How to Wire a 200 Amp Electrical Service for an Off-Grid Tiny House

Moving into a tiny house off the grid comes with unique electrical wiring considerations. As you downsize your living space, you'll need to right-size your electrical system as well. Wiring a 200 amp service provides ample power for most tiny houses, while keeping electrical costs reasonable. Follow this guide to learn how to wire a 200 amp service for your off-grid tiny home.

Choosing the Right Size Service

When wiring an off-grid home, the size of your electrical service largely depends on your expected electrical usage.

• For a smaller tiny house under 400 square feet, a 100 amp panel may suffice. This allows for basic lighting, appliances like a refrigerator and microwave, and some low-power electronics.

• Most typical tiny homes between 400-800 square feet will do fine with a 200 amp service. This covers lighting, major appliances, HVAC systems, and moderate electronic usage.

• Larger tiny houses over 800 square feet may need a 400 amp service for more high-power appliances and electronics.

Consider an electrical load calculation to estimate your required amperage. Factor in all lighting, appliance usage, electronics charging, HVAC, and any high-power specialty equipment. Leave room for future expansion too.

Sourcing a 200 Amp Off-Grid Panel

Look for a 200 amp load center or panelboard designed specifically for off-grid applications. Common brands include Square D, Eaton, Siemens, and GE.

Key features to look for include:

• Off-grid capable without transfer switch
• 30-42 circuits to cover your electrical needs
• Surge protection for electronics
• Solar ready for connecting renewable energy

Prices range from $300-800 depending on brand and features. Budget more for the enclosure, breakers, and other wiring accessories.

Solar Sizing to Support 200 Amps

To power a 200 amp panel off-grid, your solar array needs to provide at least 4,000-5,000 watts of solar capacity. This factors in inverter efficiency losses of 20-30%.

For example:

• 5,000 watts / 12 volts = 417 amps at peak solar input
• 417 amps x 0.8 inverter efficiency = 334 amps usable capacity

To generate this much solar power, you'll need around 20-25 x 250 watt solar panels, depending on panel wattage and sun exposure. Connect panels in series for a 48 volt nominal array voltage.

Work with a solar integrator to properly size your solar array, inverter, and battery bank. Oversizing your solar capacity provides a safety margin for increased electrical usage down the road.

Wiring the 200 Amp Panel

Follow standard wiring codes and procedures for installing a 200 amp load center:

• Mount the interior panelboard on plywood backing with adequate clearance.

• Run 2/0 or 4/0 AWG copper feeder wires from the charge controller or inverters to the main panel lugs. Keep wire runs as short as possible.

• Use a main breaker matched to your service size, such as a 200 amp main breaker. This serves as the overall disconnect switch.

• Install individual branch circuit breakers for each circuit in the panel. Label all circuits clearly.

• Follow code for using GFCI and AFCI breakers where required in kitchens, bathrooms, and living areas.

• Use thick 6 AWG copper wire for high-draw appliance circuits like ranges or electric water heaters.

• Verify the neutral and ground buses are properly isolated with no bonding wire. Ground to your system earth or home frame.

• Consider installing a whole house surge arrestor to protect electronics.

Always have an electrician inspect your panel wiring for safety and code compliance.

Considering Backup Power Sources

Even robust solar systems benefit from an energy storage or backup power source. Options to prevent power outages include:

• Sufficient battery bank capacity, at least 5-10kWh for 200 amps.
• Propane generator wired into a subpanel via transfer switch.
• Gasoline generator for temporary backup power only.
• Small battery backups just for essential circuits.

Prioritize critical loads like lighting, refrigeration, and healthcare devices when designing your backup system.

While wiring an off-grid electrical system takes careful planning, the freedom and sustainability benefits make it worthwhile. Sizing your system right and following electrical codes ensures reliable power for your unique tiny house needs.