Sustainable Systems for Tiny Homes: Off-Grid Living

Living Sustainably in Small Spaces

Tiny homes naturally reduce environmental impact through smaller footprints, but you can go further with sustainable systems. This guide covers solar power, water independence, waste management, and eco-friendly living.

Solar Power Systems

Understanding Solar for Tiny Homes

Advantages:

• Energy independence
• Low operating costs after installation
• Environmental benefits
• Quiet (vs. generators)
• Low maintenance

Challenges:

• High upfront cost ($3,000-15,000)
• Weather dependent
• Space for panels
• Technical knowledge needed
• Battery storage expensive

System Sizing

Calculate Your Needs:

1. List All Electrical Loads:

2. Add 20% Safety Margin: 7,220 x 1.2 = 8,664 Wh per day

3. Determine System Size:

Off-Grid System:

• Battery capacity: 2-3 days of use (17,328 - 26,000 Wh)
• Solar panels: Daily use ÷ sun hours (8,664 ÷ 5 = 1,733W)
• Need: ~2,000W solar + 20kWh battery

Grid-Tied with Backup:

• Smaller battery (1 day: 8,664 Wh)
• Fewer panels (1,000-1,500W)
• Lower cost

Solar Components

1. Solar Panels:

Types:

• Monocrystalline: Most efficient (20-22%), expensive, black
• Polycrystalline: Good efficiency (15-17%), affordable, blue
• Thin-film: Flexible, lightweight, lowest efficiency (10-12%)

Sizing:

• Typical panel: 300-400W
• Tiny home needs: 6-12 panels (1,800-4,800W)
• Roof space: 200-300 sq ft for 2,000W

Mounting:

• Roof-mounted (most common)
• Ground-mounted (if land available)
• Portable (for mobile tiny homes)
• Tracking mounts (follow sun, +25% output)

2. Charge Controller:

MPPT (Maximum Power Point Tracking):

• Most efficient (96-99%)
• Best for off-grid
• $200-600
• Worth the investment

PWM (Pulse Width Modulation):

• Less efficient (75-80%)
• Cheaper ($50-150)
• OK for small systems

3. Batteries:

Lithium (LiFePO4):

• Best choice for tiny homes
• 10+ year lifespan
• 80-100% depth of discharge
• Lightweight
• $800-1,200 per kWh

Lead-Acid (AGM):

• Cheaper upfront ($200-400 per kWh)
• Shorter lifespan (3-5 years)
• 50% depth of discharge only
• Heavy
• Require maintenance

Battery Bank Sizing:

• Off-grid: 2-3 days of storage
• Example: 7 kWh/day x 2 days = 14 kWh battery bank
• Lithium: 280Ah @ 48V or 560Ah @ 24V

4. Inverter:

Converts DC (battery) to AC (household power)

Pure Sine Wave:

• Required for sensitive electronics
• More expensive
• Smoother power

Modified Sine Wave:

• Cheaper
• OK for lights, basic appliances
• Can damage some electronics

Sizing:

• Match peak load + 20%
• Example: 2,000W peak load = 2,400W inverter
• Consider surge rating (startup loads)

System Costs

Off-Grid System (2,000W solar, 20kWh battery):

• Solar panels: $3,000-4,000
• Batteries: $10,000-15,000
• Inverter/charger: $1,500-2,500
• Charge controller: $300-600
• Wiring, mounting, misc: $1,000-2,000
• Total: $15,800-24,100

Grid-Tied with Backup (1,500W solar, 10kWh battery):

• Solar panels: $2,250-3,000
• Battery: $5,000-7,500
• Hybrid inverter: $2,000-3,000
• Misc: $750-1,500
• Total: $10,000-15,000

Grid-Tied Only (2,000W solar, no battery):

• Solar panels: $3,000-4,000
• Grid-tie inverter: $800-1,500
• Misc: $500-1,000
• Total: $4,300-6,500

Energy Efficiency Tips

Reduce consumption = smaller/cheaper solar system

Major Savings:

