Off-grid by project · Tiny homes
Off-grid tiny home solar: panels, batteries, roof space and heat
A tiny home uses far less power than a house, but it also has far less roof. Whether you heat and cook with propane or electricity decides almost everything.
At a glance
Two example tiny homes
These use typical values from the appliance wattage chart, 400 W panels at about 21 sq ft each, and the same sizing math as the off-grid planner.
Propane tiny home: 3.34 kWh a day
Fridge, lights, a 12V water pump, internet, laptop, phones, a ceiling fan and a microwave. Propane covers heat, cooking and hot water.
| Season | 400 W panels | Panel area | Battery (2 days) | Battery (3 days) |
|---|---|---|---|---|
| 5 sun hours (summer) | 3 (1.2 kW) | 63 sq ft | 10.02 kWh | 15.02 kWh |
| 2.5 sun hours (winter) | 6 (2.4 kW) | 126 sq ft | 10.02 kWh | 15.02 kWh |
Inverter: the loads likely to run at the same time total 1,860 W, so plan about 2,325 W continuous and 2,325 W surge. The 12V pump and phone chargers run from the battery, so they don't count toward the inverter.
All-electric tiny home: 10.54 kWh a day
Adds a ductless mini-split for heating and cooling, an induction cooktop, a washer and a TV.
| Season | 400 W panels | Panel area | Battery (2 days) | Battery (3 days) |
|---|---|---|---|---|
| 5 sun hours (summer) | 8 (3.2 kW) | 168 sq ft | 31.63 kWh | 47.43 kWh |
| 2.5 sun hours (winter) | 16 (6.4 kW) | 336 sq ft | 31.63 kWh | 47.43 kWh |
Inverter: the loads likely to run at the same time total 3,160 W, so plan about 3,950 W continuous and 3,950 W surge. The microwave and washer are left out because you can run them when the cooktop is off.
Size your own tiny home system
- Daily use
- 3.34 kWh
- Battery (2 days)
- 10.02 kWh
- Inverter
- 2,325 W
- Startup surge
- 2,325 W
Uses the same math as the off-grid planner at 4 peak sun hours. A planning estimate, not a design.
The calculator's inverter figure assumes every selected appliance runs at once. Size the real inverter from what runs together, as in the examples above.
Will it fit on the roof?
- Measure the usable area, not the whole roof. Vents, skylights, a pitched or curved roof, edge setbacks and tree shade all cut into it. Multiply the panels you need by about 21 sq ft and compare.
- Add a ground mount if it doesn't fit. A ground array can be larger, tilted steeply for winter, and kept clear of snow. It's the usual answer for all-electric tiny homes.
- Check roof structure. Racking adds weight and wind load to a small, light roof. Have the attachment points reviewed, especially on a trailer.
- See how many panels can fit on a roof for a quick area estimate.
How a tiny home system fits together
- Roof or ground arraySized for the darkest month
- Charge controllerOften built into the inverter
- 24V or 48V batteryIndoors, above freezing
- Inverter/chargerSplit-phase for 240V loads
- Panel and outletsWired by an electrician
12V loads like the water pump and USB chargers can run straight from the battery through a fused DC panel. A generator connects to the inverter/charger as a backup input.
Heat, cooking and hot water
- Heat: a ductless mini-split is the most efficient electric option and also cools, but it's still the biggest load in the home. Propane or wood heaters use almost no electricity. Avoid resistance space heaters on solar.
- Cooking: induction is efficient but draws about 1,800 W while it's on, which raises the inverter size. A propane cooktop avoids that.
- Hot water: an electric tank heater isn't practical off-grid. Use a propane tankless heater or a heat-pump water heater.
- 240V appliances: many mini-splits and some cooktops are 240V. You need a split-phase inverter, or choose 120V models. See inverter sizing.
Tiny homes on wheels
- Build for the road. Racking, battery mounts and the inverter must be secured against vibration and wind at highway speed.
- Protect the wiring. Use strain relief and grommets where cables pass through the roof or walls, and fuse every battery connection.
- Keep batteries above freezing. Lithium batteries shouldn't be charged below about 32°F (0°C), so keep them inside the insulated space or use self-heating models. See off-grid solar in winter.
- Plan for a hookup too. An inverter/charger lets you plug into shore power or a generator when you park somewhere with power or the weather turns.
Permits and professional help
Rules for tiny homes vary widely. A tiny home on a foundation is usually treated like a house, with an electrical permit and inspection. One on wheels may fall under RV or park-model standards instead. Either way, the AC wiring and battery installation should be done or reviewed by a licensed electrician. Check with your county before you build. The DIY vs. professional guide breaks down who does what.
FAQ
How many solar panels does an off-grid tiny home need?
A tiny home that uses propane for heat, cooking and hot water needs about 3.34 kWh a day, or 3 × 400 W panels in summer. An all-electric tiny home with a mini-split uses about 10.54 kWh and can need 16 panels in winter.
Will the solar panels fit on my tiny home's roof?
Often not for an all-electric home. Each 400 W panel takes about 21 sq ft, and a tiny home roof loses space to vents, pitch, edges and shade. Many owners add a ground-mount array beside the home.
Can a tiny home run a mini-split on solar?
Yes, but it's the biggest load. A 900 W mini-split running 6 hours a day uses 5.4 kWh, more than everything else in a propane tiny home combined. Many mini-splits are 240V, which needs a split-phase inverter.
What size battery does a tiny home need?
Plan two to three days of storage for cloudy weather. That's about 10–15 kWh for a propane tiny home and 32–47 kWh for an all-electric one, with a generator covering long storms.
Is solar on a tiny home on wheels different?
Yes. Panels, racking and battery mounts must hold up to road vibration and wind at highway speed, and wiring needs strain relief where it crosses between trailer and home. Have the system reviewed before you tow it.