents from a 1 kW-plus array need heavy, expensive cable, and inverters above about 2,000 W become impractical. 24 V halves the current for the same power.
- What about running air conditioning?
- A window unit is 500 to 1,500 W continuous, which can double or triple the whole system. A 12 V DC mini-split designed for off-grid use is far more efficient, but it is still the largest load most tiny houses consider.