• LED lighting only (75% less than incandescent)
• Energy Star appliances
• Propane for cooking/heat (not electric)
• 12V DC appliances (skip inverter losses)
• Mini-split heat pump (vs. resistance heat)
• Tankless water heater (vs. tank)

Behavioral Changes:

• Use sun hours for heavy loads (washing, etc.)
• Turn off phantom loads
• Dry clothes on line
• Cook outside in summer
• Insulate well (less HVAC needed)

Water Systems

Off-Grid Water Supply

Option 1: Rainwater Collection

System Components:

• Catchment surface (roof)
• Gutters and downspouts
• First-flush diverter (removes debris)
• Storage tank (275-550 gallons)
• Filtration system
• Pressure pump

Calculation:

• Roof area (sq ft) x rainfall (inches) x 0.623 = gallons collected
• Example: 200 sq ft x 30 inches annual rainfall x 0.623 = 3,738 gallons/year

Storage Needed:

• Daily use: 20-50 gallons per person
• Storage: 30-60 days (depends on rainfall frequency)
• Example: 2 people x 30 gal/day x 30 days = 1,800 gallons

Filtration:

• Sediment filter (5 micron)
• Carbon filter (taste, odor, chemicals)
• UV sterilizer (kills bacteria)
• Total cost: $500-1,500

Legality:

• Legal in most states
• Restricted: Colorado (changing), Utah (restricted)
• Check local regulations

Cost:

• Catchment/gutters: $200-500
• Tank: $300-800 (275 gal IBC tote)
• Filtration: $500-1,500
• Pump: $200-400
• Total: $1,200-3,200

Option 2: Well Water

Drilled Well:

• Professional drilling: $5,000-15,000
• Depth: 100-400 ft typical
• Submersible pump: $800-2,000
• Pressure tank: $200-500
• Most reliable long-term

Shallow Well/Point:

• DIY possible
• Under 25 ft depth
• Pitcher pump or shallow well pump
• $500-1,500
• Limited to high water table areas

Option 3: Spring/Creek

Requirements:

• Water rights (legal access)
• Consistent flow
• Uphill from dwelling (gravity feed) or pump
• Filtration essential

Cost:

• Piping: $200-1,000
• Pump (if needed): $200-600
• Filtration: $500-1,500

Option 4: Water Delivery

Hauling Water:

• Fill tanks from municipal source
• 55-gal containers or larger tank
• $0-50 per fill depending on source
• Labor-intensive but cheap startup
• Common for mobile tiny homes

Water Conservation

Low-Flow Fixtures:

• Shower head: 1.5 GPM (vs. 2.5 standard)
• Faucet aerators: 0.5-1.0 GPM
• Toilet: 0.8-1.28 GPF (or composting)
• Savings: 30-50% water use

Greywater System:

• Reuse sink/shower water
• Diverts to irrigation
• Simple system: $200-500
• Complex (filtration): $1,000-3,000
• Check local codes (varies widely)

Navy Showers:

• Wet down (turn off)
• Soap up (water off)
• Rinse off
• Uses 1-3 gallons vs. 10-20

Waste Management

Composting Toilets

How They Work:

• Separate solid/liquid waste
• Solids mixed with carbon (peat, coconut coir)
• Aerobic decomposition
• Results: Compost (safe for non-food plants)

Types:

Self-Contained (All-in-One):

• Nature’s Head: $960
• Air Head: $1,050
• Separett Villa: $1,000
• Compact, no plumbing needed
• Empty every 2-6 weeks (2 people)

Central System:

• Sun-Mar, Phoenix
• $2,000-3,500
• Remote composting chamber
• Less frequent emptying
• More complex install

Advantages:

• No water used
• No septic/sewer needed
• No smell (when used properly)
• Off-grid friendly
• Legal in most areas (check codes)

Disadvantages:

• Upfront cost
• Learning curve
• Must empty manually
• Requires ventilation fan
• Composting material ongoing cost ($50-100/year)

Greywater Management

Sources of Greywater:

