Solar & Off-Grid Power: Energy Independence for Your Tiny Home
Going off-grid is one of the most compelling reasons to build tiny. A small home needs surprisingly little power, making solar a realistic primary energy source.
Sizing Your System
Step 1: Calculate Daily Energy Use
Track everything in watt-hours (Wh) per day:
| Appliance | Watts | Hours/Day | Wh/Day |
|---|---|---|---|
| LED lights (8 bulbs) | 80 | 5 | 400 |
| Refrigerator | 150 | 8 (cycling) | 1,200 |
| Laptop | 60 | 6 | 360 |
| Phone charging | 15 | 3 | 45 |
| Water pump | 60 | 0.5 | 30 |
| Fan/ventilation | 40 | 8 | 320 |
| Misc (router, etc.) | 30 | 24 | 720 |
| Total | 3,075 Wh |
Step 2: Size Your Solar Panels
Rule of thumb: Panels should produce 1.5x your daily consumption to account for cloudy days, winter, and system losses.
- 3,075 Wh × 1.5 = 4,613 Wh needed from panels
- In a location with 5 peak sun hours: 4,613 ÷ 5 = 923 watts of panels
- Round up to 1,000W (about 2-3 panels)
Step 3: Size Your Battery Bank
Store enough for 2 days of autonomy:
- 3,075 Wh × 2 days = 6,150 Wh of storage
- With lithium batteries (80% depth of discharge): 6,150 ÷ 0.8 = 7,688 Wh
- A 48V, 200Ah lithium battery bank provides approximately 9,600 Wh
Step 4: Choose an Inverter
- Pure sine wave (mandatory for modern electronics)
- Size for your peak load plus 20% headroom
- Common choice: 3,000W inverter/charger for a tiny home
Installation
Panel Mounting
For tiny homes on trailers, you have options:
- Roof-mounted: Tilting frame that adjusts seasonally. Clean look but adds weight and height.
- Ground-mounted: Deployed when parked. Optimal angle, easy to clean, but requires setup time.
- Portable panels: Fold up for travel. Least power, most flexibility.
Wiring Best Practices
- Use appropriately sized wire — voltage drop matters more in 12V/24V systems
- Install a combiner box if running multiple panel strings
- Keep wire runs as short as possible
- Use MC4 connectors for panel connections
- Install a disconnect between panels and charge controller
Charge Controller
- MPPT (Maximum Power Point Tracking): 15-20% more efficient than PWM. Worth the cost.
- Size for your panel array's maximum voltage and current
- Mount in a ventilated area — they generate heat
System Components Diagram
Solar Panels → Combiner Box → Charge Controller → Battery Bank
↓
Loads ← Breaker Panel ← Inverter/Charger ← Battery Bank
↑
Shore Power (backup)
Maintenance
Solar systems are low-maintenance but not zero-maintenance:
- Monthly: Check battery state of charge and voltage
- Quarterly: Clean panels, check connections for corrosion
- Annually: Inspect wiring, test breakers, check battery health
- As needed: Clear snow from panels, trim shade-casting branches
Costs
A complete off-grid solar system for a tiny home:
| Component | Cost |
|---|---|
| Solar panels (1,000W) | $800-$1,200 |
| Lithium battery bank | $2,000-$4,000 |
| MPPT charge controller | $200-$500 |
| Inverter/charger | $800-$1,500 |
| Wiring, breakers, misc | $300-$600 |
| Total | $4,100-$7,800 |
The payback period depends on your local electricity cost, but most systems pay for themselves within 5-8 years — and you get energy independence as a bonus.