• Shower/bath: 25-30 gallons/day
• Bathroom sink: 2-3 gallons/day
• Kitchen sink: 5-10 gallons/day
• Laundry: 15-40 gallons/load

Total: 40-75 gallons/day (2 people)

Disposal Options:

1. Septic System:

• Traditional approach
• $3,000-7,000 installed
• Requires leach field (space needed)
• Permanent foundation usually required

2. Greywater Irrigation:

• Reuse for landscaping
• Branched drain or mulch basin
• No expensive treatment
• Legal in many states (with restrictions)

3. Holding Tank:

• Temporary storage
• Pump out periodically
• Good for mobile tiny homes
• 100-200 gallon tank

4. Treatment System:

• Aerobic treatment unit
• Produces clean water
• Expensive ($2,000-5,000)
• Allows discharge or reuse

Heating and Cooling

Sustainable Heating

1. Mini-Split Heat Pump:

• Most efficient electric option
• Heat + AC in one
• 300% efficiency (SEER 20+)
• $1,000-2,500 installed
• Requires electricity

2. Wood Stove:

• Renewable fuel (if sourced sustainably)
• Off-grid friendly
• $500-2,000 for stove
• Installation: $500-1,500
• Requires clearances (reduces usable space)
• Chimney maintenance

3. Propane Heater:

• Vented wall mount
• Efficient, affordable
• $300-800
• Propane delivery or bottles
• Not fully renewable

4. Radiant Floor:

• Even heat distribution
• Hydronic (water) or electric
• Pairs well with solar thermal
• Installation: $2,000-5,000

Passive Heating/Cooling

Solar Gain:

• South-facing windows (N. hemisphere)
• Thermal mass (concrete, stone, water)
• Overhangs (block summer sun, allow winter)
• Free heat in winter

Ventilation:

• Cross-breeze (windows on opposite sides)
• Skylight venting (hot air rises)
• Ceiling fan (moves air, feels 5°F cooler)

Insulation:

• R-20 walls, R-40 roof minimum
• Eliminates heat loss/gain
• Most cost-effective investment

Shading:

• Awnings, deciduous trees
• Reflective window film
• Light-colored roof
• Reduces cooling needs by 50%

Laundry Solutions

1. Portable Washer:

• Compact, manual or electric
• $100-400
• Uses 5-15 gallons per load
• Drains to sink or outside
• Hand wring or small spin dryer

2. Combo Washer/Dryer:

• All-in-one unit
• 24" wide (compact)
• $1,000-1,500
• Ventless dryer (condenser)
• Uses more water, electricity

3. Laundromat:

• No equipment needed
• No water/energy use at home
• $3-6 per load
• Time investment

4. Hand Washing:

• Cheapest, zero energy
• Time-intensive
• Breathing mobile washer ($50)
• Line dry

Sustainable Materials

Building Materials:

• Reclaimed wood (reduces waste)
• Recycled metal roofing
• Natural insulation (sheep’s wool, cork)
• Low-VOC paints and finishes
• FSC-certified lumber

Furniture:

• Multi-functional pieces
• Second-hand/upcycled
• Locally made
• Durable (avoid disposable)

Waste Reduction

Minimize:

• Buy less, choose quality
• Avoid single-use items
• Digital instead of paper

Reuse:

• Cloth instead of paper products
• Reusable bags, bottles, containers
• Repair instead of replace

Recycle/Compost:

• Food scraps to compost
• Recycle all possible materials
• Proper disposal of hazardous waste

Cost Summary: Full Off-Grid System

Grid-Connected Sustainable:

• Grid-tied solar: $4,300-6,500
• City water (low-flow fixtures): $200-500
• Composting toilet: $960-1,050
• Mini-split heat pump: $1,000-2,500
• Total: $6,460-10,550

Next Steps

• Review Building Guide for integrating systems during construction
• Check Legal Requirements for off-grid regulations
• Explore Living in a Tiny Home for lifestyle adjustments

Sustainable systems align perfectly with tiny home philosophy: independence, simplicity, and minimal environmental impact. Start with the most critical system for your situation and build from there.